1/30/20 Pilot/Controller Glossary PILOT/CONTROLLER GLOSSARY · 2020-01-30 · 1/30/20 Pilot/Controller Glossary PCG−1 PILOT/CONTROLLER GLOSSARY PURPOSE a. This Glossary was compiled

Pilot/Controller Glossary1/30/20

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PILOT/CONTROLLERGLOSSARY

PURPOSE

a. This Glossary was compiled to promote a common understanding of the terms used in the Air TrafficControl system. It includes those terms which are intended for pilot/controller communications. Those termsmost frequently used in pilot/controller communications are printed in bold italics. The definitions are primarilydefined in an operational sense applicable to both users and operators of the National Airspace System. Use ofthe Glossary will preclude any misunderstandings concerning the system’s design, function, and purpose.

b. Because of the international nature of flying, terms used in the Lexicon, published by the InternationalCivil Aviation Organization (ICAO), are included when they differ from FAA definitions. These terms arefollowed by “[ICAO].” For the reader’s convenience, there are also cross references to related terms in other partsof the Glossary and to other documents, such as the Code of Federal Regulations (CFR) and the AeronauticalInformation Manual (AIM).

c. This Glossary will be revised, as necessary, to maintain a common understanding of the system.

EXPLANATION OF CHANGES

d. Terms Added:AIRCRAFT HAZARD AREA (AHA)AUTOMATIC DEPENDENT SURVEILLANCE−BROADCAST IN (ADS−B In)AUTOMATIC DEPENDENT SURVEILLANCE−BROADCAST OUT (ADS−B Out)CONTINGENCY HAZARD AREA (CHA)COOPERATIVE SURVEILLANCENON−COOPERATIVE SURVEILLANCEPRM APPROACHREFINED HAZARD AREA (RHA)ROUND−ROBIN FLIGHT PLANSPACE−BASED ADS−B (SBA)SPOOFINGTRANSITIONAL HAZARD AREA (THA)UNSERVICEABLE (U/S)

e. Terms Deleted:GROUND−BASED TRANSCEIVER (GBT)HAZARDOUS INFLIGHT WEATHER ADVISORY SERVICE (HIWAS)HIWAS BROADCAST AREAHIWAS OUTLET AREAILS PRM APPROACHRUNWAY VISIBILITY VALUE (RVV)

f. Terms Modified:AREA NAVIGATION (RNAV) GLOBAL POSITIONING SYSTEM (GPS) PRECISION RUNWAY

MONITORING (PRM) APPROACHAUTOMATIC DEPENDENT SURVEILLANCE−BROADCAST (ADS−B)FUSION [STARS/CARTS]GLOBAL NAVIGATION SATELLITE SYSTEM (GNSS) [ICAO]

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ICINGJAMMINGOUT OF SERVICERADARSQUAWK (Mode, Code, Function)STOP ALTITUDE SQUAWKSTOP SQUAWK (Mode or Code)TARGETTARGET SYMBOLTRANSMISSOMETERVISIBILITY

g. Editorial/format changes were made where necessary. Revision bars were not used due to the insignificantnature of the changes.


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AAAI−

(See ARRIVAL AIRCRAFT INTERVAL.)

AAR−(See AIRPORT ARRIVAL RATE.)

ABBREVIATED IFR FLIGHT PLANS− Anauthorization by ATC requiring pilots to submit onlythat information needed for the purpose of ATC. Itincludes only a small portion of the usual IFR flightplan information. In certain instances, this may beonly aircraft identification, location, and pilotrequest. Other information may be requested ifneeded by ATC for separation/control purposes. It isfrequently used by aircraft which are airborne anddesire an instrument approach or by aircraft which areon the ground and desire a climb to VFR-on-top.

(See VFR-ON-TOP.)(Refer to AIM.)

ABEAM− An aircraft is “abeam” a fix, point, orobject when that fix, point, or object is approximately90 degrees to the right or left of the aircraft track.Abeam indicates a general position rather than aprecise point.

ABORT− To terminate a preplanned aircraftmaneuver; e.g., an aborted takeoff.

ACC [ICAO]−(See ICAO term AREA CONTROL CENTER.)

ACCELERATE-STOP DISTANCE AVAILABLE−The runway plus stopway length declared availableand suitable for the acceleration and deceleration ofan airplane aborting a takeoff.

ACCELERATE-STOP DISTANCE AVAILABLE[ICAO]− The length of the take-off run available plusthe length of the stopway if provided.

ACDO−(See AIR CARRIER DISTRICT OFFICE.)

ACKNOWLEDGE− Let me know that you havereceived and understood this message.

ACL−(See AIRCRAFT LIST.)

ACLS−(See AUTOMATIC CARRIER LANDINGSYSTEM.)

ACLT−(See ACTUAL CALCULATED LANDING TIME.)

ACROBATIC FLIGHT− An intentional maneuverinvolving an abrupt change in an aircraft’s attitude, anabnormal attitude, or abnormal acceleration notnecessary for normal flight.

(See ICAO term ACROBATIC FLIGHT.)(Refer to 14 CFR Part 91.)

ACROBATIC FLIGHT [ICAO]− Maneuvers inten-tionally performed by an aircraft involving an abruptchange in its attitude, an abnormal attitude, or anabnormal variation in speed.

ACTIVE RUNWAY−(See RUNWAY IN USE/ACTIVE RUNWAY/DUTYRUNWAY.)

ACTUAL CALCULATED LANDING TIME−ACLT is a flight’s frozen calculated landing time. Anactual time determined at freeze calculated landingtime (FCLT) or meter list display interval (MLDI) forthe adapted vertex for each arrival aircraft based uponrunway configuration, airport acceptance rate, airportarrival delay period, and other metered arrivalaircraft. This time is either the vertex time of arrival(VTA) of the aircraft or the tentative calculatedlanding time (TCLT)/ACLT of the previous aircraftplus the arrival aircraft interval (AAI), whichever islater. This time will not be updated in response to theaircraft’s progress.

ACTUAL NAVIGATION PERFORMANCE(ANP)−

(See REQUIRED NAVIGATIONPERFORMANCE.)

ADDITIONAL SERVICES− Advisory informationprovided by ATC which includes but is not limited tothe following:

a. Traffic advisories.

b. Vectors, when requested by the pilot, to assistaircraft receiving traffic advisories to avoid observedtraffic.

c. Altitude deviation information of 300 feet ormore from an assigned altitude as observed on averified (reading correctly) automatic altitudereadout (Mode C).

d. Advisories that traffic is no longer a factor.


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e. Weather and chaff information.

f. Weather assistance.

g. Bird activity information.

h. Holding pattern surveillance. Additional ser-vices are provided to the extent possible contingentonly upon the controller’s capability to fit them intothe performance of higher priority duties and on thebasis of limitations of the radar, volume of traffic,frequency congestion, and controller workload. Thecontroller has complete discretion for determining ifhe/she is able to provide or continue to provide aservice in a particular case. The controller’s reasonnot to provide or continue to provide a service in aparticular case is not subject to question by the pilotand need not be made known to him/her.

(See TRAFFIC ADVISORIES.)(Refer to AIM.)

ADF−(See AUTOMATIC DIRECTION FINDER.)

ADIZ−(See AIR DEFENSE IDENTIFICATION ZONE.)

ADLY−(See ARRIVAL DELAY.)

ADMINISTRATOR− The Federal Aviation Admin-istrator or any person to whom he/she has delegatedhis/her authority in the matter concerned.

ADR−(See AIRPORT DEPARTURE RATE.)

ADS [ICAO]−(See ICAO term AUTOMATIC DEPENDENTSURVEILLANCE.)

ADS−B−(See AUTOMATIC DEPENDENTSURVEILLANCE−BROADCAST.)

ADS−C−(See AUTOMATIC DEPENDENTSURVEILLANCE−CONTRACT.)

ADVISE INTENTIONS− Tell me what you plan todo.

ADVISORY− Advice and information provided toassist pilots in the safe conduct of flight and aircraftmovement.

(See ADVISORY SERVICE.)

ADVISORY FREQUENCY− The appropriate fre-quency to be used for Airport Advisory Service.

(See LOCAL AIRPORT ADVISORY.)(See UNICOM.)(Refer to ADVISORY CIRCULAR NO. 90-42.)(Refer to AIM.)

ADVISORY SERVICE− Advice and informationprovided by a facility to assist pilots in the safeconduct of flight and aircraft movement.

(See ADDITIONAL SERVICES.)(See LOCAL AIRPORT ADVISORY.)(See RADAR ADVISORY.)(See SAFETY ALERT.)(See TRAFFIC ADVISORIES.)(Refer to AIM.)

AERIAL REFUELING− A procedure used by themilitary to transfer fuel from one aircraft to anotherduring flight.

(Refer to VFR/IFR Wall Planning Charts.)

AERODROME− A defined area on land or water(including any buildings, installations and equip-ment) intended to be used either wholly or in part forthe arrival, departure, and movement of aircraft.

AERODROME BEACON [ICAO]− Aeronauticalbeacon used to indicate the location of an aerodromefrom the air.

AERODROME CONTROL SERVICE [ICAO]− Airtraffic control service for aerodrome traffic.

AERODROME CONTROL TOWER [ICAO]− Aunit established to provide air traffic control serviceto aerodrome traffic.

AERODROME ELEVATION [ICAO]− The eleva-tion of the highest point of the landing area.

AERODROME TRAFFIC CIRCUIT [ICAO]− Thespecified path to be flown by aircraft operating in thevicinity of an aerodrome.

AERONAUTICAL BEACON− A visual NAVAIDdisplaying flashes of white and/or colored light toindicate the location of an airport, a heliport, alandmark, a certain point of a Federal airway inmountainous terrain, or an obstruction.

(See AIRPORT ROTATING BEACON.)(Refer to AIM.)

AERONAUTICAL CHART− A map used in airnavigation containing all or part of the following:topographic features, hazards and obstructions,


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navigation aids, navigation routes, designatedairspace, and airports. Commonly used aeronauticalcharts are:

a. Sectional Aeronautical Charts (1:500,000)−Designed for visual navigation of slow or mediumspeed aircraft. Topographic information on thesecharts features the portrayal of relief and a judiciousselection of visual check points for VFR flight.Aeronautical information includes visual and radioaids to navigation, airports, controlled airspace,permanent special use airspace (SUA), obstructions,and related data.

b. VFR Terminal Area Charts (1:250,000)−Depict Class B airspace which provides for thecontrol or segregation of all the aircraft within ClassB airspace. The chart depicts topographic informa-tion and aeronautical information which includesvisual and radio aids to navigation, airports,controlled airspace, permanent SUA, obstructions,and related data.

c. En Route Low Altitude Charts− Provideaeronautical information for en route instrumentnavigation (IFR) in the low altitude stratum.Information includes the portrayal of airways, limitsof controlled airspace, position identification andfrequencies of radio aids, selected airports, minimumen route and minimum obstruction clearancealtitudes, airway distances, reporting points, perma-nent SUA, and related data. Area charts, which are apart of this series, furnish terminal data at a largerscale in congested areas.

d. En Route High Altitude Charts− Provideaeronautical information for en route instrumentnavigation (IFR) in the high altitude stratum.Information includes the portrayal of jet routes,identification and frequencies of radio aids, selectedairports, distances, time zones, special use airspace,and related information.

e. Instrument Approach Procedure (IAP) Charts−Portray the aeronautical data which is required toexecute an instrument approach to an airport. Thesecharts depict the procedures, including all relateddata, and the airport diagram. Each procedure isdesignated for use with a specific type of electronicnavigation system including NDB, TACAN, VOR,ILS RNAV and GLS. These charts are identified bythe type of navigational aid(s)/equipment required toprovide final approach guidance.

f. Instrument Departure Procedure (DP) Charts−Designed to expedite clearance delivery and tofacilitate transition between takeoff and en routeoperations. Each DP is presented as a separate chartand may serve a single airport or more than oneairport in a given geographical location.

g. Standard Terminal Arrival (STAR) Charts−Designed to expedite air traffic control arrivalprocedures and to facilitate transition between enroute and instrument approach operations. EachSTAR procedure is presented as a separate chart andmay serve a single airport or more than one airport ina given geographical location.

h. Airport Taxi Charts− Designed to expedite theefficient and safe flow of ground traffic at an airport.These charts are identified by the official airportname; e.g., Ronald Reagan Washington NationalAirport.

(See ICAO term AERONAUTICAL CHART.)

AERONAUTICAL CHART [ICAO]− A representa-tion of a portion of the earth, its culture and relief,specifically designated to meet the requirements ofair navigation.

AERONAUTICAL INFORMATION MANUAL(AIM)− A primary FAA publication whose purposeis to instruct airmen about operating in the NationalAirspace System of the U.S. It provides basic flightinformation, ATC Procedures and general instruc-tional information concerning health, medical facts,factors affecting flight safety, accident and hazardreporting, and types of aeronautical charts and theiruse.

AERONAUTICAL INFORMATION PUBLICA-TION (AIP) [ICAO]− A publication issued by or withthe authority of a State and containing aeronauticalinformation of a lasting character essential to airnavigation.

(See CHART SUPPLEMENT U.S.)

AFFIRMATIVE− Yes.

AFIS−(See AUTOMATIC FLIGHT INFORMATIONSERVICE − ALASKA FSSs ONLY.)

AFP−(See AIRSPACE FLOW PROGRAM.)

AHA−(See AIRCRAFT HAZARD AREA.)

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AIM−(See AERONAUTICAL INFORMATIONMANUAL.)

AIP [ICAO]−(See ICAO term AERONAUTICALINFORMATION PUBLICATION.)

AIR CARRIER DISTRICT OFFICE− An FAA fieldoffice serving an assigned geographical area, staffedwith Flight Standards personnel serving the aviationindustry and the general public on matters related tothe certification and operation of scheduled aircarriers and other large aircraft operations.

AIR DEFENSE EMERGENCY− A military emer-gency condition declared by a designated authority.This condition exists when an attack upon thecontinental U.S., Alaska, Canada, or U.S. installa-tions in Greenland by hostile aircraft or missiles isconsidered probable, is imminent, or is taking place.

(Refer to AIM.)

AIR DEFENSE IDENTIFICATION ZONE (ADIZ)−An area of airspace over land or water in which theready identification, location, and control of allaircraft (except for Department of Defense and lawenforcement aircraft) is required in the interest ofnational security.

Note: ADIZ locations and operating and flight planrequirements for civil aircraft operations arespecified in 14 CFR Part 99.

(Refer to AIM.)

AIR NAVIGATION FACILITY− Any facility usedin, available for use in, or designed for use in, aid ofair navigation, including landing areas, lights, anyapparatus or equipment for disseminating weatherinformation, for signaling, for radio-directionalfinding, or for radio or other electrical communica-tion, and any other structure or mechanism having asimilar purpose for guiding or controlling flight in theair or the landing and takeoff of aircraft.

(See NAVIGATIONAL AID.)

AIR ROUTE SURVEILLANCE RADAR− Air routetraffic control center (ARTCC) radar used primarilyto detect and display an aircraft’s position while enroute between terminal areas. The ARSR enablescontrollers to provide radar air traffic control servicewhen aircraft are within the ARSR coverage. In someinstances, ARSR may enable an ARTCC to provideterminal radar services similar to but usually more

limited than those provided by a radar approachcontrol.

AIR ROUTE TRAFFIC CONTROL CENTER(ARTCC)− A facility established to provide air trafficcontrol service to aircraft operating on IFR flightplans within controlled airspace and principallyduring the en route phase of flight. When equipmentcapabilities and controller workload permit, certainadvisory/assistance services may be provided to VFRaircraft.

(See EN ROUTE AIR TRAFFIC CONTROLSERVICES.)

(Refer to AIM.)

AIR TAXI− Used to describe a helicopter/VTOLaircraft movement conducted above the surface butnormally not above 100 feet AGL. The aircraft mayproceed either via hover taxi or flight at speeds morethan 20 knots. The pilot is solely responsible forselecting a safe airspeed/altitude for the operationbeing conducted.

(See HOVER TAXI.)(Refer to AIM.)

AIR TRAFFIC− Aircraft operating in the air or on anairport surface, exclusive of loading ramps andparking areas.

(See ICAO term AIR TRAFFIC.)

AIR TRAFFIC [ICAO]− All aircraft in flight oroperating on the maneuvering area of an aerodrome.

AIR TRAFFIC CLEARANCE− An authorization byair traffic control for the purpose of preventingcollision between known aircraft, for an aircraft toproceed under specified traffic conditions withincontrolled airspace. The pilot-in-command of anaircraft may not deviate from the provisions of avisual flight rules (VFR) or instrument flight rules(IFR) air traffic clearance except in an emergency orunless an amended clearance has been obtained.Additionally, the pilot may request a differentclearance from that which has been issued by airtraffic control (ATC) if information available to thepilot makes another course of action more practicableor if aircraft equipment limitations or companyprocedures forbid compliance with the clearanceissued. Pilots may also request clarification oramendment, as appropriate, any time a clearance isnot fully understood, or considered unacceptablebecause of safety of flight. Controllers should, insuch instances and to the extent of operationalpracticality and safety, honor the pilot’s request.



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14 CFR Part 91.3(a) states: “The pilot in commandof an aircraft is directly responsible for, and is thefinal authority as to, the operation of that aircraft.”THE PILOT IS RESPONSIBLE TO REQUEST ANAMENDED CLEARANCE if ATC issues aclearance that would cause a pilot to deviate from arule or regulation, or in the pilot’s opinion, wouldplace the aircraft in jeopardy.

(See ATC INSTRUCTIONS.)(See ICAO term AIR TRAFFIC CONTROLCLEARANCE.)

AIR TRAFFIC CONTROL− A service operated byappropriate authority to promote the safe, orderly andexpeditious flow of air traffic.

(See ICAO term AIR TRAFFIC CONTROLSERVICE.)

AIR TRAFFIC CONTROL CLEARANCE [ICAO]−Authorization for an aircraft to proceed underconditions specified by an air traffic control unit.

Note 1: For convenience, the term air traffic controlclearance is frequently abbreviated to clearancewhen used in appropriate contexts.

Note 2: The abbreviated term clearance may beprefixed by the words taxi, takeoff, departure, enroute, approach or landing to indicate the particularportion of flight to which the air traffic control clear-ance relates.

AIR TRAFFIC CONTROL SERVICE−(See AIR TRAFFIC CONTROL.)

AIR TRAFFIC CONTROL SERVICE [ICAO]− Aservice provided for the purpose of:

a. Preventing collisions:

1. Between aircraft; and

2. On the maneuvering area between aircraftand obstructions.

b. Expediting and maintaining an orderly flow ofair traffic.

AIR TRAFFIC CONTROL SPECIALIST− A personauthorized to provide air traffic control service.

(See AIR TRAFFIC CONTROL.)(See FLIGHT SERVICE STATION.)(See ICAO term CONTROLLER.)

AIR TRAFFIC CONTROL SYSTEM COMMANDCENTER (ATCSCC)− An Air Traffic TacticalOperations facility responsible for monitoring andmanaging the flow of air traffic throughout the NAS,producing a safe, orderly, and expeditious flow of

traffic while minimizing delays. The followingfunctions are located at the ATCSCC:

a. Central Altitude Reservation Function(CARF). Responsible for coordinating, planning,and approving special user requirements under theAltitude Reservation (ALTRV) concept.

(See ALTITUDE RESERVATION.)

b. Airport Reservation Office (ARO). Monitorsthe operation and allocation of reservations forunscheduled operations at airports designated by theAdministrator as High Density Airports. Theseairports are generally known as slot controlledairports. The ARO allocates reservations on a firstcome, first served basis determined by the time therequest is received at the ARO.

(Refer to 14 CFR Part 93.)(See CHART SUPPLEMENT U.S.)

c. U.S. Notice to Airmen (NOTAM) Office.Responsible for collecting, maintaining, and distrib-uting NOTAMs for the U.S. civilian and military, aswell as international aviation communities.

(See NOTICE TO AIRMEN.)

d. Weather Unit. Monitor all aspects of weatherfor the U.S. that might affect aviation including cloudcover, visibility, winds, precipitation, thunderstorms,icing, turbulence, and more. Provide forecasts basedon observations and on discussions with meteorolo-gists from various National Weather Service offices,FAA facilities, airlines, and private weather services.

AIR TRAFFIC SERVICE− A generic term meaning:

a. Flight Information Service.

b. Alerting Service.

c. Air Traffic Advisory Service.

d. Air Traffic Control Service:

1. Area Control Service,

2. Approach Control Service, or

3. Airport Control Service.

AIR TRAFFIC SERVICE (ATS) ROUTES − Theterm “ATS Route” is a generic term that includes“VOR Federal airways,” “colored Federal airways,”“jet routes,” and “RNAV routes.” The term “ATSroute” does not replace these more familiar routenames, but serves only as an overall title when listingthe types of routes that comprise the United Statesroute structure.

AIRBORNE− An aircraft is considered airbornewhen all parts of the aircraft are off the ground.



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AIRBORNE DELAY− Amount of delay to beencountered in airborne holding.

AIRCRAFT− Device(s) that are used or intended tobe used for flight in the air, and when used in air trafficcontrol terminology, may include the flight crew.

(See ICAO term AIRCRAFT.)

AIRCRAFT [ICAO]− Any machine that can derivesupport in the atmosphere from the reactions of the airother than the reactions of the air against the earth’ssurface.

AIRCRAFT APPROACH CATEGORY− Agrouping of aircraft based on a speed of 1.3 times thestall speed in the landing configuration at maximumgross landing weight. An aircraft must fit in only onecategory. If it is necessary to maneuver at speeds inexcess of the upper limit of a speed range for acategory, the minimums for the category for thatspeed must be used. For example, an aircraft whichfalls in Category A, but is circling to land at a speedin excess of 91 knots, must use the approachCategory B minimums when circling to land. Thecategories are as follows:

a. Category A− Speed less than 91 knots.

b. Category B− Speed 91 knots or more but lessthan 121 knots.

c. Category C− Speed 121 knots or more but lessthan 141 knots.

d. Category D− Speed 141 knots or more but lessthan 166 knots.

e. Category E− Speed 166 knots or more.(Refer to 14 CFR Part 97.)

AIRCRAFT CLASSES− For the purposes of WakeTurbulence Separation Minima, ATC classifiesaircraft as Super, Heavy, Large, and Small as follows:

a. Super. The Airbus A-380-800 (A388) and theAntonov An-225 (A225) are classified as super.

b. Heavy− Aircraft capable of takeoff weights of300,000 pounds or more whether or not they areoperating at this weight during a particular phase offlight.

c. Large− Aircraft of more than 41,000 pounds,maximum certificated takeoff weight, up to but notincluding 300,000 pounds.

d. Small− Aircraft of 41,000 pounds or lessmaximum certificated takeoff weight.

(Refer to AIM.)

AIRCRAFT CONFLICT− Predicted conflict, withinEDST of two aircraft, or between aircraft andairspace. A Red alert is used for conflicts when thepredicted minimum separation is 5 nautical miles orless. A Yellow alert is used when the predictedminimum separation is between 5 and approximately12 nautical miles. A Blue alert is used for conflictsbetween an aircraft and predefined airspace.

(See EN ROUTE DECISION SUPPORTTOOL.)

AIRCRAFT LIST (ACL)− A view available withEDST that lists aircraft currently in or predicted to bein a particular sector’s airspace. The view containstextual flight data information in line format and maybe sorted into various orders based on the specificneeds of the sector team.

(See EN ROUTE DECISION SUPPORTTOOL.)

AIRCRAFT SURGE LAUNCH ANDRECOVERY− Procedures used at USAF bases toprovide increased launch and recovery rates ininstrument flight rules conditions. ASLAR is basedon:

a. Reduced separation between aircraft which isbased on time or distance. Standard arrival separationapplies between participants including multipleflights until the DRAG point. The DRAG point is apublished location on an ASLAR approach whereaircraft landing second in a formation slows to apredetermined airspeed. The DRAG point is thereference point at which MARSA applies asexpanding elements effect separation within a flightor between subsequent participating flights.

b. ASLAR procedures shall be covered in a Letterof Agreement between the responsible USAFmilitary ATC facility and the concerned FederalAviation Administration facility. Initial ApproachFix spacing requirements are normally addressed asa minimum.

AIRCRAFT HAZARD AREA (AHA)− Used byATC to segregate air traffic from a launch vehicle,reentry vehicle, amateur rocket, jettisoned stages,hardware, or falling debris generated by failuresassociated with any of these activities. An AHA is



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designated via NOTAM as either a TFR or stationaryALTRV. Unless otherwise specified, the verticallimits of an AHA are from the surface to unlimited.

(See CONTINGENCY HAZARD AREA.)(See REFINED HAZARD AREA.)(See TRANSITIONAL HAZARD AREA.)

AIRCRAFT WAKE TURBULENCE CATE-GORIES− For the purpose of Wake TurbulenceRecategorization (RECAT) Separation Minima, ATCgroups aircraft into categories ranging from CategoryA through Category I, dependent upon the version ofRECAT that is applied. Specific category assign-ments vary and are listed in the RECAT Orders.

AIRMEN’S METEOROLOGICAL INFORMA-TION (AIRMET)− In-flight weather advisoriesissued only to amend the Aviation Surface Forecast,Aviation Cloud Forecast, or area forecast concerningweather phenomena which are of operational interestto all aircraft and potentially hazardous to aircrafthaving limited capability because of lack ofequipment, instrumentation, or pilot qualifications.AIRMETs concern weather of less severity than thatcovered by SIGMETs or Convective SIGMETs.AIRMETs cover moderate icing, moderate turbu-lence, sustained winds of 30 knots or more at thesurface, widespread areas of ceilings less than 1,000feet and/or visibility less than 3 miles, and extensivemountain obscurement.

(See AWW.)(See CONVECTIVE SIGMET.)(See CWA.)(See SIGMET.)(Refer to AIM.)

AIRPORT− An area on land or water that is used orintended to be used for the landing and takeoff ofaircraft and includes its buildings and facilities, ifany.

AIRPORT ADVISORY AREA− The area within tenmiles of an airport without a control tower or wherethe tower is not in operation, and on which a FlightService Station is located.

(See LOCAL AIRPORT ADVISORY.)(Refer to AIM.)

AIRPORT ARRIVAL RATE (AAR)− A dynamicinput parameter specifying the number of arrivingaircraft which an airport or airspace can accept fromthe ARTCC per hour. The AAR is used to calculate

the desired interval between successive arrivalaircraft.

AIRPORT DEPARTURE RATE (ADR)− A dynamicparameter specifying the number of aircraft whichcan depart an airport and the airspace can accept perhour.

AIRPORT ELEVATION− The highest point of anairport’s usable runways measured in feet from meansea level.

(See TOUCHDOWN ZONE ELEVATION.)(See ICAO term AERODROME ELEVATION.)

AIRPORT LIGHTING− Various lighting aids thatmay be installed on an airport. Types of airportlighting include:

a. Approach Light System (ALS)− An airportlighting facility which provides visual guidance tolanding aircraft by radiating light beams in adirectional pattern by which the pilot aligns theaircraft with the extended centerline of the runway onhis/her final approach for landing. Condenser-Discharge Sequential Flashing Lights/SequencedFlashing Lights may be installed in conjunction withthe ALS at some airports. Types of Approach LightSystems are:

1. ALSF-1− Approach Light System withSequenced Flashing Lights in ILS Cat-I configura-tion.

2. ALSF-2− Approach Light System withSequenced Flashing Lights in ILS Cat-II configura-tion. The ALSF-2 may operate as an SSALR whenweather conditions permit.

3. SSALF− Simplified Short Approach LightSystem with Sequenced Flashing Lights.

4. SSALR− Simplified Short Approach LightSystem with Runway Alignment Indicator Lights.

5. MALSF− Medium Intensity Approach LightSystem with Sequenced Flashing Lights.

6. MALSR− Medium Intensity Approach LightSystem with Runway Alignment Indicator Lights.

7. RLLS− Runway Lead-in Light SystemConsists of one or more series of flashing lightsinstalled at or near ground level that provides positivevisual guidance along an approach path, eithercurving or straight, where special problems exist withhazardous terrain, obstructions, or noise abatementprocedures.

8. RAIL− Runway Alignment Indicator Lights−Sequenced Flashing Lights which are installed onlyin combination with other light systems.



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9. ODALS− Omnidirectional Approach Light-ing System consists of seven omnidirectionalflashing lights located in the approach area of anonprecision runway. Five lights are located on therunway centerline extended with the first lightlocated 300 feet from the threshold and extending atequal intervals up to 1,500 feet from the threshold.The other two lights are located, one on each side ofthe runway threshold, at a lateral distance of 40 feetfrom the runway edge, or 75 feet from the runwayedge when installed on a runway equipped with aVASI.

(Refer to FAA Order JO 6850.2, VISUALGUIDANCE LIGHTING SYSTEMS.)

b. Runway Lights/Runway Edge Lights− Lightshaving a prescribed angle of emission used to definethe lateral limits of a runway. Runway lights areuniformly spaced at intervals of approximately 200feet, and the intensity may be controlled or preset.

c. Touchdown Zone Lighting− Two rows oftransverse light bars located symmetrically about therunway centerline normally at 100 foot intervals. Thebasic system extends 3,000 feet along the runway.

d. Runway Centerline Lighting− Flush centerlinelights spaced at 50-foot intervals beginning 75 feetfrom the landing threshold and extending to within 75feet of the opposite end of the runway.

e. Threshold Lights− Fixed green lights arrangedsymmetrically left and right of the runway centerline,identifying the runway threshold.

f. Runway End Identifier Lights (REIL)− Twosynchronized flashing lights, one on each side of therunway threshold, which provide rapid and positiveidentification of the approach end of a particularrunway.

g. Visual Approach Slope Indicator (VASI)− Anairport lighting facility providing vertical visualapproach slope guidance to aircraft during approachto landing by radiating a directional pattern of highintensity red and white focused light beams whichindicate to the pilot that he/she is “on path” if he/shesees red/white, “above path” if white/white, and“below path” if red/red. Some airports serving largeaircraft have three-bar VASIs which provide twovisual glide paths to the same runway.

h. Precision Approach Path Indicator (PAPI)− Anairport lighting facility, similar to VASI, providingvertical approach slope guidance to aircraft duringapproach to landing. PAPIs consist of a single row of

either two or four lights, normally installed on the leftside of the runway, and have an effective visual rangeof about 5 miles during the day and up to 20 miles atnight. PAPIs radiate a directional pattern of highintensity red and white focused light beams whichindicate that the pilot is “on path” if the pilot sees anequal number of white lights and red lights, withwhite to the left of the red; “above path” if the pilotsees more white than red lights; and “below path” ifthe pilot sees more red than white lights.

i. Boundary Lights− Lights defining the perimeterof an airport or landing area.

(Refer to AIM.)

AIRPORT MARKING AIDS− Markings used onrunway and taxiway surfaces to identify a specificrunway, a runway threshold, a centerline, a hold line,etc. A runway should be marked in accordance withits present usage such as:

a. Visual.

b. Nonprecision instrument.c. Precision instrument.(Refer to AIM.)

AIRPORT REFERENCE POINT (ARP)− Theapproximate geometric center of all usable runwaysurfaces.

AIRPORT RESERVATION OFFICE− Officeresponsible for monitoring the operation of slotcontrolled airports. It receives and processes requestsfor unscheduled operations at slot controlled airports.

AIRPORT ROTATING BEACON− A visualNAVAID operated at many airports. At civil airports,alternating white and green flashes indicate thelocation of the airport. At military airports, thebeacons flash alternately white and green, but aredifferentiated from civil beacons by dualpeaked (twoquick) white flashes between the green flashes.

(See INSTRUMENT FLIGHT RULES.)(See SPECIAL VFR OPERATIONS.)(See ICAO term AERODROME BEACON.)(Refer to AIM.)

AIRPORT STREAM FILTER (ASF)− An on/offfilter that allows the conflict notification function tobe inhibited for arrival streams into single or multipleairports to prevent nuisance alerts.

AIRPORT SURFACE DETECTION EQUIPMENT(ASDE)− Surveillance equipment specifically de-signed to detect aircraft, vehicular traffic, and otherobjects, on the surface of an airport, and to present the



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image on a tower display. Used to augment visualobservation by tower personnel of aircraft and/orvehicular movements on runways and taxiways.There are three ASDE systems deployed in the NAS:

a. ASDE−3− a Surface Movement Radar.

b. ASDE−X− a system that uses an X−bandSurface Movement Radar, multilateration, andADS−B.

c. Airport Surface Surveillance Capability(ASSC)− A system that uses Surface MovementRadar, multilateration, and ADS−B.

AIRPORT SURVEILLANCE RADAR− Approachcontrol radar used to detect and display an aircraft’sposition in the terminal area. ASR provides range andazimuth information but does not provide elevationdata. Coverage of the ASR can extend up to 60 miles.

AIRPORT TAXI CHARTS−(See AERONAUTICAL CHART.)

AIRPORT TRAFFIC CONTROL SERVICE− Aservice provided by a control tower for aircraftoperating on the movement area and in the vicinity ofan airport.

(See MOVEMENT AREA.)(See TOWER.)(See ICAO term AERODROME CONTROLSERVICE.)

AIRPORT TRAFFIC CONTROL TOWER−(See TOWER.)

AIRSPACE CONFLICT− Predicted conflict of anaircraft and active Special Activity Airspace (SAA).

AIRSPACE FLOW PROGRAM (AFP)− AFP is aTraffic Management (TM) process administered bythe Air Traffic Control System Command Center(ATCSCC) where aircraft are assigned an ExpectDeparture Clearance Time (EDCT) in order tomanage capacity and demand for a specific area of theNational Airspace System (NAS). The purpose of theprogram is to mitigate the effects of en routeconstraints. It is a flexible program and may beimplemented in various forms depending upon theneeds of the air traffic system.

AIRSPACE HIERARCHY− Within the airspaceclasses, there is a hierarchy and, in the event of anoverlap of airspace: Class A preempts Class B, ClassB preempts Class C, Class C preempts Class D, ClassD preempts Class E, and Class E preempts Class G.

AIRSPEED− The speed of an aircraft relative to itssurrounding air mass. The unqualified term“airspeed” means one of the following:

a. Indicated Airspeed− The speed shown on theaircraft airspeed indicator. This is the speed used inpilot/controller communications under the generalterm “airspeed.”

(Refer to 14 CFR Part 1.)

b. True Airspeed− The airspeed of an aircraftrelative to undisturbed air. Used primarily in flightplanning and en route portion of flight. When used inpilot/controller communications, it is referred to as“true airspeed” and not shortened to “airspeed.”

AIRSTART− The starting of an aircraft engine whilethe aircraft is airborne, preceded by engine shutdownduring training flights or by actual engine failure.

AIRWAY− A Class E airspace area established in theform of a corridor, the centerline of which is definedby radio navigational aids.

(See FEDERAL AIRWAYS.)(See ICAO term AIRWAY.)(Refer to 14 CFR Part 71.)(Refer to AIM.)

AIRWAY [ICAO]− A control area or portion thereofestablished in the form of corridor equipped withradio navigational aids.

AIRWAY BEACON− Used to mark airway segmentsin remote mountain areas. The light flashes MorseCode to identify the beacon site.

(Refer to AIM.)

AIT−(See AUTOMATED INFORMATIONTRANSFER.)

ALERFA (Alert Phase) [ICAO]− A situation whereinapprehension exists as to the safety of an aircraft andits occupants.

ALERT− A notification to a position that thereis an aircraft-to-aircraft or aircraft-to-airspaceconflict, as detected by Automated ProblemDetection (APD).

ALERT AREA−(See SPECIAL USE AIRSPACE.)

ALERT NOTICE (ALNOT)− A request originatedby a flight service station (FSS) or an air route trafficcontrol center (ARTCC) for an extensive commu-nication search for overdue, unreported, or missingaircraft.



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ALERTING SERVICE− A service provided to notifyappropriate organizations regarding aircraft in needof search and rescue aid and assist such organizationsas required.

ALNOT−(See ALERT NOTICE.)

ALONG−TRACK DISTANCE (ATD)− The hori-zontal distance between the aircraft’s current positionand a fix measured by an area navigation system thatis not subject to slant range errors.

ALPHANUMERIC DISPLAY− Letters and numer-als used to show identification, altitude, beacon code,and other information concerning a target on a radardisplay.

(See AUTOMATED RADAR TERMINALSYSTEMS.)

ALTERNATE AERODROME [ICAO]− An aero-drome to which an aircraft may proceed when itbecomes either impossible or inadvisable to proceedto or to land at the aerodrome of intended landing.

Note: The aerodrome from which a flight departsmay also be an en-route or a destination alternateaerodrome for the flight.

ALTERNATE AIRPORT− An airport at which anaircraft may land if a landing at the intended airportbecomes inadvisable.

(See ICAO term ALTERNATE AERODROME.)

ALTIMETER SETTING− The barometric pressurereading used to adjust a pressure altimeter forvariations in existing atmospheric pressure or to thestandard altimeter setting (29.92).

(Refer to 14 CFR Part 91.)(Refer to AIM.)

ALTITUDE− The height of a level, point, or objectmeasured in feet Above Ground Level (AGL) or fromMean Sea Level (MSL).

(See FLIGHT LEVEL.)

a. MSL Altitude− Altitude expressed in feetmeasured from mean sea level.

b. AGL Altitude− Altitude expressed in feetmeasured above ground level.

c. Indicated Altitude− The altitude as shown by analtimeter. On a pressure or barometric altimeter it isaltitude as shown uncorrected for instrument error

and uncompensated for variation from standardatmospheric conditions.

(See ICAO term ALTITUDE.)

ALTITUDE [ICAO]− The vertical distance of a level,a point or an object considered as a point, measuredfrom mean sea level (MSL).

ALTITUDE READOUT− An aircraft’s altitude,transmitted via the Mode C transponder feature, thatis visually displayed in 100-foot increments on aradar scope having readout capability.

(See ALPHANUMERIC DISPLAY.)(See AUTOMATED RADAR TERMINALSYSTEMS.)

(Refer to AIM.)

ALTITUDE RESERVATION (ALTRV)− Airspaceutilization under prescribed conditions normallyemployed for the mass movement of aircraft or otherspecial user requirements which cannot otherwise beaccomplished. ALTRVs are approved by theappropriate FAA facility.

(See AIR TRAFFIC CONTROL SYSTEMCOMMAND CENTER.)

ALTITUDE RESTRICTION− An altitude or alti-tudes, stated in the order flown, which are to bemaintained until reaching a specific point or time.Altitude restrictions may be issued by ATC due totraffic, terrain, or other airspace considerations.

ALTITUDE RESTRICTIONS ARE CANCELED−Adherence to previously imposed altitude restric-tions is no longer required during a climb or descent.

ALTRV−(See ALTITUDE RESERVATION.)

AMVER−(See AUTOMATED MUTUAL-ASSISTANCEVESSEL RESCUE SYSTEM.)

APB−(See AUTOMATED PROBLEM DETECTIONBOUNDARY.)

APD−(See AUTOMATED PROBLEM DETECTION.)

APDIA−(See AUTOMATED PROBLEM DETECTIONINHIBITED AREA.)

APPROACH CLEARANCE− Authorization byATC for a pilot to conduct an instrument approach.The type of instrument approach for which a



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clearance and other pertinent information is providedin the approach clearance when required.

(See CLEARED APPROACH.)(See INSTRUMENT APPROACHPROCEDURE.)

(Refer to AIM.)(Refer to 14 CFR Part 91.)

APPROACH CONTROL FACILITY− A terminalATC facility that provides approach control service ina terminal area.

(See APPROACH CONTROL SERVICE.)(See RADAR APPROACH CONTROLFACILITY.)

APPROACH CONTROL SERVICE− Air trafficcontrol service provided by an approach controlfacility for arriving and departing VFR/IFR aircraftand, on occasion, en route aircraft. At some airportsnot served by an approach control facility, theARTCC provides limited approach control service.

(See ICAO term APPROACH CONTROLSERVICE.)

(Refer to AIM.)

APPROACH CONTROL SERVICE [ICAO]− Airtraffic control service for arriving or departingcontrolled flights.

APPROACH GATE− An imaginary point usedwithin ATC as a basis for vectoring aircraft to thefinal approach course. The gate will be establishedalong the final approach course 1 mile from the finalapproach fix on the side away from the airport andwill be no closer than 5 miles from the landingthreshold.

APPROACH/DEPARTURE HOLD AREA− Thelocations on taxiways in the approach or departureareas of a runway designated to protect landing ordeparting aircraft. These locations are identified bysigns and markings.

APPROACH LIGHT SYSTEM−(See AIRPORT LIGHTING.)

APPROACH SEQUENCE− The order in whichaircraft are positioned while on approach or awaitingapproach clearance.

(See LANDING SEQUENCE.)(See ICAO term APPROACH SEQUENCE.)

APPROACH SEQUENCE [ICAO]− The order inwhich two or more aircraft are cleared to approach toland at the aerodrome.

APPROACH SPEED− The recommended speedcontained in aircraft manuals used by pilots whenmaking an approach to landing. This speed will varyfor different segments of an approach as well as foraircraft weight and configuration.

APPROACH WITH VERTICAL GUIDANCE(APV)– A term used to describe RNAV approachprocedures that provide lateral and vertical guidancebut do not meet the requirements to be considered aprecision approach.

APPROPRIATE ATS AUTHORITY [ICAO]− Therelevant authority designated by the State responsiblefor providing air traffic services in the airspaceconcerned. In the United States, the “appropriate ATSauthority” is the Program Director for Air TrafficPlanning and Procedures, ATP-1.

APPROPRIATE AUTHORITY−a. Regarding flight over the high seas: the relevant

authority is the State of Registry.b. Regarding flight over other than the high seas:

the relevant authority is the State having sovereigntyover the territory being overflown.

APPROPRIATE OBSTACLE CLEARANCEMINIMUM ALTITUDE− Any of the following:

(See MINIMUM EN ROUTE IFR ALTITUDE.)(See MINIMUM IFR ALTITUDE.)(See MINIMUM OBSTRUCTION CLEARANCEALTITUDE.)

(See MINIMUM VECTORING ALTITUDE.)

APPROPRIATE TERRAIN CLEARANCEMINIMUM ALTITUDE− Any of the following:

(See MINIMUM EN ROUTE IFR ALTITUDE.)(See MINIMUM IFR ALTITUDE.)(See MINIMUM OBSTRUCTION CLEARANCEALTITUDE.)

(See MINIMUM VECTORING ALTITUDE.)

APRON− A defined area on an airport or heliportintended to accommodate aircraft for purposes ofloading or unloading passengers or cargo, refueling,parking, or maintenance. With regard to seaplanes, aramp is used for access to the apron from the water.

(See ICAO term APRON.)

APRON [ICAO]− A defined area, on a landaerodrome, intended to accommodate aircraft forpurposes of loading or unloading passengers, mail orcargo, refueling, parking or maintenance.

ARC− The track over the ground of an aircraft flyingat a constant distance from a navigational aid byreference to distance measuring equipment (DME).



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AREA CONTROL CENTER [ICAO]− An air trafficcontrol facility primarily responsible for ATCservices being provided IFR aircraft during the enroute phase of flight. The U.S. equivalent facility isan air route traffic control center (ARTCC).

AREA NAVIGATION (RNAV)− A method ofnavigation which permits aircraft operation on anydesired flight path within the coverage of ground− orspace−based navigation aids or within the limits ofthe capability of self-contained aids, or a combinationof these.

Note: Area navigation includesperformance−based navigation as well as otheroperations that do not meet the definition ofperformance−based navigation.

AREA NAVIGATION (RNAV) APPROACHCONFIGURATION:

a. STANDARD T− An RNAV approach whosedesign allows direct flight to any one of three initialapproach fixes (IAF) and eliminates the need forprocedure turns. The standard design is to align theprocedure on the extended centerline with the missedapproach point (MAP) at the runway threshold, thefinal approach fix (FAF), and the initial approach/intermediate fix (IAF/IF). The other two IAFs will beestablished perpendicular to the IF.

b. MODIFIED T− An RNAV approach design forsingle or multiple runways where terrain oroperational constraints do not allow for the standardT. The “T” may be modified by increasing ordecreasing the angle from the corner IAF(s) to the IFor by eliminating one or both corner IAFs.

c. STANDARD I− An RNAV approach design fora single runway with both corner IAFs eliminated.Course reversal or radar vectoring may be required atbusy terminals with multiple runways.

d. TERMINAL ARRIVAL AREA (TAA)− TheTAA is controlled airspace established in conjunctionwith the Standard or Modified T and I RNAVapproach configurations. In the standard TAA, thereare three areas: straight-in, left base, and right base.The arc boundaries of the three areas of the TAA arepublished portions of the approach and allow aircraftto transition from the en route structure direct to thenearest IAF. TAAs will also eliminate or reducefeeder routes, departure extensions, and procedureturns or course reversal.

1. STRAIGHT-IN AREA− A 30NM arccentered on the IF bounded by a straight lineextending through the IF perpendicular to theintermediate course.

2. LEFT BASE AREA− A 30NM arc centeredon the right corner IAF. The area shares a boundarywith the straight-in area except that it extends out for30NM from the IAF and is bounded on the other sideby a line extending from the IF through the FAF to thearc.

3. RIGHT BASE AREA− A 30NM arc centeredon the left corner IAF. The area shares a boundarywith the straight-in area except that it extends out for30NM from the IAF and is bounded on the other sideby a line extending from the IF through the FAF to thearc.

AREA NAVIGATION (RNAV) GLOBALPOSITIONING SYSTEM (GPS) PRECISIONRUNWAY MONITORING (PRM) APPROACH– A GPS approach, which requires vertical guidance,used in lieu of another type of PRM approach toconduct approaches to parallel runways whoseextended centerlines are separated by less than 4,300feet and at least 3,000 feet, where simultaneous closeparallel approaches are permitted. Also used in lieuof an ILS PRM and/or LDA PRM approach toconduct Simultaneous Offset Instrument Approach(SOIA) operations.

ARINC− An acronym for Aeronautical Radio, Inc.,a corporation largely owned by a group of airlines.ARINC is licensed by the FCC as an aeronauticalstation and contracted by the FAA to providecommunications support for air traffic control andmeteorological services in portions of internationalairspace.

ARMY AVIATION FLIGHT INFORMATIONBULLETIN− A bulletin that provides air operationdata covering Army, National Guard, and ArmyReserve aviation activities.

ARO−(See AIRPORT RESERVATION OFFICE.)

ARRESTING SYSTEM− A safety device consistingof two major components, namely, engaging orcatching devices and energy absorption devices forthe purpose of arresting both tailhook and/ornontailhook-equipped aircraft. It is used to preventaircraft from overrunning runways when the aircraftcannot be stopped after landing or during aborted



PCG A−13

takeoff. Arresting systems have various names; e.g.,arresting gear, hook device, wire barrier cable.

(See ABORT.)(Refer to AIM.)

ARRIVAL AIRCRAFT INTERVAL− An internallygenerated program in hundredths of minutes basedupon the AAR. AAI is the desired optimum intervalbetween successive arrival aircraft over the vertex.

ARRIVAL CENTER− The ARTCC having jurisdic-tion for the impacted airport.

ARRIVAL DELAY− A parameter which specifies aperiod of time in which no aircraft will be metered forarrival at the specified airport.

ARRIVAL SECTOR− An operational control sectorcontaining one or more meter fixes.

ARRIVAL SECTOR ADVISORY LIST− Anordered list of data on arrivals displayed at thePVD/MDM of the sector which controls the meterfix.

ARRIVAL SEQUENCING PROGRAM− The auto-mated program designed to assist in sequencingaircraft destined for the same airport.

ARRIVAL TIME− The time an aircraft touches downon arrival.

ARSR−(See AIR ROUTE SURVEILLANCE RADAR.)

ARTCC−(See AIR ROUTE TRAFFIC CONTROLCENTER.)

ARTS−(See AUTOMATED RADAR TERMINALSYSTEMS.)

ASDA−(See ACCELERATE-STOP DISTANCEAVAILABLE.)

ASDA [ICAO]−(See ICAO Term ACCELERATE-STOPDISTANCE AVAILABLE.)

ASDE−(See AIRPORT SURFACE DETECTIONEQUIPMENT.)

ASF−(See AIRPORT STREAM FILTER.)

ASLAR−(See AIRCRAFT SURGE LAUNCH ANDRECOVERY.)

ASP−(See ARRIVAL SEQUENCING PROGRAM.)

ASR−(See AIRPORT SURVEILLANCE RADAR.)

ASR APPROACH−(See SURVEILLANCE APPROACH.)

ASSOCIATED− A radar target displaying a datablock with flight identification and altitudeinformation.

(See UNASSOCIATED.)

ATC−(See AIR TRAFFIC CONTROL.)

ATC ADVISES− Used to prefix a message ofnoncontrol information when it is relayed to anaircraft by other than an air traffic controller.

(See ADVISORY.)

ATC ASSIGNED AIRSPACE− Airspace of definedvertical/lateral limits, assigned by ATC, for thepurpose of providing air traffic segregation betweenthe specified activities being conducted within theassigned airspace and other IFR air traffic.

(See SPECIAL USE AIRSPACE.)

ATC CLEARANCE−(See AIR TRAFFIC CLEARANCE.)

ATC CLEARS− Used to prefix an ATC clearancewhen it is relayed to an aircraft by other than an airtraffic controller.

ATC INSTRUCTIONS− Directives issued by airtraffic control for the purpose of requiring a pilot totake specific actions; e.g., “Turn left heading two fivezero,” “Go around,” “Clear the runway.”


ATC PREFERRED ROUTE NOTIFICATION−EDST notification to the appropriate controller of theneed to determine if an ATC preferred route needs tobe applied, based on destination airport.

(See ROUTE ACTION NOTIFICATION.)(See EN ROUTE DECISION SUPPORT TOOL.)

ATC PREFERRED ROUTES− Preferred routes thatare not automatically applied by Host.

ATC REQUESTS− Used to prefix an ATC requestwhen it is relayed to an aircraft by other than an airtraffic controller.



PCG A−14

ATC SECURITY SERVICES− Communicationsand security tracking provided by an ATC facility insupport of the DHS, the DOD, or other Federalsecurity elements in the interest of national security.Such security services are only applicable withindesignated areas. ATC security services do notinclude ATC basic radar services or flight following.

ATC SECURITY SERVICES POSITION− Theposition responsible for providing ATC securityservices as defined. This position does not provideATC, IFR separation, or VFR flight followingservices, but is responsible for providing securityservices in an area comprising airspace assigned toone or more ATC operating sectors. This positionmay be combined with control positions.

ATC SECURITY TRACKING− The continuoustracking of aircraft movement by an ATC facility insupport of the DHS, the DOD, or other securityelements for national security using radar (i.e., radartracking) or other means (e.g., manual tracking)without providing basic radar services (includingtraffic advisories) or other ATC services not definedin this section.

ATS SURVEILLANCE SERVICE [ICAO]– A termused to indicate a service provided directly by meansof an ATS surveillance system.

ATC SURVEILLANCE SOURCE– Used by ATCfor establishing identification, control and separationusing a target depicted on an air traffic controlfacility’s video display that has met the relevantsafety standards for operational use and receivedfrom one, or a combination, of the followingsurveillance sources:a. Radar (See RADAR.)b. ADS-B (See AUTOMATIC DEPENDENTSURVEILLANCE−BROADCAST.)c. WAM (See WIDE AREA MULTILATERATION.)

(See INTERROGATOR.)(See TRANSPONDER.)(See ICAO term RADAR.)(Refer to AIM.)

ATS SURVEILLANCE SYSTEM [ICAO]– Ageneric term meaning variously, ADS−B, PSR, SSRor any comparable ground−based system that enablesthe identification of aircraft.

Note: A comparable ground−based system is onethat has been demonstrated, by comparativeassessment or other methodology, to have a level

of safety and performance equal to or better thanmonopulse SSR.

ATCAA−(See ATC ASSIGNED AIRSPACE.)

ATCRBS−(See RADAR.)

ATCSCC−(See AIR TRAFFIC CONTROL SYSTEMCOMMAND CENTER.)

ATCT−(See TOWER.)

ATD−(See ALONG−TRACK DISTANCE.)

ATIS−(See AUTOMATIC TERMINAL INFORMATIONSERVICE.)

ATIS [ICAO]−(See ICAO Term AUTOMATIC TERMINALINFORMATION SERVICE.)

ATS ROUTE [ICAO]− A specified route designed forchanneling the flow of traffic as necessary for theprovision of air traffic services.

Note: The term “ATS Route” is used to meanvariously, airway, advisory route, controlled oruncontrolled route, arrival or departure, etc.

ATTENTION ALL USERS PAGE (AAUP)- TheAAUP provides the pilot with additional informationrelative to conducting a specific operation, forexample, PRM approaches and RNAV departures.

AUTOLAND APPROACH−An autoland systemaids by providing control of aircraft systems duringa precision instrument approach to at least decisionaltitude and possibly all the way to touchdown, aswell as in some cases, through the landing rollout.The autoland system is a sub-system of the autopilotsystem from which control surface managementoccurs. The aircraft autopilot sends instructions to theautoland system and monitors the autoland systemperformance and integrity during its execution.

AUTOMATED INFORMATION TRANSFER(AIT)− A precoordinated process, specificallydefined in facility directives, during which a transferof altitude control and/or radar identification isaccomplished without verbal coordination betweencontrollers using information communicated in a fulldata block.

AUTOMATED MUTUAL-ASSISTANCE VESSELRESCUE SYSTEM− A facility which can deliver, in



PCG A−15

a matter of minutes, a surface picture (SURPIC) ofvessels in the area of a potential or actual search andrescue incident, including their predicted positionsand their characteristics.

(See FAA Order JO 7110.65, Para 10−6−4,INFLIGHT CONTINGENCIES.)

AUTOMATED PROBLEM DETECTION (APD)−An Automation Processing capability that comparestrajectories in order to predict conflicts.

AUTOMATED PROBLEM DETECTIONBOUNDARY (APB)− The adapted distance beyonda facilities boundary defining the airspace withinwhich EDST performs conflict detection.

(See EN ROUTE DECISION SUPPORT TOOL.)

AUTOMATED PROBLEM DETECTION INHIB-ITED AREA (APDIA)− Airspace surrounding aterminal area within which APD is inhibited for allflights within that airspace.

AUTOMATED RADAR TERMINAL SYSTEMS(ARTS)− A generic term for several tracking systemsincluded in the Terminal Automation Systems (TAS).ARTS plus a suffix roman numeral denotes a majormodification to that system.

a. ARTS IIIA. The Radar Tracking and BeaconTracking Level (RT&BTL) of the modular, program-mable automated radar terminal system. ARTS IIIAdetects, tracks, and predicts primary as well assecondary radar-derived aircraft targets. This moresophisticated computer-driven system upgrades theexisting ARTS III system by providing improvedtracking, continuous data recording, and fail-softcapabilities.

b. Common ARTS. Includes ARTS IIE, ARTSIIIE; and ARTS IIIE with ACD (see DTAS) whichcombines functionalities of the previous ARTSsystems.

AUTOMATED WEATHER SYSTEM− Any of theautomated weather sensor platforms that collectweather data at airports and disseminate the weatherinformation via radio and/or landline. The systemscurrently consist of the Automated Surface Observ-ing System (ASOS) and Automated WeatherObservation System (AWOS).

AUTOMATED UNICOM− Provides completelyautomated weather, radio check capability and airport

advisory information on an Automated UNICOMsystem. These systems offer a variety of features,typically selectable by microphone clicks, on theUNICOM frequency. Availability will be publishedin the Chart Supplement U.S. and approach charts.

AUTOMATIC ALTITUDE REPORT−(See ALTITUDE READOUT.)

AUTOMATIC ALTITUDE REPORTING− Thatfunction of a transponder which responds to Mode Cinterrogations by transmitting the aircraft’s altitudein 100-foot increments.

AUTOMATIC CARRIER LANDING SYSTEM−U.S. Navy final approach equipment consisting ofprecision tracking radar coupled to a computer datalink to provide continuous information to the aircraft,monitoring capability to the pilot, and a backupapproach system.

AUTOMATIC DEPENDENT SURVEILLANCE(ADS) [ICAO]− A surveillance technique in whichaircraft automatically provide, via a data link, dataderived from on−board navigation and positionfixing systems, including aircraft identification, fourdimensional position and additional data asappropriate.

AUTOMATIC DEPENDENT SURVEILLANCE−BROADCAST (ADS-B)− A surveillance system inwhich an aircraft or vehicle to be detected is fittedwith cooperative equipment in the form of a data linktransmitter. The aircraft or vehicle periodicallybroadcasts its GNSS−derived position and otherrequired information such as identity and velocity,which is then received by a ground−based orspace−based receiver for processing and display at anair traffic control facility, as well as by suitablyequipped aircraft.

(See AUTOMATIC DEPENDENTSURVEILLANCE−BROADCAST IN.)

(See AUTOMATIC DEPENDENTSURVEILLANCE−BROADCAST OUT.)

(See COOPERATIVE SURVEILLANCE.)(See GLOBAL POSITIONING SYSTEM.)(See SPACE−BASED ADS−B.)

AUTOMATIC DEPENDENT SURVEILLANCE−BROADCAST IN (ADS−B In)− Aircraft avionicscapable of receiving ADS−B Out transmissionsdirectly from other aircraft, as well as traffic or



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weather information transmitted from groundstations.


(See AUTOMATIC DEPENDENTSURVEILLANCE−REBROADCAST.)

(See FLIGHT INFORMATIONSERVICE−BROADCAST.)

(See TRAFFIC INFORMATIONSERVICE−BROADCAST.)

AUTOMATIC DEPENDENT SURVEILLANCE−BROADCAST OUT (ADS−B Out)− The transmitteronboard an aircraft or ground vehicle thatperiodically broadcasts its GNSS−derived positionalong with other required information, such asidentity, altitude, and velocity.

(See AUTOMATIC DEPENDENTSURVEILLANCE−BROADCAST.)

(See AUTOMATIC DEPENDENTSURVEILLANCE−BROADCAST IN.)

AUTOMATIC DEPENDENT SURVEILLANCE−CONTRACT (ADS−C)− A data link positionreporting system, controlled by a ground station, thatestablishes contracts with an aircraft’s avionics thatoccur automatically whenever specific events occur,or specific time intervals are reached.

AUTOMATIC DEPENDENT SURVEILLANCE-REBROADCAST (ADS-R)− A datalink translationfunction of the ADS−B ground system required toaccommodate the two separate operating frequencies(978 MHz and 1090 MHz). The ADS−B systemreceives the ADS−B messages transmitted on onefrequency and ADS−R translates and reformats theinformation for rebroadcast and use on the otherfrequency. This allows ADS−B In equipped aircraftto see nearby ADS−B Out traffic regardless of theoperating link of the other aircraft. Aircraft operatingon the same ADS−B frequency exchange informationdirectly and do not require the ADS−R translationfunction.

AUTOMATIC DIRECTION FINDER− An aircraftradio navigation system which senses and indicatesthe direction to a L/MF nondirectional radio beacon(NDB) ground transmitter. Direction is indicated tothe pilot as a magnetic bearing or as a relative bearingto the longitudinal axis of the aircraft depending onthe type of indicator installed in the aircraft. In certainapplications, such as military, ADF operations may

be based on airborne and ground transmitters in theVHF/UHF frequency spectrum.

(See BEARING.)(See NONDIRECTIONAL BEACON.)

AUTOMATIC FLIGHT INFORMATION SER-VICE (AFIS) − ALASKA FSSs ONLY− Thecontinuous broadcast of recorded non−controlinformation at airports in Alaska where a FSSprovides local airport advisory service. The AFISbroadcast automates the repetitive transmission ofessential but routine information such as weather,wind, altimeter, favored runway, braking action,airport NOTAMs, and other applicable information.The information is continuously broadcast over adiscrete VHF radio frequency (usually the ASOS/AWOS frequency).

AUTOMATIC TERMINAL INFORMATION SER-VICE− The continuous broadcast of recordednoncontrol information in selected terminal areas. Itspurpose is to improve controller effectiveness and torelieve frequency congestion by automating therepetitive transmission of essential but routineinformation; e.g., “Los Angeles information Alfa.One three zero zero Coordinated Universal Time.Weather, measured ceiling two thousand overcast,visibility three, haze, smoke, temperature seven one,dew point five seven, wind two five zero at five,altimeter two niner niner six. I-L-S Runway Two FiveLeft approach in use, Runway Two Five Right closed,advise you have Alfa.”

(See ICAO term AUTOMATIC TERMINALINFORMATION SERVICE.)

(Refer to AIM.)

AUTOMATIC TERMINAL INFORMATION SER-VICE [ICAO]− The provision of current, routineinformation to arriving and departing aircraft bymeans of continuous and repetitive broadcaststhroughout the day or a specified portion of the day.

AUTOROTATION− A rotorcraft flight condition inwhich the lifting rotor is driven entirely by action ofthe air when the rotorcraft is in motion.

a. Autorotative Landing/Touchdown Autorota-tion. Used by a pilot to indicate that the landing willbe made without applying power to the rotor.

b. Low Level Autorotation. Commences at analtitude well below the traffic pattern, usually below100 feet AGL and is used primarily for tacticalmilitary training.



PCG A−17

c. 180 degrees Autorotation. Initiated from adownwind heading and is commenced well inside thenormal traffic pattern. “Go around” may not bepossible during the latter part of this maneuver.

AVAILABLE LANDING DISTANCE (ALD)− Theportion of a runway available for landing and roll-outfor aircraft cleared for LAHSO. This distance ismeasured from the landing threshold to thehold-short point.

AVIATION WEATHER SERVICE− A serviceprovided by the National Weather Service (NWS) and

FAA which collects and disseminates pertinentweather information for pilots, aircraft operators, andATC. Available aviation weather reports andforecasts are displayed at each NWS office and FAAFSS.

(See TRANSCRIBED WEATHER BROADCAST.)(See WEATHER ADVISORY.)(Refer to AIM.)

AWW−(See SEVERE WEATHER FORECASTALERTS.)



PCG B−1

BBACK-TAXI− A term used by air traffic controllersto taxi an aircraft on the runway opposite to the trafficflow. The aircraft may be instructed to back-taxi tothe beginning of the runway or at some point beforereaching the runway end for the purpose of departureor to exit the runway.

BASE LEG−(See TRAFFIC PATTERN.)

BEACON−(See AERONAUTICAL BEACON.)(See AIRPORT ROTATING BEACON.)(See AIRWAY BEACON.)(See MARKER BEACON.)(See NONDIRECTIONAL BEACON.)(See RADAR.)

BEARING− The horizontal direction to or from anypoint, usually measured clockwise from true north,magnetic north, or some other reference pointthrough 360 degrees.

(See NONDIRECTIONAL BEACON.)

BELOW MINIMUMS− Weather conditions belowthe minimums prescribed by regulation for theparticular action involved; e.g., landing minimums,takeoff minimums.

BLAST FENCE− A barrier that is used to divert ordissipate jet or propeller blast.

BLAST PAD− A surface adjacent to the ends of arunway provided to reduce the erosive effect of jetblast and propeller wash.

BLIND SPEED− The rate of departure or closing ofa target relative to the radar antenna at whichcancellation of the primary radar target by movingtarget indicator (MTI) circuits in the radar equipmentcauses a reduction or complete loss of signal.

(See ICAO term BLIND VELOCITY.)

BLIND SPOT− An area from which radiotransmissions and/or radar echoes cannot bereceived. The term is also used to describe portionsof the airport not visible from the control tower.

BLIND TRANSMISSION−(See TRANSMITTING IN THE BLIND.)

BLIND VELOCITY [ICAO]− The radial velocity ofa moving target such that the target is not seen onprimary radars fitted with certain forms of fixed echosuppression.

BLIND ZONE−(See BLIND SPOT.)

BLOCKED− Phraseology used to indicate that aradio transmission has been distorted or interrupteddue to multiple simultaneous radio transmissions.

BOTTOM ALTITUDE– In reference to publishedaltitude restrictions on a STAR or STAR runwaytransition, the lowest altitude authorized.

BOUNDARY LIGHTS−(See AIRPORT LIGHTING.)

BRAKING ACTION (GOOD, GOOD TO MEDI-UM, MEDIUM, MEDIUM TO POOR, POOR, ORNIL)− A report of conditions on the airportmovement area providing a pilot with a degree/quali-ty of braking to expect. Braking action is reported interms of good, good to medium, medium, medium topoor, poor, or nil.

(See RUNWAY CONDITION READING.)(See RUNWAY CONDITION REPORT.)(See RUNWAY CONDITION CODES.)

BRAKING ACTION ADVISORIES− When towercontrollers receive runway braking action reportswhich include the terms “medium,” “poor,” or “nil,”or whenever weather conditions are conducive todeteriorating or rapidly changing runway brakingconditions, the tower will include on the ATISbroadcast the statement, “Braking Action Advisoriesare in Effect.” During the time braking actionadvisories are in effect, ATC will issue the mostcurrent braking action report for the runway in use toeach arriving and departing aircraft. Pilots should beprepared for deteriorating braking conditions andshould request current runway condition informationif not issued by controllers. Pilots should also beprepared to provide a descriptive runway conditionreport to controllers after landing.

BREAKOUT− A technique to direct aircraft out ofthe approach stream. In the context of simultaneous(independent) parallel operations, a breakout is usedto direct threatened aircraft away from a deviatingaircraft.


PCG B−2

BROADCAST− Transmission of information forwhich an acknowledgement is not expected.

(See ICAO term BROADCAST.)

BROADCAST [ICAO]− A transmission of informa-tion relating to air navigation that is not addressed toa specific station or stations.

BUFFER AREA− As applied to an MVA or MIAchart, a depicted three (3) or five (5) NM radiusMVA/MIA sector isolating a displayed obstacle forwhich the sector is established. A portion of a bufferarea can also be inclusive of a MVA/MIA sectorpolygon boundary.


PCG C−1

CCALCULATED LANDING TIME− A term that maybe used in place of tentative or actual calculatedlanding time, whichever applies.

CALL FOR RELEASE− Wherein the overlyingARTCC requires a terminal facility to initiate verbalcoordination to secure ARTCC approval for releaseof a departure into the en route environment.

CALL UP− Initial voice contact between a facilityand an aircraft, using the identification of the unitbeing called and the unit initiating the call.

(Refer to AIM.)

CANADIAN MINIMUM NAVIGATION PERFOR-MANCE SPECIFICATION AIRSPACE− Thatportion of Canadian domestic airspace within whichMNPS separation may be applied.

CARDINAL ALTITUDES− “Odd” or “Even”thousand-foot altitudes or flight levels; e.g., 5,000,6,000, 7,000, FL 250, FL 260, FL 270.

(See ALTITUDE.)(See FLIGHT LEVEL.)

CARDINAL FLIGHT LEVELS−(See CARDINAL ALTITUDES.)

CAT−(See CLEAR-AIR TURBULENCE.)

CATCH POINT− A fix/waypoint that serves as atransition point from the high altitude waypointnavigation structure to an arrival procedure (STAR)or the low altitude ground−based navigationstructure.

CEILING− The heights above the earth’s surface ofthe lowest layer of clouds or obscuring phenomenathat is reported as “broken,” “overcast,” or“obscuration,” and not classified as “thin” or“partial.”

(See ICAO term CEILING.)

CEILING [ICAO]− The height above the ground orwater of the base of the lowest layer of cloud below6,000 meters (20,000 feet) covering more than halfthe sky.

CENRAP−(See CENTER RADAR ARTSPRESENTATION/PROCESSING.)

CENRAP-PLUS−(See CENTER RADAR ARTSPRESENTATION/PROCESSING-PLUS.)

CENTER−(See AIR ROUTE TRAFFIC CONTROLCENTER.)

CENTER’S AREA− The specified airspace withinwhich an air route traffic control center (ARTCC)provides air traffic control and advisory service.

(See AIR ROUTE TRAFFIC CONTROLCENTER.)

(Refer to AIM.)

CENTER RADAR ARTS PRESENTATION/PROCESSING− A computer program developed toprovide a back-up system for airport surveillanceradar in the event of a failure or malfunction. Theprogram uses air route traffic control center radar forthe processing and presentation of data on the ARTSIIA or IIIA displays.

CENTER RADAR ARTS PRESENTATION/PROCESSING-PLUS− A computer programdeveloped to provide a back-up system for airportsurveillance radar in the event of a terminal secondaryradar system failure. The program uses a combinationof Air Route Traffic Control Center Radar andterminal airport surveillance radar primary targetsdisplayed simultaneously for the processing andpresentation of data on the ARTS IIA or IIIAdisplays.

CENTER TRACON AUTOMATION SYSTEM(CTAS)− A computerized set of programs designedto aid Air Route Traffic Control Centers andTRACONs in the management and control of airtraffic.

CENTER WEATHER ADVISORY− An unsched-uled weather advisory issued by Center WeatherService Unit meteorologists for ATC use to alertpilots of existing or anticipated adverse weatherconditions within the next 2 hours. A CWA maymodify or redefine a SIGMET.

(See AWW.)(See AIRMET.)(See CONVECTIVE SIGMET.)(See SIGMET.)(Refer to AIM.)


PCG C−2

CENTRAL EAST PACIFIC− An organized routesystem between the U.S. West Coast and Hawaii.

CEP−(See CENTRAL EAST PACIFIC.)

CERAP−(See COMBINED CENTER-RAPCON.)

CERTIFIED TOWER RADAR DISPLAY (CTRD)−An FAA radar display certified for use in the NAS.

CFR−(See CALL FOR RELEASE.)

CHA(See CONTINGENCY HAZARD AREA)

CHAFF− Thin, narrow metallic reflectors of variouslengths and frequency responses, used to reflect radarenergy. These reflectors, when dropped from aircraftand allowed to drift downward, result in large targetson the radar display.

CHART SUPPLEMENT U.S.− A publicationdesigned primarily as a pilot’s operational manualcontaining all airports, seaplane bases, and heliportsopen to the public including communications data,navigational facilities, and certain special notices andprocedures. This publication is issued in sevenvolumes according to geographical area.

CHARTED VFR FLYWAYS− Charted VFR Fly-ways are flight paths recommended for use to bypassareas heavily traversed by large turbine-poweredaircraft. Pilot compliance with recommendedflyways and associated altitudes is strictly voluntary.VFR Flyway Planning charts are published on theback of existing VFR Terminal Area charts.

CHARTED VISUAL FLIGHT PROCEDUREAPPROACH− An approach conducted whileoperating on an instrument flight rules (IFR) flightplan which authorizes the pilot of an aircraft toproceed visually and clear of clouds to the airport viavisual landmarks and other information depicted ona charted visual flight procedure. This approach mustbe authorized and under the control of the appropriateair traffic control facility. Weather minimumsrequired are depicted on the chart.

CHASE− An aircraft flown in proximity to anotheraircraft normally to observe its performance duringtraining or testing.

CHASE AIRCRAFT−(See CHASE.)

CHOP− A form of turbulence.

a. Light Chop– Turbulence that causes slight,rapid and somewhat rhythmic bumpiness withoutappreciable changes in altitude or attitude.

b. Moderate Chop– Turbulence similar to LightChop but of greater intensity. It causes rapid bumpsor jolts without appreciable changes in aircraftaltitude or attitude.

(See TURBULENCE.)

CIRCLE-TO-LAND MANEUVER− A maneuverinitiated by the pilot to align the aircraft with arunway for landing when a straight-in landing froman instrument approach is not possible or is notdesirable. At tower controlled airports, this maneuveris made only after ATC authorization has beenobtained and the pilot has established required visualreference to the airport.

(See CIRCLE TO RUNWAY.)(See LANDING MINIMUMS.)(Refer to AIM.)

CIRCLE TO RUNWAY (RUNWAY NUMBER)−Used by ATC to inform the pilot that he/she mustcircle to land because the runway in use is other thanthe runway aligned with the instrument approachprocedure. When the direction of the circlingmaneuver in relation to the airport/runway isrequired, the controller will state the direction (eightcardinal compass points) and specify a left or rightdownwind or base leg as appropriate; e.g., “ClearedVOR Runway Three Six Approach circle to RunwayTwo Two,” or “Circle northwest of the airport for aright downwind to Runway Two Two.”

(See CIRCLE-TO-LAND MANEUVER.)(See LANDING MINIMUMS.)(Refer to AIM.)

CIRCLING APPROACH−(See CIRCLE-TO-LAND MANEUVER.)

CIRCLING MANEUVER−(See CIRCLE-TO-LAND MANEUVER.)

CIRCLING MINIMA−(See LANDING MINIMUMS.)

CLASS A AIRSPACE−(See CONTROLLED AIRSPACE.)

CLASS B AIRSPACE−(See CONTROLLED AIRSPACE.)



PCG C−3

CLASS C AIRSPACE−(See CONTROLLED AIRSPACE.)

CLASS D AIRSPACE−(See CONTROLLED AIRSPACE.)

CLASS E AIRSPACE−(See CONTROLLED AIRSPACE.)

CLASS G AIRSPACE− Airspace that is notdesignated in 14 CFR Part 71 as Class A, Class B,Class C, Class D, or Class E controlled airspace isClass G (uncontrolled) airspace.

(See UNCONTROLLED AIRSPACE.)

CLEAR AIR TURBULENCE (CAT)− Turbulenceencountered in air where no clouds are present. Thisterm is commonly applied to high-level turbulenceassociated with wind shear. CAT is often encounteredin the vicinity of the jet stream.

(See WIND SHEAR.)(See JET STREAM.)

CLEAR OF THE RUNWAY−

a. Taxiing aircraft, which is approaching arunway, is clear of the runway when all parts of theaircraft are held short of the applicable runwayholding position marking.

b. A pilot or controller may consider an aircraft,which is exiting or crossing a runway, to be clear ofthe runway when all parts of the aircraft are beyondthe runway edge and there are no restrictions to itscontinued movement beyond the applicable runwayholding position marking.

c. Pilots and controllers shall exercise goodjudgement to ensure that adequate separation existsbetween all aircraft on runways and taxiways atairports with inadequate runway edge lines orholding position markings.

CLEARANCE−(See AIR TRAFFIC CLEARANCE.)

CLEARANCE LIMIT− The fix, point, or location towhich an aircraft is cleared when issued an air trafficclearance.

(See ICAO term CLEARANCE LIMIT.)

CLEARANCE LIMIT [ICAO]− The point to whichan aircraft is granted an air traffic control clearance.

CLEARANCE VOID IF NOT OFF BY (TIME)−Used by ATC to advise an aircraft that the departureclearance is automatically canceled if takeoff is notmade prior to a specified time. The pilot must obtain

a new clearance or cancel his/her IFR flight plan if notoff by the specified time.

(See ICAO term CLEARANCE VOID TIME.)

CLEARANCE VOID TIME [ICAO]− A timespecified by an air traffic control unit at which aclearance ceases to be valid unless the aircraftconcerned has already taken action to complytherewith.

CLEARED APPROACH− ATC authorization for anaircraft to execute any standard or special instrumentapproach procedure for that airport. Normally, anaircraft will be cleared for a specific instrumentapproach procedure.

(See CLEARED (Type of) APPROACH.)(See INSTRUMENT APPROACHPROCEDURE.)


CLEARED (Type of) APPROACH− ATC authoriza-tion for an aircraft to execute a specific instrumentapproach procedure to an airport; e.g., “Cleared ILSRunway Three Six Approach.”

(See APPROACH CLEARANCE.)(See INSTRUMENT APPROACHPROCEDURE.)


CLEARED AS FILED− Means the aircraft is clearedto proceed in accordance with the route of flight filedin the flight plan. This clearance does not include thealtitude, DP, or DP Transition.

(See REQUEST FULL ROUTE CLEARANCE.)(Refer to AIM.)

CLEARED FOR TAKEOFF− ATC authorizationfor an aircraft to depart. It is predicated on knowntraffic and known physical airport conditions.

CLEARED FOR THE OPTION− ATC authoriza-tion for an aircraft to make a touch-and-go, lowapproach, missed approach, stop and go, or full stoplanding at the discretion of the pilot. It is normallyused in training so that an instructor can evaluate astudent’s performance under changing situations.Pilots should advise ATC if they decide to remain onthe runway, of any delay in their stop and go, delayclearing the runway, or are unable to comply with theinstruction(s).

(See OPTION APPROACH.)(Refer to AIM.)



PCG C−4

CLEARED THROUGH− ATC authorization for anaircraft to make intermediate stops at specifiedairports without refiling a flight plan while en routeto the clearance limit.

CLEARED TO LAND− ATC authorization for anaircraft to land. It is predicated on known traffic andknown physical airport conditions.

CLEARWAY− An area beyond the takeoff runwayunder the control of airport authorities within whichterrain or fixed obstacles may not extend abovespecified limits. These areas may be required forcertain turbine-powered operations and the size andupward slope of the clearway will differ depending onwhen the aircraft was certificated.


CLIMB TO VFR− ATC authorization for an aircraftto climb to VFR conditions within Class B, C, D, andE surface areas when the only weather limitation isrestricted visibility. The aircraft must remain clear ofclouds while climbing to VFR.

(See SPECIAL VFR CONDITIONS.)

(Refer to AIM.)

CLIMBOUT− That portion of flight operationbetween takeoff and the initial cruising altitude.

CLIMB VIA– An abbreviated ATC clearance thatrequires compliance with the procedure lateral path,associated speed restrictions, and altitude restrictionsalong the cleared route or procedure.

CLOSE PARALLEL RUNWAYS− Two parallelrunways whose extended centerlines are separated byless than 4,300 feet and at least 3000 feet (750 feet forSOIA operations) for which ATC is authorized toconduct simultaneous independent approach opera-tions. PRM and simultaneous close parallel appear inapproach title. Dual communications, special pilottraining, an Attention All Users Page (AAUP), NTZmonitoring by displays that have aural and visualalerting algorithms are required. A high update ratesurveillance sensor is required for certain runway orapproach course spacing.

CLOSED RUNWAY− A runway that is unusable foraircraft operations. Only the airport management/military operations office can close a runway.

CLOSED TRAFFIC− Successive operations involv-ing takeoffs and landings or low approaches wherethe aircraft does not exit the traffic pattern.

CLOUD− A cloud is a visible accumulation ofminute water droplets and/or ice particles in theatmosphere above the Earth’s surface. Cloud differsfrom ground fog, fog, or ice fog only in that the latterare, by definition, in contact with the Earth’s surface.

CLT−(See CALCULATED LANDING TIME.)

CLUTTER− In radar operations, clutter refers to thereception and visual display of radar returns causedby precipitation, chaff, terrain, numerous aircrafttargets, or other phenomena. Such returns may limitor preclude ATC from providing services based onradar.

(See CHAFF.)(See GROUND CLUTTER.)(See PRECIPITATION.)(See TARGET.)(See ICAO term RADAR CLUTTER.)

CMNPS−(See CANADIAN MINIMUM NAVIGATIONPERFORMANCE SPECIFICATION AIRSPACE.)

COASTAL FIX− A navigation aid or intersectionwhere an aircraft transitions between the domesticroute structure and the oceanic route structure.

CODES− The number assigned to a particularmultiple pulse reply signal transmitted by atransponder.

(See DISCRETE CODE.)

COLD TEMPERATURE COMPENSATION− Anaction on the part of the pilot to adjust an aircraft’sindicated altitude due to the effect of coldtemperatures on true altitude above terrain versusaircraft indicated altitude. The amount ofcompensation required increases at a greater rate witha decrease in temperature and increase in heightabove the reporting station.

COLLABORATIVE TRAJECTORY OPTIONSPROGRAM (CTOP)− CTOP is a traffic managementprogram administered by the Air Traffic ControlSystem Command Center (ATCSCC) that managesdemand through constrained airspace, while consid-ering operator preference with regard to both routeand delay as defined in a Trajectory Options Set(TOS).


PCG C−5

COMBINED CENTER-RAPCON− An air trafficfacility which combines the functions of an ARTCCand a radar approach control facility.


(See RADAR APPROACH CONTROLFACILITY.)

COMMON POINT− A significant point over whichtwo or more aircraft will report passing or havereported passing before proceeding on the same ordiverging tracks. To establish/maintain longitudinalseparation, a controller may determine a commonpoint not originally in the aircraft’s flight plan andthen clear the aircraft to fly over the point.

(See SIGNIFICANT POINT.)

COMMON PORTION−(See COMMON ROUTE.)

COMMON ROUTE− That segment of a NorthAmerican Route between the inland navigationfacility and the coastal fix.

OR

COMMON ROUTE− Typically the portion of aRNAV STAR between the en route transition endpoint and the runway transition start point; however,the common route may only consist of a single pointthat joins the en route and runway transitions.

COMMON TRAFFIC ADVISORY FREQUENCY(CTAF)− A frequency designed for the purpose ofcarrying out airport advisory practices whileoperating to or from an airport without an operatingcontrol tower. The CTAF may be a UNICOM,Multicom, FSS, or tower frequency and is identifiedin appropriate aeronautical publications.

(See DESIGNATED COMMON TRAFFICADVISORY FREQUENCY (CTAF) AREA.)

(Refer to AC 90-42, Traffic Advisory Practices atAirports Without Operating Control Towers.)

COMPASS LOCATOR− A low power, low ormedium frequency (L/MF) radio beacon installed atthe site of the outer or middle marker of an instrumentlanding system (ILS). It can be used for navigation atdistances of approximately 15 miles or as authorizedin the approach procedure.

a. Outer Compass Locator (LOM)− A compasslocator installed at the site of the outer marker of aninstrument landing system.

(See OUTER MARKER.)

b. Middle Compass Locator (LMM)− A compasslocator installed at the site of the middle marker of aninstrument landing system.

(See MIDDLE MARKER.)(See ICAO term LOCATOR.)

COMPASS ROSE− A circle, graduated in degrees,printed on some charts or marked on the ground at anairport. It is used as a reference to either true ormagnetic direction.

COMPLY WITH RESTRICTIONS− An ATCinstruction that requires an aircraft being vectoredback onto an arrival or departure procedure to complywith all altitude and/or speed restrictions depicted onthe procedure. This term may be used in lieu ofrepeating each remaining restriction that appears onthe procedure.

COMPOSITE FLIGHT PLAN− A flight plan whichspecifies VFR operation for one portion of flight andIFR for another portion. It is used primarily inmilitary operations.

(Refer to AIM.)

COMPULSORY REPORTING POINTS− Reportingpoints which must be reported to ATC. They aredesignated on aeronautical charts by solid triangles orfiled in a flight plan as fixes selected to define directroutes. These points are geographical locationswhich are defined by navigation aids/fixes. Pilotsshould discontinue position reporting over compul-sory reporting points when informed by ATC thattheir aircraft is in “radar contact.”

COMPUTER NAVIGATION FIX (CNF)− AComputer Navigation Fix is a point defined by alatitude/longitude coordinate and is required tosupport Performance−Based Navigation (PBN)operations. A five−letter identifier denoting a CNFcan be found next to an “x” on en route charts and onsome approach charts. Eventually, all CNFs will belabeled and begin with the letters “CF” followed bythree consonants (e.g., ‘CFWBG’). CNFs are notrecognized by ATC, are not contained in ATC fix orautomation databases, and are not used for ATCpurposes. Pilots should not use CNFs for point−to−point navigation (e.g., proceed direct), filing a flightplan, or in aircraft/ATC communications. Use ofCNFs has not been adopted or recognized by theInternational Civil Aviation Organization (ICAO).

(REFER to AIM 1−1−17b5(i)(2), GlobalPositioning System (GPS).


PCG C−6

CONDITIONS NOT MONITORED− When anairport operator cannot monitor the condition of themovement area or airfield surface area, thisinformation is issued as a NOTAM. Usuallynecessitated due to staffing, operating hours or othermitigating factors associated with airport operations.

CONFIDENCE MANEUVER− A confidence man-euver consists of one or more turns, a climb ordescent, or other maneuver to determine if the pilotin command (PIC) is able to receive and comply withATC instructions.

CONFLICT ALERT− A function of certain air trafficcontrol automated systems designed to alert radarcontrollers to existing or pending situations betweentracked targets (known IFR or VFR aircraft) thatrequire his/her immediate attention/action.

(See MODE C INTRUDER ALERT.)

CONFLICT RESOLUTION− The resolution ofpotential conflictions between aircraft that are radaridentified and in communication with ATC byensuring that radar targets do not touch. Pertinenttraffic advisories shall be issued when this procedureis applied.

Note: This procedure shall not be provided utilizingmosaic radar systems.

CONFORMANCE− The condition established whenan aircraft’s actual position is within the conformanceregion constructed around that aircraft at its position,according to the trajectory associated with theaircraft’s Current Plan.

CONFORMANCE REGION− A volume, boundedlaterally, vertically, and longitudinally, within whichan aircraft must be at a given time in order to be inconformance with the Current Plan Trajectory for thataircraft. At a given time, the conformance region isdetermined by the simultaneous application of thelateral, vertical, and longitudinal conformancebounds for the aircraft at the position defined by timeand aircraft’s trajectory.

CONSOLAN− A low frequency, long-distanceNAVAID used principally for transoceanic naviga-tions.

CONTACT−

a. Establish communication with (followed by thename of the facility and, if appropriate, the frequencyto be used).

b. A flight condition wherein the pilot ascertainsthe attitude of his/her aircraft and navigates by visualreference to the surface.

(See CONTACT APPROACH.)(See RADAR CONTACT.)

CONTACT APPROACH− An approach wherein anaircraft on an IFR flight plan, having an air trafficcontrol authorization, operating clear of clouds withat least 1 mile flight visibility and a reasonableexpectation of continuing to the destination airport inthose conditions, may deviate from the instrumentapproach procedure and proceed to the destinationairport by visual reference to the surface. Thisapproach will only be authorized when requested bythe pilot and the reported ground visibility at thedestination airport is at least 1 statute mile.

(Refer to AIM.)

CONTAMINATED RUNWAY− A runway isconsidered contaminated whenever standing water,ice, snow, slush, frost in any form, heavy rubber, orother substances are present. A runway is contami-nated with respect to rubber deposits or otherfriction-degrading substances when the averagefriction value for any 500-foot segment of the runwaywithin the ALD fails below the recommendedminimum friction level and the average friction valuein the adjacent 500-foot segments falls below themaintenance planning friction level.

CONTERMINOUS U.S.− The 48 adjoining Statesand the District of Columbia.

CONTINENTAL UNITED STATES− The 49 Stateslocated on the continent of North America and theDistrict of Columbia.

CONTINGENCY HAZARD AREA (CHA)− Usedby ATC. Areas of airspace that are defined anddistributed in advance of a launch or reentryoperation and are activated in response to a failure.

(See AIRCRAFT HAZARD AREA.)(See REFINED HAZARD AREA.)(See TRANSITIONAL HAZARD AREA.)

CONTINUE− When used as a control instructionshould be followed by another word or wordsclarifying what is expected of the pilot. Example:“continue taxi,” “continue descent,” “continueinbound,” etc.

CONTROL AREA [ICAO]− A controlled airspaceextending upwards from a specified limit above theearth.



PCG C−7

CONTROL SECTOR− An airspace area of definedhorizontal and vertical dimensions for which acontroller or group of controllers has air trafficcontrol responsibility, normally within an air routetraffic control center or an approach control facility.Sectors are established based on predominant trafficflows, altitude strata, and controller workload. Pilotcommunications during operations within a sectorare normally maintained on discrete frequenciesassigned to the sector.

(See DISCRETE FREQUENCY.)

CONTROL SLASH− A radar beacon slash repre-senting the actual position of the associated aircraft.Normally, the control slash is the one closest to theinterrogating radar beacon site. When ARTCC radaris operating in narrowband (digitized) mode, thecontrol slash is converted to a target symbol.

CONTROLLED AIRSPACE− An airspace ofdefined dimensions within which air traffic controlservice is provided to IFR flights and to VFR flightsin accordance with the airspace classification.

a. Controlled airspace is a generic term that coversClass A, Class B, Class C, Class D, and Class Eairspace.

b. Controlled airspace is also that airspace withinwhich all aircraft operators are subject to certain pilotqualifications, operating rules, and equipmentrequirements in 14 CFR Part 91 (for specificoperating requirements, please refer to 14 CFRPart 91). For IFR operations in any class of controlledairspace, a pilot must file an IFR flight plan andreceive an appropriate ATC clearance. Each Class B,Class C, and Class D airspace area designated for anairport contains at least one primary airport aroundwhich the airspace is designated (for specificdesignations and descriptions of the airspace classes,please refer to 14 CFR Part 71).

c. Controlled airspace in the United States isdesignated as follows:

1. CLASS A− Generally, that airspace from18,000 feet MSL up to and including FL 600,including the airspace overlying the waters within 12nautical miles of the coast of the 48 contiguous Statesand Alaska. Unless otherwise authorized, all personsmust operate their aircraft under IFR.

2. CLASS B− Generally, that airspace from thesurface to 10,000 feet MSL surrounding the nation’sbusiest airports in terms of airport operations orpassenger enplanements. The configuration of each

Class B airspace area is individually tailored andconsists of a surface area and two or more layers(some Class B airspace areas resemble upside-downwedding cakes), and is designed to contain allpublished instrument procedures once an aircraftenters the airspace. An ATC clearance is required forall aircraft to operate in the area, and all aircraft thatare so cleared receive separation services within theairspace. The cloud clearance requirement for VFRoperations is “clear of clouds.”

3. CLASS C− Generally, that airspace from thesurface to 4,000 feet above the airport elevation(charted in MSL) surrounding those airports thathave an operational control tower, are serviced by aradar approach control, and that have a certainnumber of IFR operations or passenger enplane-ments. Although the configuration of each Class Carea is individually tailored, the airspace usuallyconsists of a surface area with a 5 nautical mile (NM)radius, a circle with a 10NM radius that extends nolower than 1,200 feet up to 4,000 feet above theairport elevation, and an outer area that is not charted.Each person must establish two-way radio commu-nications with the ATC facility providing air trafficservices prior to entering the airspace and thereaftermaintain those communications while within theairspace. VFR aircraft are only separated from IFRaircraft within the airspace.

(See OUTER AREA.)

4. CLASS D− Generally, that airspace from thesurface to 2,500 feet above the airport elevation(charted in MSL) surrounding those airports thathave an operational control tower. The configurationof each Class D airspace area is individually tailoredand when instrument procedures are published, theairspace will normally be designed to contain theprocedures. Arrival extensions for instrumentapproach procedures may be Class D or Class Eairspace. Unless otherwise authorized, each personmust establish two-way radio communications withthe ATC facility providing air traffic services prior toentering the airspace and thereafter maintain thosecommunications while in the airspace. No separationservices are provided to VFR aircraft.

5. CLASS E− Generally, if the airspace is notClass A, Class B, Class C, or Class D, and it iscontrolled airspace, it is Class E airspace. Class Eairspace extends upward from either the surface or adesignated altitude to the overlying or adjacentcontrolled airspace. When designated as a surface



PCG C−8

area, the airspace will be configured to contain allinstrument procedures. Also in this class are Federalairways, airspace beginning at either 700 or 1,200feet AGL used to transition to/from the terminal or enroute environment, en route domestic, and offshoreairspace areas designated below 18,000 feet MSL.Unless designated at a lower altitude, Class Eairspace begins at 14,500 MSL over the UnitedStates, including that airspace overlying the waterswithin 12 nautical miles of the coast of the 48contiguous States and Alaska, up to, but notincluding 18,000 feet MSL, and the airspace aboveFL 600.

CONTROLLED AIRSPACE [ICAO]− An airspaceof defined dimensions within which air traffic controlservice is provided to IFR flights and to VFR flightsin accordance with the airspace classification.

Note: Controlled airspace is a generic term whichcovers ATS airspace Classes A, B, C, D, and E.

CONTROLLED TIME OF ARRIVAL− Arrival timeassigned during a Traffic Management Program. Thistime may be modified due to adjustments or useroptions.

CONTROLLER−(See AIR TRAFFIC CONTROL SPECIALIST.)

CONTROLLER [ICAO]− A person authorized toprovide air traffic control services.

CONTROLLER PILOT DATA LINKCOMMUNICATIONS (CPDLC)− A two−waydigital communications system that conveys textualair traffic control messages between controllers andpilots using ground or satellite-based radio relaystations.

CONVECTIVE SIGMET− A weather advisoryconcerning convective weather significant to thesafety of all aircraft. Convective SIGMETs are issuedfor tornadoes, lines of thunderstorms, embeddedthunderstorms of any intensity level, areas ofthunderstorms greater than or equal to VIP level 4with an area coverage of 4/10 (40%) or more, and hail3/4 inch or greater.

(See AIRMET.)(See AWW.)(See CWA.)(See SIGMET.)(Refer to AIM.)

CONVECTIVE SIGNIFICANT METEOROLOG-ICAL INFORMATION−

(See CONVECTIVE SIGMET.)

COOPERATIVE SURVEILLANCE− Any surveil-lance system, such as secondary surveillance radar(SSR), wide−area multilateration (WAM), or ADS−B, that is dependent upon the presence of certainequipment onboard the aircraft or vehicle to bedetected.


(See NON−COOPERATIVE SURVEILLANCE.)(See RADAR.)(See WIDE AREA MULTILATERATION.)

COORDINATES− The intersection of lines ofreference, usually expressed in degrees/minutes/seconds of latitude and longitude, used to determineposition or location.

COORDINATION FIX− The fix in relation to whichfacilities will handoff, transfer control of an aircraft,or coordinate flight progress data. For terminalfacilities, it may also serve as a clearance for arrivingaircraft.

COPTER−(See HELICOPTER.)

CORRECTION− An error has been made in thetransmission and the correct version follows.

COUPLED APPROACH− An instrument approachperformed by the aircraft autopilot, and/or visuallydepicted on the flight director, which is receivingposition information and/or steering commands fromonboard navigational equipment. In general, couplednon-precision approaches must be flown manually(autopilot disengaged) at altitudes lower than 50 feetAGL below the minimum descent altitude, andcoupled precision approaches must be flownmanually (autopilot disengaged) below 50 feet AGLunless authorized to conduct autoland operations.Coupled instrument approaches are commonly flownto the allowable IFR weather minima established bythe operator or PIC, or flown VFR for training andsafety.

COURSE−

a. The intended direction of flight in the horizontalplane measured in degrees from north.



PCG C−9

b. The ILS localizer signal pattern usuallyspecified as the front course or the back course.

(See BEARING.)(See INSTRUMENT LANDING SYSTEM.)(See RADIAL.)

CPDLC−(See CONTROLLER PILOT DATA LINKCOMMUNICATIONS.)

CPL [ICAO]−(See ICAO term CURRENT FLIGHT PLAN.)

CRITICAL ENGINE− The engine which, uponfailure, would most adversely affect the performanceor handling qualities of an aircraft.

CROSS (FIX) AT (ALTITUDE)− Used by ATCwhen a specific altitude restriction at a specified fixis required.

CROSS (FIX) AT OR ABOVE (ALTITUDE)− Usedby ATC when an altitude restriction at a specified fixis required. It does not prohibit the aircraft fromcrossing the fix at a higher altitude than specified;however, the higher altitude may not be one that willviolate a succeeding altitude restriction or altitudeassignment.

(See ALTITUDE RESTRICTION.)(Refer to AIM.)

CROSS (FIX) AT OR BELOW (ALTITUDE)−Used by ATC when a maximum crossing altitude ata specific fix is required. It does not prohibit theaircraft from crossing the fix at a lower altitude;however, it must be at or above the minimum IFRaltitude.

(See ALTITUDE RESTRICTION.)(See MINIMUM IFR ALTITUDES.)(Refer to 14 CFR Part 91.)

CROSSWIND−

a. When used concerning the traffic pattern, theword means “crosswind leg.”

(See TRAFFIC PATTERN.)

b. When used concerning wind conditions, theword means a wind not parallel to the runway or thepath of an aircraft.

(See CROSSWIND COMPONENT.)

CROSSWIND COMPONENT− The wind compo-nent measured in knots at 90 degrees to thelongitudinal axis of the runway.

CRUISE− Used in an ATC clearance to authorize apilot to conduct flight at any altitude from theminimum IFR altitude up to and including thealtitude specified in the clearance. The pilot maylevel off at any intermediate altitude within this blockof airspace. Climb/descent within the block is to bemade at the discretion of the pilot. However, once thepilot starts descent and verbally reports leaving analtitude in the block, he/she may not return to thataltitude without additional ATC clearance. Further, itis approval for the pilot to proceed to and make anapproach at destination airport and can be used inconjunction with:

a. An airport clearance limit at locations with astandard/special instrument approach procedure. TheCFRs require that if an instrument letdown to anairport is necessary, the pilot shall make the letdownin accordance with a standard/special instrumentapproach procedure for that airport, or

b. An airport clearance limit at locations that arewithin/below/outside controlled airspace and with-out a standard/special instrument approachprocedure. Such a clearance is NOT AUTHORIZA-TION for the pilot to descend under IFR conditionsbelow the applicable minimum IFR altitude nor doesit imply that ATC is exercising control over aircraftin Class G airspace; however, it provides a means forthe aircraft to proceed to destination airport, descend,and land in accordance with applicable CFRsgoverning VFR flight operations. Also, this providessearch and rescue protection until such time as theIFR flight plan is closed.

(See INSTRUMENT APPROACHPROCEDURE.)

CRUISE CLIMB− A climb technique employed byaircraft, usually at a constant power setting, resultingin an increase of altitude as the aircraft weightdecreases.

CRUISING ALTITUDE− An altitude or flight levelmaintained during en route level flight. This is aconstant altitude and should not be confused with acruise clearance.

(See ALTITUDE.)(See ICAO term CRUISING LEVEL.)

CRUISING LEVEL−(See CRUISING ALTITUDE.)

CRUISING LEVEL [ICAO]− A level maintainedduring a significant portion of a flight.



PCG C−10

CT MESSAGE− An EDCT time generated by theATCSCC to regulate traffic at arrival airports.Normally, a CT message is automatically transferredfrom the traffic management system computer to theNAS en route computer and appears as an EDCT. Inthe event of a communication failure between thetraffic management system computer and the NAS,the CT message can be manually entered by the TMCat the en route facility.

CTA−(See CONTROLLED TIME OF ARRIVAL.)(See ICAO term CONTROL AREA.)

CTAF−(See COMMON TRAFFIC ADVISORYFREQUENCY.)

CTAS−(See CENTER TRACON AUTOMATIONSYSTEM.)

CTOP−(See COLLABORATIVE TRAJECTORYOPTIONS PROGRAM)

CTRD−(See CERTIFIED TOWER RADAR DISPLAY.)

CURRENT FLIGHT PLAN [ICAO]− The flightplan, including changes, if any, brought about bysubsequent clearances.

CURRENT PLAN− The ATC clearance the aircrafthas received and is expected to fly.

CVFP APPROACH−(See CHARTED VISUAL FLIGHT PROCEDUREAPPROACH.)

CWA−(See CENTER WEATHER ADVISORY andWEATHER ADVISORY.)



PCG D−1

DD−ATIS−

(See DIGITAL-AUTOMATIC TERMINALINFORMATION SERVICE.)

D−ATIS [ICAO]−(See ICAO Term DATA LINK AUTOMATICTERMINAL INFORMATION SERVICE.)

DA [ICAO]−(See ICAO Term DECISIONALTITUDE/DECISION HEIGHT.)

DAIR−(See DIRECT ALTITUDE AND IDENTITYREADOUT.)

DANGER AREA [ICAO]− An airspace of defineddimensions within which activities dangerous to theflight of aircraft may exist at specified times.

Note: The term “Danger Area” is not used inreference to areas within the United States or anyof its possessions or territories.

DAS−(See DELAY ASSIGNMENT.)

DATA BLOCK−(See ALPHANUMERIC DISPLAY.)

DATA LINK AUTOMATIC TERMINAL INFOR-MATION SERVICE (D−ATIS) [ICAO]− Theprovision of ATIS via data link.

DEAD RECKONING− Dead reckoning, as appliedto flying, is the navigation of an airplane solely bymeans of computations based on airspeed, course,heading, wind direction, and speed, groundspeed,and elapsed time.

DECISION ALTITUDE/DECISION HEIGHT[ICAO Annex 6]- A specified altitude or height (A/H)in the precision approach at which a missed approachmust be initiated if the required visual reference tocontinue the approach has not been established. 1. Decision altitude (DA) is referenced to mean sealevel and decision height (DH) is referenced to thethreshold elevation. 2. Category II and III minima are expressed as a DHand not a DA. Minima is assessed by reference to aradio altimeter and not a barometric altimeter, whichmakes the minima a DH.

3. The required visual reference means that section ofthe visual aids or of the approach area which shouldhave been in view for sufficient time for the pilot tohave made an assessment of the aircraft position andrate of change of position, in relation to the desiredflight path.

DECISION ALTITUDE (DA)− A specified altitude(mean sea level (MSL)) on an instrument approachprocedure (ILS, GLS, vertically guided RNAV) atwhich the pilot must decide whether to continue theapproach or initiate an immediate missed approach ifthe pilot does not see the required visual references.

DECISION HEIGHT (DH)− With respect to theoperation of aircraft, means the height at which adecision must be made during an ILS or PARinstrument approach to either continue the approachor to execute a missed approach.

(See ICAO term DECISIONALTITUDE/DECISION HEIGHT.)

DECODER− The device used to decipher signalsreceived from ATCRBS transponders to effect theirdisplay as select codes.

(See CODES.)(See RADAR.)

DEFENSE AREA– Any airspace of the contiguousUnited States that is not an ADIZ in which the controlof aircraft is required for reasons of national security.

DEFENSE VISUAL FLIGHT RULES− Rulesapplicable to flights within an ADIZ conducted underthe visual flight rules in 14 CFR Part 91.

(See AIR DEFENSE IDENTIFICATION ZONE.)(Refer to 14 CFR Part 91.)(Refer to 14 CFR Part 99.)

DELAY ASSIGNMENT (DAS)− Delays are distrib-uted to aircraft based on the traffic managementprogram parameters. The delay assignment iscalculated in 15−minute increments and appears as atable in Traffic Flow Management System (TFMS).

DELAY INDEFINITE (REASON IF KNOWN)EXPECT FURTHER CLEARANCE (TIME)−Used by ATC to inform a pilot when an accurateestimate of the delay time and the reason for the delaycannot immediately be determined; e.g., a disabled


PCG D−2

aircraft on the runway, terminal or center areasaturation, weather below landing minimums, etc.

(See EXPECT FURTHER CLEARANCE (TIME).)

DELAY TIME− The amount of time that the arrivalmust lose to cross the meter fix at the assigned meterfix time. This is the difference between ACLT andVTA.

DEPARTURE CENTER− The ARTCC havingjurisdiction for the airspace that generates a flight tothe impacted airport.

DEPARTURE CONTROL− A function of anapproach control facility providing air traffic controlservice for departing IFR and, under certainconditions, VFR aircraft.

(See APPROACH CONTROL FACILITY.)(Refer to AIM.)

DEPARTURE SEQUENCING PROGRAM− Aprogram designed to assist in achieving a specifiedinterval over a common point for departures.

DEPARTURE TIME− The time an aircraft becomesairborne.

DESCEND VIA– An abbreviated ATC clearance thatrequires compliance with a published procedurelateral path and associated speed restrictions andprovides a pilot-discretion descent to comply withpublished altitude restrictions.

DESCENT SPEED ADJUSTMENTS− Speed decel-eration calculations made to determine an accurateVTA. These calculations start at the transition pointand use arrival speed segments to the vertex.

DESIGNATED COMMON TRAFFIC ADVISORYFREQUENCY (CTAF) AREA− In Alaska, inaddition to being designated for the purpose ofcarrying out airport advisory practices whileoperating to or from an airport without an operatingairport traffic control tower, a CTAF may also bedesignated for the purpose of carrying out advisorypractices for operations in and through areas with ahigh volume of VFR traffic.

DESIRED COURSE−

a. True− A predetermined desired course directionto be followed (measured in degrees from true north).

b. Magnetic− A predetermined desired coursedirection to be followed (measured in degrees fromlocal magnetic north).

DESIRED TRACK− The planned or intended trackbetween two waypoints. It is measured in degreesfrom either magnetic or true north. The instantaneousangle may change from point to point along the greatcircle track between waypoints.

DETRESFA (DISTRESS PHASE) [ICAO]− Thecode word used to designate an emergency phasewherein there is reasonable certainty that an aircraftand its occupants are threatened by grave andimminent danger or require immediate assistance.

DEVIATIONS−

a. A departure from a current clearance, such as anoff course maneuver to avoid weather or turbulence.

b. Where specifically authorized in the CFRs andrequested by the pilot, ATC may permit pilots todeviate from certain regulations.

DH−(See DECISION HEIGHT.)

DH [ICAO]−(See ICAO Term DECISION ALTITUDE/DECISION HEIGHT.)

DIGITAL-AUTOMATIC TERMINAL INFORMA-TION SERVICE (D-ATIS)− The service providestext messages to aircraft, airlines, and other usersoutside the standard reception range of conventionalATIS via landline and data link communications tothe cockpit. Also, the service provides a computer−synthesized voice message that can be transmitted toall aircraft within range of existing transmitters. TheTerminal Data Link System (TDLS) D-ATISapplication uses weather inputs from local automatedweather sources or manually entered meteorologicaldata together with preprogrammed menus to providestandard information to users. Airports with D-ATIScapability are listed in the Chart Supplement U.S.

DIGITAL TARGET− A computer−generated symbolrepresenting an aircraft’s position, based on a primaryreturn or radar beacon reply, shown on a digitaldisplay.

DIGITAL TERMINAL AUTOMATION SYSTEM(DTAS)− A system where digital radar and beacondata is presented on digital displays and theoperational program monitors the system perfor-mance on a real−time basis.

DIGITIZED TARGET− A computer−generatedindication shown on an analog radar display resultingfrom a primary radar return or a radar beacon reply.


PCG D−3

DIRECT− Straight line flight between two naviga-tional aids, fixes, points, or any combination thereof.When used by pilots in describing off-airway routes,points defining direct route segments becomecompulsory reporting points unless the aircraft isunder radar contact.

DIRECTLY BEHIND− An aircraft is considered tobe operating directly behind when it is following theactual flight path of the lead aircraft over the surfaceof the earth except when applying wake turbulenceseparation criteria.

DISCRETE BEACON CODE−(See DISCRETE CODE.)

DISCRETE CODE− As used in the Air TrafficControl Radar Beacon System (ATCRBS), any oneof the 4096 selectable Mode 3/A aircraft transpondercodes except those ending in zero zero; e.g., discretecodes: 0010, 1201, 2317, 7777; nondiscrete codes:0100, 1200, 7700. Nondiscrete codes are normallyreserved for radar facilities that are not equipped withdiscrete decoding capability and for other purposessuch as emergencies (7700), VFR aircraft (1200), etc.

(See RADAR.)(Refer to AIM.)

DISCRETE FREQUENCY− A separate radiofrequency for use in direct pilot-controller commu-nications in air traffic control which reducesfrequency congestion by controlling the number ofaircraft operating on a particular frequency at onetime. Discrete frequencies are normally designatedfor each control sector in en route/terminal ATCfacilities. Discrete frequencies are listed in the ChartSupplement U.S. and the DOD FLIP IFR En RouteSupplement.

(See CONTROL SECTOR.)

DISPLACED THRESHOLD− A threshold that islocated at a point on the runway other than thedesignated beginning of the runway.

(See THRESHOLD.)(Refer to AIM.)

DISTANCE MEASURING EQUIPMENT (DME)−Equipment (airborne and ground) used to measure, innautical miles, the slant range distance of an aircraftfrom the DME navigational aid.

(See TACAN.)(See VORTAC.)

DISTRESS− A condition of being threatened byserious and/or imminent danger and of requiringimmediate assistance.

DIVE BRAKES−(See SPEED BRAKES.)

DIVERSE VECTOR AREA− In a radar environ-ment, that area in which a prescribed departure routeis not required as the only suitable route to avoidobstacles. The area in which random radar vectorsbelow the MVA/MIA, established in accordance withthe TERPS criteria for diverse departures, obstaclesand terrain avoidance, may be issued to departingaircraft.

DIVERSION (DVRSN)− Flights that are required toland at other than their original destination forreasons beyond the control of the pilot/company, e.g.periods of significant weather.

DME−(See DISTANCE MEASURING EQUIPMENT.)

DME FIX− A geographical position determined byreference to a navigational aid which providesdistance and azimuth information. It is defined by aspecific distance in nautical miles and a radial,azimuth, or course (i.e., localizer) in degreesmagnetic from that aid.

(See DISTANCE MEASURING EQUIPMENT.)(See FIX.)

DME SEPARATION− Spacing of aircraft in terms ofdistances (nautical miles) determined by reference todistance measuring equipment (DME).

(See DISTANCE MEASURING EQUIPMENT.)

DOD FLIP− Department of Defense Flight Informa-tion Publications used for flight planning, en route,and terminal operations. FLIP is produced by theNational Geospatial−Intelligence Agency (NGA) forworld-wide use. United States Government FlightInformation Publications (en route charts andinstrument approach procedure charts) are incorpo-rated in DOD FLIP for use in the National AirspaceSystem (NAS).

DOMESTIC AIRSPACE− Airspace which overliesthe continental land mass of the United States plusHawaii and U.S. possessions. Domestic airspaceextends to 12 miles offshore.

DOWNBURST− A strong downdraft which inducesan outburst of damaging winds on or near the ground.Damaging winds, either straight or curved, are highly


PCG D−4

divergent. The sizes of downbursts vary from 1/2mile or less to more than 10 miles. An intensedownburst often causes widespread damage. Damag-ing winds, lasting 5 to 30 minutes, could reach speedsas high as 120 knots.

DOWNWIND LEG−(See TRAFFIC PATTERN.)

DP−(See INSTRUMENT DEPARTURE PROCEDURE.)

DRAG CHUTE− A parachute device installed oncertain aircraft which is deployed on landing roll toassist in deceleration of the aircraft.

DROP ZONE− Any pre-determined area upon whichparachutists or objects land after making anintentional parachute jump or drop.

(Refer to 14 CFR §105.3, Definitions)

DSP−(See DEPARTURE SEQUENCING PROGRAM.)

DT−(See DELAY TIME.)

DTAS−(See DIGITAL TERMINAL AUTOMATIONSYSTEM.)

DUE REGARD− A phase of flight wherein anaircraft commander of a State-operated aircraft

assumes responsibility to separate his/her aircraftfrom all other aircraft.

(See also FAA Order JO 7110.65, Para 1−2−1,WORD MEANINGS.)

DUTY RUNWAY−(See RUNWAY IN USE/ACTIVE RUNWAY/DUTYRUNWAY.)

DVA−(See DIVERSE VECTOR AREA.)

DVFR−(See DEFENSE VISUAL FLIGHT RULES.)

DVFR FLIGHT PLAN− A flight plan filed for a VFRaircraft which intends to operate in airspace withinwhich the ready identification, location, and controlof aircraft are required in the interest of nationalsecurity.

DVRSN−(See DIVERSION.)

DYNAMIC− Continuous review, evaluation, andchange to meet demands.

DYNAMIC RESTRICTIONS− Those restrictionsimposed by the local facility on an “as needed” basisto manage unpredictable fluctuations in trafficdemands.


PCG E−1

EEAS−

(See EN ROUTE AUTOMATION SYSTEM.)

EDCT−(See EXPECT DEPARTURE CLEARANCETIME.)

EDST−(See EN ROUTE DECISION SUPPORT TOOL)

EFC−(See EXPECT FURTHER CLEARANCE (TIME).)

ELT−(See EMERGENCY LOCATOR TRANSMITTER.)

EMERGENCY− A distress or an urgency condition.

EMERGENCY LOCATOR TRANSMITTER(ELT)− A radio transmitter attached to the aircraftstructure which operates from its own power sourceon 121.5 MHz and 243.0 MHz. It aids in locatingdowned aircraft by radiating a downward sweepingaudio tone, 2-4 times per second. It is designed tofunction without human action after an accident.


E-MSAW−(See EN ROUTE MINIMUM SAFE ALTITUDEWARNING.)

ENHANCED FLIGHT VISION SYSTEM (EFVS)−An EFVS is an installed aircraft system which usesan electronic means to provide a display of theforward external scene topography (the natural orman−made features of a place or region especially ina way to show their relative positions and elevation)through the use of imaging sensors, including but notlimited to forward−looking infrared, millimeter waveradiometry, millimeter wave radar, or low−light levelimage intensification. An EFVS includes the displayelement, sensors, computers and power supplies,indications, and controls. An operator’s authoriza-tion to conduct an EFVS operation may haveprovisions which allow pilots to conduct IAPs whenthe reported weather is below minimums prescribedon the IAP to be flown.

EN ROUTE AIR TRAFFIC CONTROL SER-VICES− Air traffic control service provided aircrafton IFR flight plans, generally by centers, when these

aircraft are operating between departure anddestination terminal areas. When equipment, capa-bilities, and controller workload permit, certainadvisory/assistance services may be provided to VFRaircraft.


(Refer to AIM.)

EN ROUTE AUTOMATION SYSTEM (EAS)− Thecomplex integrated environment consisting ofsituation display systems, surveillance systems andflight data processing, remote devices, decisionsupport tools, and the related communicationsequipment that form the heart of the automated IFRair traffic control system. It interfaces with automatedterminal systems and is used in the control of en routeIFR aircraft.

(Refer to AIM.)

EN ROUTE CHARTS−(See AERONAUTICAL CHART.)

EN ROUTE DECISION SUPPORT TOOL (EDST)−An automated tool provided at each Radar Associateposition in selected En Route facilities. This toolutilizes flight and radar data to determine present andfuture trajectories for all active and proposal aircraftand provides enhanced automated flight datamanagement.

EN ROUTE DESCENT− Descent from the en routecruising altitude which takes place along the route offlight.

EN ROUTE HIGH ALTITUDE CHARTS−(See AERONAUTICAL CHART.)

EN ROUTE LOW ALTITUDE CHARTS−(See AERONAUTICAL CHART.)

EN ROUTE MINIMUM SAFE ALTITUDE WARN-ING (E−MSAW)− A function of the EAS that aids thecontroller by providing an alert when a trackedaircraft is below or predicted by the computer to gobelow a predetermined minimum IFR altitude(MIA).

EN ROUTE SPACING PROGRAM (ESP)− Aprogram designed to assist the exit sector inachieving the required in-trail spacing.


PCG E−2

EN ROUTE TRANSITION−

a. Conventional STARs/SIDs. The portion of aSID/STAR that connects to one or more en routeairway/jet route.

b. RNAV STARs/SIDs. The portion of a STARpreceding the common route or point, or for a SID theportion following, that is coded for a specific en routefix, airway or jet route.

ESP−(See EN ROUTE SPACING PROGRAM.)

EST−(See ESTIMATED.)

ESTABLISHED− To be stable or fixed at an altitudeor on a course, route, route segment, heading,instrument approach or departure procedure, etc.

ESTABLISHED ON RNP (EoR) CONCEPT– Asystem of authorized instrument approaches, ATCprocedures, surveillance, and communication re-quirements that allow aircraft operations to be safelyconducted with approved reduced separation criteriaonce aircraft are established on a PBN segment of apublished instrument flight procedure.

ESTIMATED (EST)−When used in NOTAMs“EST” is a contraction that is used by the issuingauthority only when the condition is expected toreturn to service prior to the expiration time. Using“EST” lets the user know that this NOTAM has thepossibility of returning to service earlier than theexpiration time. Any NOTAM which includes an“EST” will be auto−expired at the designatedexpiration time.

ESTIMATED ELAPSED TIME [ICAO]− Theestimated time required to proceed from onesignificant point to another.

(See ICAO Term TOTAL ESTIMATED ELAPSEDTIME.)

ESTIMATED OFF-BLOCK TIME [ICAO]− Theestimated time at which the aircraft will commencemovement associated with departure.

ESTIMATED POSITION ERROR (EPE)−(See Required Navigation Performance)

ESTIMATED TIME OF ARRIVAL− The time theflight is estimated to arrive at the gate (scheduledoperators) or the actual runway on times fornonscheduled operators.

ESTIMATED TIME EN ROUTE− The estimatedflying time from departure point to destination(lift-off to touchdown).

ETA−(See ESTIMATED TIME OF ARRIVAL.)

ETE−(See ESTIMATED TIME EN ROUTE.)

EXECUTE MISSED APPROACH− Instructionsissued to a pilot making an instrument approachwhich means continue inbound to the missedapproach point and execute the missed approachprocedure as described on the Instrument ApproachProcedure Chart or as previously assigned by ATC.The pilot may climb immediately to the altitudespecified in the missed approach procedure uponmaking a missed approach. No turns should beinitiated prior to reaching the missed approach point.When conducting an ASR or PAR approach, executethe assigned missed approach procedure immediatelyupon receiving instructions to “execute missedapproach.”

(Refer to AIM.)

EXPECT (ALTITUDE) AT (TIME) or (FIX)− Usedunder certain conditions to provide a pilot with analtitude to be used in the event of two-waycommunications failure. It also provides altitudeinformation to assist the pilot in planning.

(Refer to AIM.)

EXPECT DEPARTURE CLEARANCE TIME(EDCT)− The runway release time assigned to anaircraft in a traffic management program and shownon the flight progress strip as an EDCT.

(See GROUND DELAY PROGRAM.)

EXPECT FURTHER CLEARANCE (TIME)− Thetime a pilot can expect to receive clearance beyond aclearance limit.

EXPECT FURTHER CLEARANCE VIA (AIR-WAYS, ROUTES OR FIXES)− Used to inform apilot of the routing he/she can expect if any part of theroute beyond a short range clearance limit differsfrom that filed.

EXPEDITE− Used by ATC when prompt com-pliance is required to avoid the development of animminent situation. Expedite climb/descent normal-ly indicates to a pilot that the approximate best rateof climb/descent should be used without requiring anexceptional change in aircraft handling characteris-tics.


PCG F−1

FFAF−

(See FINAL APPROACH FIX.)

FALLEN HERO– Remains of fallen members of theUnited States military are often returned home byaircraft. These flights may be identified with thephrase “FALLEN HERO” added to the remarkssection of the flight plan, or they may be transmittedvia air/ground communications. If able, these flightswill receive priority handling.

FAST FILE− An FSS system whereby a pilot files aflight plan via telephone that is recorded and latertranscribed for transmission to the appropriate airtraffic facility. (Alaska only.)

FAWP− Final Approach Waypoint

FCLT−(See FREEZE CALCULATED LANDING TIME.)

FEATHERED PROPELLER− A propeller whoseblades have been rotated so that the leading andtrailing edges are nearly parallel with the aircraftflight path to stop or minimize drag and enginerotation. Normally used to indicate shutdown of areciprocating or turboprop engine due to malfunc-tion.

FEDERAL AIRWAYS−(See LOW ALTITUDE AIRWAY STRUCTURE.)

FEEDER FIX− The fix depicted on InstrumentApproach Procedure Charts which establishes thestarting point of the feeder route.

FEEDER ROUTE− A route depicted on instrumentapproach procedure charts to designate routes foraircraft to proceed from the en route structure to theinitial approach fix (IAF).

(See INSTRUMENT APPROACHPROCEDURE.)

FERRY FLIGHT− A flight for the purpose of:

a. Returning an aircraft to base.

b. Delivering an aircraft from one location toanother.

c. Moving an aircraft to and from a maintenancebase. Ferry flights, under certain conditions, may beconducted under terms of a special flight permit.

FIELD ELEVATION−(See AIRPORT ELEVATION.)

FILED− Normally used in conjunction with flightplans, meaning a flight plan has been submitted toATC.

FILED EN ROUTE DELAY− Any of the followingpreplanned delays at points/areas along the route offlight which require special flight plan filing andhandling techniques.

a. Terminal Area Delay. A delay within a terminalarea for touch-and-go, low approach, or otherterminal area activity.

b. Special Use Airspace Delay. A delay within aMilitary Operations Area, Restricted Area, WarningArea, or ATC Assigned Airspace.

c. Aerial Refueling Delay. A delay within anAerial Refueling Track or Anchor.

FILED FLIGHT PLAN− The flight plan as filed withan ATS unit by the pilot or his/her designatedrepresentative without any subsequent changes orclearances.

FINAL− Commonly used to mean that an aircraft ison the final approach course or is aligned with alanding area.

(See FINAL APPROACH COURSE.)(See FINAL APPROACH-IFR.)(See SEGMENTS OF AN INSTRUMENTAPPROACH PROCEDURE.)

FINAL APPROACH [ICAO]− That part of aninstrument approach procedure which commences atthe specified final approach fix or point, or wheresuch a fix or point is not specified.

a. At the end of the last procedure turn, base turnor inbound turn of a racetrack procedure, if specified;or

b. At the point of interception of the last trackspecified in the approach procedure; and ends at apoint in the vicinity of an aerodrome from which:

1. A landing can be made; or2. A missed approach procedure is initiated.

FINAL APPROACH COURSE− A bearing/radial/track of an instrument approach leading to a runwayor an extended runway centerline all without regardto distance.


PCG F−2

FINAL APPROACH FIX− The fix from which thefinal approach (IFR) to an airport is executed andwhich identifies the beginning of the final approachsegment. It is designated on Government charts bythe Maltese Cross symbol for nonprecisionapproaches and the lightning bolt symbol,designating the PFAF, for precision approaches; orwhen ATC directs a lower-than-publishedglideslope/path or vertical path intercept altitude, it isthe resultant actual point of the glideslope/path orvertical path intercept.

(See FINAL APPROACH POINT.)

(See GLIDESLOPE INTERCEPT ALTITUDE.)

(See SEGMENTS OF AN INSTRUMENTAPPROACH PROCEDURE.)

FINAL APPROACH-IFR− The flight path of anaircraft which is inbound to an airport on a finalinstrument approach course, beginning at the finalapproach fix or point and extending to the airport orthe point where a circle-to-land maneuver or a missedapproach is executed.

(See FINAL APPROACH COURSE.)


(See FINAL APPROACH POINT.)


(See ICAO term FINAL APPROACH.)

FINAL APPROACH POINT− The point, applicableonly to a nonprecision approach with no depictedFAF (such as an on airport VOR), where the aircraftis established inbound on the final approach coursefrom the procedure turn and where the final approachdescent may be commenced. The FAP serves as theFAF and identifies the beginning of the finalapproach segment.



FINAL APPROACH SEGMENT−


FINAL APPROACH SEGMENT [ICAO]− Thatsegment of an instrument approach procedure inwhich alignment and descent for landing areaccomplished.

FINAL CONTROLLER− The controller providinginformation and final approach guidance during PARand ASR approaches utilizing radar equipment.

(See RADAR APPROACH.)

FINAL GUARD SERVICE− A value added serviceprovided in conjunction with LAA/RAA only duringperiods of significant and fast changing weatherconditions that may affect landing and takeoffoperations.

FINAL MONITOR AID− A high resolution colordisplay that is equipped with the controller alertsystem hardware/software used to monitor the notransgression zone (NTZ) during simultaneousparallel approach operations. The display includesalert algorithms providing the target predictors, acolor change alert when a target penetrates or ispredicted to penetrate the no transgression zone(NTZ), synthesized voice alerts, and digital mapping.


FINAL MONITOR CONTROLLER− Air TrafficControl Specialist assigned to radar monitor theflight path of aircraft during simultaneous parallel(approach courses spaced less than 9000 feet/9200feet above 5000 feet) and simultaneous close parallelapproach operations. Each runway is assigned a finalmonitor controller during simultaneous parallel andsimultaneous close parallel ILS approaches.

FIR−(See FLIGHT INFORMATION REGION.)

FIRST TIER CENTER− An ARTCC immediatelyadjacent to the impacted center.

FIS−B−(See FLIGHT INFORMATIONSERVICE−BROADCAST.)

FIX− A geographical position determined by visualreference to the surface, by reference to one or moreradio NAVAIDs, by celestial plotting, or by anothernavigational device.

FIX BALANCING− A process whereby aircraft areevenly distributed over several available arrival fixesreducing delays and controller workload.

FLAG− A warning device incorporated in certainairborne navigation and flight instruments indicatingthat:

a. Instruments are inoperative or otherwise notoperating satisfactorily, or


PCG F−3

b. Signal strength or quality of the received signalfalls below acceptable values.

FLAG ALARM−(See FLAG.)

FLAMEOUT− An emergency condition caused by aloss of engine power.

FLAMEOUT PATTERN− An approach normallyconducted by a single-engine military aircraftexperiencing loss or anticipating loss of enginepower or control. The standard overhead approachstarts at a relatively high altitude over a runway(“high key”) followed by a continuous 180 degreeturn to a high, wide position (“low key”) followed bya continuous 180 degree turn final. The standardstraight-in pattern starts at a point that results in astraight-in approach with a high rate of descent to therunway. Flameout approaches terminate in the typeapproach requested by the pilot (normally fullstop).

FLIGHT CHECK− A call sign prefix used by FAAaircraft engaged in flight inspection/certification ofnavigational aids and flight procedures. The word“recorded” may be added as a suffix; e.g., “FlightCheck 320 recorded” to indicate that an automatedflight inspection is in progress in terminal areas.

(See FLIGHT INSPECTION.)(Refer to AIM.)

FLIGHT FOLLOWING−(See TRAFFIC ADVISORIES.)

FLIGHT INFORMATION REGION− An airspace ofdefined dimensions within which Flight InformationService and Alerting Service are provided.

a. Flight Information Service. A service providedfor the purpose of giving advice and informationuseful for the safe and efficient conduct of flights.

b. Alerting Service. A service provided to notifyappropriate organizations regarding aircraft in needof search and rescue aid and to assist suchorganizations as required.

FLIGHT INFORMATION SERVICE− A serviceprovided for the purpose of giving advice andinformation useful for the safe and efficient conductof flights.

FLIGHT INFORMATION SERVICE−BROADCAST (FIS−B)− A ground broadcast serviceprovided through the ADS−B Broadcast Services

network over the UAT data link that operates on 978MHz. The FIS−B system provides pilots and flightcrews of properly equipped aircraft with a cockpitdisplay of certain aviation weather and aeronauticalinformation.

FLIGHT INSPECTION− Inflight investigation andevaluation of a navigational aid to determine whetherit meets established tolerances.

(See FLIGHT CHECK.)(See NAVIGATIONAL AID.)

FLIGHT LEVEL− A level of constant atmosphericpressure related to a reference datum of 29.92 inchesof mercury. Each is stated in three digits that representhundreds of feet. For example, flight level (FL) 250represents a barometric altimeter indication of25,000 feet; FL 255, an indication of 25,500 feet.

(See ICAO term FLIGHT LEVEL.)

FLIGHT LEVEL [ICAO]− A surface of constantatmospheric pressure which is related to a specificpressure datum, 1013.2 hPa (1013.2 mb), and isseparated from other such surfaces by specificpressure intervals.

Note 1: A pressure type altimeter calibrated inaccordance with the standard atmosphere:a. When set to a QNH altimeter setting, willindicate altitude;b. When set to a QFE altimeter setting, willindicate height above the QFE reference datum;andc. When set to a pressure of 1013.2 hPa (1013.2 mb), may be used to indicate flight levels.

Note 2: The terms ‘height’ and ‘altitude,’ used inNote 1 above, indicate altimetric rather thangeometric heights and altitudes.

FLIGHT LINE− A term used to describe the precisemovement of a civil photogrammetric aircraft alonga predetermined course(s) at a predetermined altitudeduring the actual photographic run.

FLIGHT MANAGEMENT SYSTEMS− A comput-er system that uses a large data base to allow routesto be preprogrammed and fed into the system bymeans of a data loader. The system is constantlyupdated with respect to position accuracy byreference to conventional navigation aids. Thesophisticated program and its associated data baseensures that the most appropriate aids are automati-cally selected during the information update cycle.


PCG F−4

FLIGHT PATH− A line, course, or track along whichan aircraft is flying or intended to be flown.

(See COURSE.)(See TRACK.)

FLIGHT PLAN− Specified information relating tothe intended flight of an aircraft that is filed orally orin writing with an FSS or an ATC facility.

(See FAST FILE.)(See FILED.)(Refer to AIM.)

FLIGHT PLAN AREA (FPA)− The geographicalarea assigned to a flight service station (FSS) for thepurpose of establishing primary responsibility forservices that may include search and rescue for VFRaircraft, issuance of NOTAMs, pilot briefings,inflight services, broadcast services, emergencyservices, flight data processing, international opera-tions, and aviation weather services. Largeconsolidated FSS facilities may combine FPAs intolarger areas of responsibility (AOR).

(See FLIGHT SERVICE STATION.)(See TIE-IN FACILITY.)

FLIGHT RECORDER− A general term applied toany instrument or device that records informationabout the performance of an aircraft in flight or aboutconditions encountered in flight. Flight recordersmay make records of airspeed, outside airtemperature, vertical acceleration, engine RPM,manifold pressure, and other pertinent variables for agiven flight.

(See ICAO term FLIGHT RECORDER.)

FLIGHT RECORDER [ICAO]− Any type ofrecorder installed in the aircraft for the purpose ofcomplementing accident/incident investigation.

Note: See Annex 6 Part I, for specifications relatingto flight recorders.

FLIGHT SERVICE STATION (FSS)− An air trafficfacility which provides pilot briefings, flight planprocessing, en route flight advisories, search andrescue services, and assistance to lost aircraft andaircraft in emergency situations. FSS also relay ATCclearances, process Notices to Airmen, broadcastaviation weather and aeronautical information, andadvise Customs and Immigration of transborderflights. In Alaska, FSS provide Airport AdvisoryServices.

(See FLIGHT PLAN AREA.)(See TIE-IN FACILITY.)

FLIGHT STANDARDS DISTRICT OFFICE− AnFAA field office serving an assigned geographicalarea and staffed with Flight Standards personnel whoserve the aviation industry and the general public onmatters relating to the certification and operation ofair carrier and general aviation aircraft. Activitiesinclude general surveillance of operational safety,certification of airmen and aircraft, accidentprevention, investigation, enforcement, etc.

FLIGHT TERMINATION− The intentional anddeliberate process of terminating the flight of a UA inthe event of an unrecoverable lost link, loss ofcontrol, or other failure that compromises the safetyof flight.

FLIGHT TEST− A flight for the purpose of:

a. Investigating the operation/flight characteris-tics of an aircraft or aircraft component.

b. Evaluating an applicant for a pilot certificate orrating.

FLIGHT VISIBILITY−(See VISIBILITY.)

FLIP−(See DOD FLIP.)

FLY HEADING (DEGREES)− Informs the pilot ofthe heading he/she should fly. The pilot may have toturn to, or continue on, a specific compass directionin order to comply with the instructions. The pilot isexpected to turn in the shorter direction to the headingunless otherwise instructed by ATC.

FLY-BY WAYPOINT− A fly-by waypoint requiresthe use of turn anticipation to avoid overshoot of thenext flight segment.

FLY-OVER WAYPOINT− A fly-over waypointprecludes any turn until the waypoint is overflownand is followed by an intercept maneuver of the nextflight segment.

FLY VISUAL TO AIRPORT−(See PUBLISHED INSTRUMENT APPROACHPROCEDURE VISUAL SEGMENT.)

FMA−(See FINAL MONITOR AID.)

FMS−(See FLIGHT MANAGEMENT SYSTEM.)

FORMATION FLIGHT− More than one aircraftwhich, by prior arrangement between the pilots,operate as a single aircraft with regard to navigation


PCG F−5

and position reporting. Separation between aircraftwithin the formation is the responsibility of the flightleader and the pilots of the other aircraft in the flight.This includes transition periods when aircraft withinthe formation are maneuvering to attain separationfrom each other to effect individual control andduring join-up and breakaway.

a. A standard formation is one in which aproximity of no more than 1 mile laterally orlongitudinally and within 100 feet vertically from theflight leader is maintained by each wingman.

b. Nonstandard formations are those operatingunder any of the following conditions:

1. When the flight leader has requested and ATChas approved other than standard formationdimensions.

2. When operating within an authorized altitudereservation (ALTRV) or under the provisions of aletter of agreement.

3. When the operations are conducted inairspace specifically designed for a special activity.

(See ALTITUDE RESERVATION.)(Refer to 14 CFR Part 91.)

FRC−(See REQUEST FULL ROUTE CLEARANCE.)

FREEZE/FROZEN− Terms used in referring toarrivals which have been assigned ACLTs and to thelists in which they are displayed.

FREEZE CALCULATED LANDING TIME− Adynamic parameter number of minutes prior to themeter fix calculated time of arrival for each aircraftwhen the TCLT is frozen and becomes an ACLT (i.e.,the VTA is updated and consequently the TCLT ismodified as appropriate until FCLT minutes prior tometer fix calculated time of arrival, at which timeupdating is suspended and an ACLT and a frozenmeter fix crossing time (MFT) is assigned).

FREEZE HORIZON− The time or point at which anaircraft’s STA becomes fixed and no longer fluctuateswith each radar update. This setting ensures aconstant time for each aircraft, necessary for themetering controller to plan his/her delay technique.This setting can be either in distance from the meterfix or a prescribed flying time to the meter fix.

FREEZE SPEED PARAMETER− A speed adaptedfor each aircraft to determine fast and slow aircraft.

Fast aircraft freeze on parameter FCLT and slowaircraft freeze on parameter MLDI.

FRICTION MEASUREMENT− A measurement ofthe friction characteristics of the runway pavementsurface using continuous self-watering frictionmeasurement equipment in accordance with thespecifications, procedures and schedules containedin AC 150/5320−12, Measurement, Construction,and Maintenance of Skid Resistant Airport PavementSurfaces.

FSDO−(See FLIGHT STANDARDS DISTRICT OFFICE.)

FSPD−(See FREEZE SPEED PARAMETER.)

FSS−(See FLIGHT SERVICE STATION.)

FUEL DUMPING− Airborne release of usable fuel.This does not include the dropping of fuel tanks.

(See JETTISONING OF EXTERNAL STORES.)

FUEL REMAINING− A phrase used by either pilotsor controllers when relating to the fuel remaining onboard until actual fuel exhaustion. When transmittingsuch information in response to either a controllerquestion or pilot initiated cautionary advisory to airtraffic control, pilots will state the APPROXIMATENUMBER OF MINUTES the flight can continuewith the fuel remaining. All reserve fuel SHOULDBE INCLUDED in the time stated, as should anallowance for established fuel gauge system error.

FUEL SIPHONING− Unintentional release of fuelcaused by overflow, puncture, loose cap, etc.

FUEL VENTING−(See FUEL SIPHONING.)

FUSED TARGET-(See DIGITAL TARGET)

FUSION [STARS]- the combination of all availablesurveillance sources (airport surveillance radar[ASR], air route surveillance radar [ARSR], ADS-B,etc.) into the display of a single tracked target for airtraffic control separation services. FUSION is theequivalent of the current single-sensor radar display.FUSION performance is characteristic of asingle-sensor radar display system. Terminal areasuse mono-pulse secondary surveillance radar (ASR9, Mode S or ASR 11, MSSR).



PCG G−1

GGATE HOLD PROCEDURES− Procedures atselected airports to hold aircraft at the gate or otherground location whenever departure delays exceed orare anticipated to exceed 15 minutes. The sequencefor departure will be maintained in accordance withinitial call−up unless modified by flow controlrestrictions. Pilots should monitor the groundcontrol/clearance delivery frequency for enginestart/taxi advisories or new proposed start/taxi timeif the delay changes.

GCA−(See GROUND CONTROLLED APPROACH.)

GDP−(See GROUND DELAY PROGRAM.)

GENERAL AVIATION− That portion of civilaviation that does not include scheduled orunscheduled air carriers or commercial spaceoperations.

(See ICAO term GENERAL AVIATION.)

GENERAL AVIATION [ICAO]− All civil aviationoperations other than scheduled air services andnonscheduled air transport operations for remunera-tion or hire.

GEO MAP− The digitized map markings associatedwith the ASR-9 Radar System.

GLIDEPATH−(See GLIDESLOPE.)

GLIDEPATH [ICAO]− A descent profile determinedfor vertical guidance during a final approach.

GLIDEPATH INTERCEPT ALTITUDE−(See GLIDESLOPE INTERCEPT ALTITUDE.)

GLIDESLOPE− Provides vertical guidance foraircraft during approach and landing. The glideslope/glidepath is based on the following:

a. Electronic components emitting signals whichprovide vertical guidance by reference to airborneinstruments during instrument approaches such asILS; or,

b. Visual ground aids, such as VASI, whichprovide vertical guidance for a VFR approach or for

the visual portion of an instrument approach andlanding.

c. PAR. Used by ATC to inform an aircraft makinga PAR approach of its vertical position (elevation)relative to the descent profile.

(See ICAO term GLIDEPATH.)

GLIDESLOPE INTERCEPT ALTITUDE− Thepublished minimum altitude to intercept theglideslope in the intermediate segment of aninstrument approach. Government charts use thelightning bolt symbol to identify this intercept point.This intersection is called the Precise Final Approachfix (PFAF). ATC directs a higher altitude, theresultant intercept becomes the PFAF.

(See FINAL APPROACH FIX.)(See SEGMENTS OF AN INSTRUMENTAPPROACH PROCEDURE.)

GLOBAL NAVIGATION SATELLITE SYSTEM(GNSS)− GNSS refers collectively to the worldwidepositioning, navigation, and timing determinationcapability available from one or more satelliteconstellations. A GNSS constellation may beaugmented by ground stations and/or geostationarysatellites to improve integrity and position accuracy.

(See GROUND−BASED AUGMENTATIONSYSTEM.)

(See SATELLITE−BASED AUGMENTATIONSYSTEM.)

GLOBAL NAVIGATION SATELLITE SYSTEMMINIMUM EN ROUTE IFR ALTITUDE (GNSSMEA)− The minimum en route IFR altitude on apublished ATS route or route segment which assuresacceptable Global Navigation Satellite Systemreception and meets obstacle clearance requirements.(Refer to 14 CFR Part 91.)(Refer to 14 CFR Part 95.)

GLOBAL POSITIONING SYSTEM (GPS)− GPSrefers to the worldwide positioning, navigation andtiming determination capability available from theU.S. satellite constellation. The service provided byGPS for civil use is defined in the GPS StandardPositioning System Performance Standard. GPS iscomposed of space, control, and user elements.



PCG G−2

GNSS [ICAO]−(See GLOBAL NAVIGATION SATELLITESYSTEM.)

GNSS MEA−(See GLOBAL NAVIGATION SATELLITESYSTEM MINIMUM EN ROUTE IFRALTITUDE.)

GO AHEAD− Proceed with your message. Not to beused for any other purpose.

GO AROUND− Instructions for a pilot to abandonhis/her approach to landing. Additional instructionsmay follow. Unless otherwise advised by ATC, aVFR aircraft or an aircraft conducting visualapproach should overfly the runway while climbingto traffic pattern altitude and enter the traffic patternvia the crosswind leg. A pilot on an IFR flight planmaking an instrument approach should execute thepublished missed approach procedure or proceed asinstructed by ATC; e.g., “Go around” (additionalinstructions if required).

(See LOW APPROACH.)(See MISSED APPROACH.)

GPD−(See GRAPHIC PLAN DISPLAY.)

GPS−(See GLOBAL POSITIONING SYSTEM.)

GRAPHIC PLAN DISPLAY (GPD)− A viewavailable with EDST that provides a graphic displayof aircraft, traffic, and notification of predictedconflicts. Graphic routes for Current Plans and TrialPlans are displayed upon controller request.


GROSS NAVIGATION ERROR (GNE) − A lateraldeviation from a cleared track, normally in excess of25 Nautical Miles (NM). More stringent standards(for example, 10NM in some parts of the NorthAtlantic region) may be used in certain regions tosupport reductions in lateral separation.

GROUND BASED AUGMENTATION SYSTEM(GBAS)– A ground based GNSS station whichprovides local differential corrections, integrityparameters and approach data via VHF data broadcastto GNSS users to meet real-time performancerequirements for CAT I precision approaches. Theaircraft applies the broadcast data to improve theaccuracy and integrity of its GNSS signals and

computes the deviations to the selected approach. Asingle ground station can serve multiple runway endsup to an approximate radius of 23 NM.

GROUND BASED AUGMENTATION SYSTEM(GBAS) LANDING SYSTEM (GLS)- A type ofprecision IAP based on local augmentation of GNSSdata using a single GBAS station to transmit locallycorrected GNSS data, integrity parameters andapproach information. This improves the accuracy ofaircraft GNSS receivers’ signal in space, enabling thepilot to fly a precision approach with much greaterflexibility, reliability and complexity. The GLSprocedure is published on standard IAP charts,features the title GLS with the designated runway andminima as low as 200 feet DA. Future plans areexpected to support Cat II and CAT III operations.

GROUND CLUTTER− A pattern produced on theradar scope by ground returns which may degradeother radar returns in the affected area. The effect ofground clutter is minimized by the use of movingtarget indicator (MTI) circuits in the radar equipmentresulting in a radar presentation which displays onlytargets which are in motion.

(See CLUTTER.)

GROUND COMMUNICATION OUTLET (GCO)−An unstaffed, remotely controlled, ground/groundcommunications facility. Pilots at uncontrolledairports may contact ATC and FSS via VHF to atelephone connection to obtain an instrumentclearance or close a VFR or IFR flight plan. They mayalso get an updated weather briefing prior to takeoff.Pilots will use four “key clicks” on the VHF radio tocontact the appropriate ATC facility or six “keyclicks” to contact the FSS. The GCO system isintended to be used only on the ground.

GROUND CONTROLLED APPROACH− A radarapproach system operated from the ground by airtraffic control personnel transmitting instructions tothe pilot by radio. The approach may be conductedwith surveillance radar (ASR) only or with bothsurveillance and precision approach radar (PAR).Usage of the term “GCA” by pilots is discouragedexcept when referring to a GCA facility. Pilots shouldspecifically request a “PAR” approach when aprecision radar approach is desired or request an“ASR” or “surveillance” approach when a nonpreci-sion radar approach is desired.




PCG G−3

GROUND DELAY PROGRAM (GDP)− A trafficmanagement process administered by the ATCSCC,when aircraft are held on the ground. The purpose ofthe program is to support the TM mission and limitairborne holding. It is a flexible program and may beimplemented in various forms depending upon theneeds of the AT system. Ground delay programsprovide for equitable assignment of delays to allsystem users.

GROUND SPEED− The speed of an aircraft relativeto the surface of the earth.

GROUND STOP (GS)− The GS is a process that

requires aircraft that meet a specific criteria to remainon the ground. The criteria may be airport specific,airspace specific, or equipment specific; for example,all departures to San Francisco, or all departuresentering Yorktown sector, or all Category I and IIaircraft going to Charlotte. GSs normally occur withlittle or no warning.

GROUND VISIBILITY−(See VISIBILITY.)

GS−(See GROUND STOP.)



PCG H−1

HHAA−

(See HEIGHT ABOVE AIRPORT.)

HAL−(See HEIGHT ABOVE LANDING.)

HANDOFF− An action taken to transfer the radaridentification of an aircraft from one controller toanother if the aircraft will enter the receivingcontroller’s airspace and radio communications withthe aircraft will be transferred.

HAR−(See HIGH ALTITUDE REDESIGN.)

HAT−(See HEIGHT ABOVE TOUCHDOWN.)

HAVE NUMBERS− Used by pilots to inform ATCthat they have received runway, wind, and altimeterinformation only.

HAZARDOUS WEATHER INFORMATION−Summary of significant meteorological information(SIGMET/WS), convective significant meteorologi-cal information (convective SIGMET/WST), urgentpilot weather reports (urgent PIREP/UUA), centerweather advisories (CWA), airmen’s meteorologicalinformation (AIRMET/WA) and any other weathersuch as isolated thunderstorms that are rapidlydeveloping and increasing in intensity, or lowceilings and visibilities that are becoming wide-spread which is considered significant and are notincluded in a current hazardous weather advisory.

HEAVY (AIRCRAFT)−(See AIRCRAFT CLASSES.)

HEIGHT ABOVE AIRPORT (HAA)− The height ofthe Minimum Descent Altitude above the publishedairport elevation. This is published in conjunctionwith circling minimums.

(See MINIMUM DESCENT ALTITUDE.)

HEIGHT ABOVE LANDING (HAL)− The heightabove a designated helicopter landing area used forhelicopter instrument approach procedures.


HEIGHT ABOVE TOUCHDOWN (HAT)− Theheight of the Decision Height or Minimum DescentAltitude above the highest runway elevation in the

touchdown zone (first 3,000 feet of the runway). HATis published on instrument approach charts inconjunction with all straight-in minimums.

(See DECISION HEIGHT.)(See MINIMUM DESCENT ALTITUDE.)

HELICOPTER− A heavier-than-air aircraft sup-ported in flight chiefly by the reactions of the air onone or more power-driven rotors on substantiallyvertical axes.

HELIPAD− A small, designated area, usually with aprepared surface, on a heliport, airport, landing/take-off area, apron/ramp, or movement area used fortakeoff, landing, or parking of helicopters.

HELIPORT− An area of land, water, or structure usedor intended to be used for the landing and takeoff ofhelicopters and includes its buildings and facilities ifany.

HELIPORT REFERENCE POINT (HRP)− Thegeographic center of a heliport.

HERTZ− The standard radio equivalent of frequencyin cycles per second of an electromagnetic wave.Kilohertz (kHz) is a frequency of one thousand cyclesper second. Megahertz (MHz) is a frequency of onemillion cycles per second.

HF−(See HIGH FREQUENCY.)

HF COMMUNICATIONS−(See HIGH FREQUENCY COMMUNICATIONS.)

HIGH ALTITUDE REDESIGN (HAR)− A level ofnon−restrictive routing (NRR) service for aircraftthat have all waypoints associated with the HARprogram in their flight management systems orRNAV equipage.

HIGH FREQUENCY− The frequency band between3 and 30 MHz.

(See HIGH FREQUENCY COMMUNICATIONS.)

HIGH FREQUENCY COMMUNICATIONS− Highradio frequencies (HF) between 3 and 30 MHz usedfor air-to-ground voice communication in overseasoperations.

HIGH SPEED EXIT−(See HIGH SPEED TAXIWAY.)



PCG H−2

HIGH SPEED TAXIWAY− A long radius taxiwaydesigned and provided with lighting or marking todefine the path of aircraft, traveling at high speed (upto 60 knots), from the runway center to a point on thecenter of a taxiway. Also referred to as long radiusexit or turn-off taxiway. The high speed taxiway isdesigned to expedite aircraft turning off the runwayafter landing, thus reducing runway occupancy time.

HIGH SPEED TURNOFF−

(See HIGH SPEED TAXIWAY.)

HOLD FOR RELEASE− Used by ATC to delay anaircraft for traffic management reasons; i.e., weather,traffic volume, etc. Hold for release instructions(including departure delay information) are used toinform a pilot or a controller (either directly orthrough an authorized relay) that an IFR departureclearance is not valid until a release time or additionalinstructions have been received.

(See ICAO term HOLDING POINT.)

HOLD−IN−LIEU OF PROCEDURE TURN− Ahold−in−lieu of procedure turn shall be establishedover a final or intermediate fix when an approach canbe made from a properly aligned holding pattern. Thehold−in−lieu of procedure turn permits the pilot toalign with the final or intermediate segment of theapproach and/or descend in the holding pattern to analtitude that will permit a normal descent to the finalapproach fix altitude. The hold−in−lieu of procedureturn is a required maneuver (the same as a procedureturn) unless the aircraft is being radar vectored to thefinal approach course, when “NoPT” is shown on theapproach chart, or when the pilot requests or thecontroller advises the pilot to make a “straight−in”approach.

HOLD PROCEDURE− A predetermined maneuverwhich keeps aircraft within a specified airspace whileawaiting further clearance from air traffic control.Also used during ground operations to keep aircraftwithin a specified area or at a specified point whileawaiting further clearance from air traffic control.

(See HOLDING FIX.)

(Refer to AIM.)

HOLDING FIX− A specified fix identifiable to apilot by NAVAIDs or visual reference to the ground

used as a reference point in establishing andmaintaining the position of an aircraft while holding.

(See FIX.)(See VISUAL HOLDING.)(Refer to AIM.)

HOLDING POINT [ICAO]− A specified location,identified by visual or other means, in the vicinity ofwhich the position of an aircraft in flight ismaintained in accordance with air traffic controlclearances.

HOLDING PROCEDURE−(See HOLD PROCEDURE.)

HOLD-SHORT POINT− A point on the runwaybeyond which a landing aircraft with a LAHSOclearance is not authorized to proceed. This pointmay be located prior to an intersecting runway,taxiway, predetermined point, or approach/departureflight path.

HOLD-SHORT POSITION LIGHTS− Flashingin-pavement white lights located at specifiedhold-short points.

HOLD-SHORT POSITION MARKING− Thepainted runway marking located at the hold-shortpoint on all LAHSO runways.

HOLD-SHORT POSITION SIGNS− Red and whiteholding position signs located alongside thehold-short point.

HOMING− Flight toward a NAVAID, withoutcorrecting for wind, by adjusting the aircraft headingto maintain a relative bearing of zero degrees.

(See BEARING.)(See ICAO term HOMING.)

HOMING [ICAO]− The procedure of using thedirection-finding equipment of one radio station withthe emission of another radio station, where at leastone of the stations is mobile, and whereby the mobilestation proceeds continuously towards the otherstation.

HOVER CHECK− Used to describe when ahelicopter/VTOL aircraft requires a stabilized hoverto conduct a performance/power check prior to hovertaxi, air taxi, or takeoff. Altitude of the hover willvary based on the purpose of the check.

HOVER TAXI− Used to describe a helicopter/VTOLaircraft movement conducted above the surface andin ground effect at airspeeds less than approximately



PCG H−3

20 knots. The actual height may vary, and somehelicopters may require hover taxi above 25 feet AGLto reduce ground effect turbulence or provideclearance for cargo slingloads.

(See AIR TAXI.)(See HOVER CHECK.)(Refer to AIM.)

HOW DO YOU HEAR ME?− A question relating tothe quality of the transmission or to determine howwell the transmission is being received.

HZ−(See HERTZ.)



PCG I−1

II SAY AGAIN− The message will be repeated.

IAF−(See INITIAL APPROACH FIX.)

IAP−(See INSTRUMENT APPROACHPROCEDURE.)

IAWP− Initial Approach Waypoint

ICAO−(See ICAO Term INTERNATIONAL CIVILAVIATION ORGANIZATION.)

ICAO 3LD−(See ICAO Term ICAO Three−Letter Designator)

ICAO Three−Letter Designator (3LD)− An ICAO3LD is an exclusive designator that, when usedtogether with a flight number, becomes the aircraftcall sign and provides distinct aircraft identificationto air traffic control (ATC). ICAO approves 3LDs toenhance the safety and security of the air trafficsystem. An ICAO 3LD may be assigned to acompany, agency, or organization and is used insteadof the aircraft registration number for ATCoperational and security purposes. An ICAO 3LD isalso used for aircraft identification in the flight planand associated messages and can be used fordomestic and international flights. A telephonyassociated with an ICAO 3LD is used for radiocommunication.

ICING− The accumulation of airframe ice.

Types of icing are:

a. Rime Ice− Rough, milky, opaque ice formed bythe instantaneous freezing of small supercooledwater droplets.

b. Clear Ice− A glossy, clear, or translucent iceformed by the relatively slow freezing or largesupercooled water droplets.

c. Mixed− A mixture of clear ice and rime ice.

Intensity of icing:

a. Trace− Ice becomes perceptible. Rate ofaccumulation is slightly greater than the rate ofsublimation. Deicing/anti-icing equipment is notutilized unless encountered for an extended period oftime (over 1 hour).

b. Light− The rate of accumulation may create aproblem if flight is prolonged in this environment(over 1 hour). Occasional use of deicing/anti-icingequipment removes/prevents accumulation. It doesnot present a problem if the deicing/anti-icingequipment is used.

c. Moderate− The rate of accumulation is such thateven short encounters become potentially hazardousand use of deicing/anti-icing equipment or flightdiversion is necessary.

d. Severe− The rate of ice accumulation is suchthat ice protection systems fail to remove theaccumulation of ice, or ice accumulates in locationsnot normally prone to icing, such as areas aft ofprotected surfaces and any other areas identified bythe manufacturer. Immediate exit from the conditionis necessary.

Note:Severe icing is aircraft dependent, as are the othercategories of icing intensity. Severe icing mayoccur at any ice accumulation rate when the icingrate or ice accumulations exceed the tolerance ofthe aircraft.

IDENT− A request for a pilot to activate the aircrafttransponder identification feature. This will help thecontroller to confirm an aircraft identity or to identifyan aircraft.

(Refer to AIM.)

IDENT FEATURE− The special feature in the AirTraffic Control Radar Beacon System (ATCRBS)equipment. It is used to immediately distinguish onedisplayed beacon target from other beacon targets.

(See IDENT.)

IDENTIFICATION [ICAO]− The situation whichexists when the position indication of a particularaircraft is seen on a situation display and positivelyidentified.

IF−(See INTERMEDIATE FIX.)

IF NO TRANSMISSION RECEIVED FOR(TIME)− Used by ATC in radar approaches to prefixprocedures which should be followed by the pilot inevent of lost communications.

(See LOST COMMUNICATIONS.)

IFR−(See INSTRUMENT FLIGHT RULES.)



PCG I−2

IFR AIRCRAFT− An aircraft conducting flight inaccordance with instrument flight rules.

IFR CONDITIONS− Weather conditions below theminimum for flight under visual flight rules.

(See INSTRUMENT METEOROLOGICALCONDITIONS.)

IFR DEPARTURE PROCEDURE−(See IFR TAKEOFF MINIMUMS ANDDEPARTURE PROCEDURES.)

(Refer to AIM.)

IFR FLIGHT−(See IFR AIRCRAFT.)

IFR LANDING MINIMUMS−(See LANDING MINIMUMS.)

IFR MILITARY TRAINING ROUTES (IR)− Routesused by the Department of Defense and associatedReserve and Air Guard units for the purpose ofconducting low-altitude navigation and tacticaltraining in both IFR and VFR weather conditionsbelow 10,000 feet MSL at airspeeds in excess of 250knots IAS.

IFR TAKEOFF MINIMUMS AND DEPARTUREPROCEDURES− Title 14 Code of FederalRegulations Part 91, prescribes standard takeoff rulesfor certain civil users. At some airports, obstructionsor other factors require the establishment ofnonstandard takeoff minimums, departure proce-dures, or both to assist pilots in avoiding obstaclesduring climb to the minimum en route altitude. Thoseairports are listed in FAA/DOD Instrument ApproachProcedures (IAPs) Charts under a section entitled“IFR Takeoff Minimums and Departure Procedures.”The FAA/DOD IAP chart legend illustrates thesymbol used to alert the pilot to nonstandard takeoffminimums and departure procedures. When depart-ing IFR from such airports or from any airports wherethere are no departure procedures, DPs, or ATCfacilities available, pilots should advise ATC of anydeparture limitations. Controllers may query a pilotto determine acceptable departure directions, turns,or headings after takeoff. Pilots should be familiarwith the departure procedures and must assure thattheir aircraft can meet or exceed any specified climbgradients.

IF/IAWP− Intermediate Fix/Initial Approach Way-point. The waypoint where the final approach courseof a T approach meets the crossbar of the T. When

designated (in conjunction with a TAA) thiswaypoint will be used as an IAWP when approachingthe airport from certain directions, and as an IFWPwhen beginning the approach from another IAWP.

IFWP− Intermediate Fix Waypoint

ILS−(See INSTRUMENT LANDING SYSTEM.)

ILS CATEGORIES− 1. Category I. An ILS approachprocedure which provides for approach to a heightabove touchdown of not less than 200 feet and withrunway visual range of not less than 1,800 feet.−2. Special Authorization Category I. An ILSapproach procedure which provides for approach toa height above touchdown of not less than 150 feetand with runway visual range of not less than 1,400feet, HUD to DH. 3. Category II. An ILS approachprocedure which provides for approach to a heightabove touchdown of not less than 100 feet and withrunway visual range of not less than 1,200 feet (withautoland or HUD to touchdown and noted onauthorization, RVR 1,000 feet).− 4. SpecialAuthorization Category II with Reduced Lighting.An ILS approach procedure which provides forapproach to a height above touchdown of not lessthan 100 feet and with runway visual range of not lessthan 1,200 feet with autoland or HUD to touchdownand noted on authorization (no touchdown zone andcenterline lighting are required).− 5. Category III:

a. IIIA.−An ILS approach procedure whichprovides for approach without a decision heightminimum and with runway visual range of not lessthan 700 feet.

b. IIIB.−An ILS approach procedure whichprovides for approach without a decision heightminimum and with runway visual range of not lessthan 150 feet.

c. IIIC.−An ILS approach procedure whichprovides for approach without a decision heightminimum and without runway visual rangeminimum.

IM−(See INNER MARKER.)

IMC−(See INSTRUMENT METEOROLOGICALCONDITIONS.)

IMMEDIATELY− Used by ATC or pilots when suchaction compliance is required to avoid an imminentsituation.



PCG I−3

INCERFA (Uncertainty Phase) [ICAO]− A situationwherein uncertainty exists as to the safety of anaircraft and its occupants.

INCREASED SEPARATION REQUIRED (ISR)–Indicates the confidence level of the track requires5NM separation. 3NM separation, 1 1/2NMseparation, and target resolution cannot be used.

INCREASE SPEED TO (SPEED)−(See SPEED ADJUSTMENT.)

INERTIAL NAVIGATION SYSTEM (INS)− AnRNAV system which is a form of self-containednavigation.

(See Area Navigation/RNAV.)

INFLIGHT REFUELING−(See AERIAL REFUELING.)

INFLIGHT WEATHER ADVISORY−(See WEATHER ADVISORY.)

INFORMATION REQUEST (INREQ)− A requestoriginated by an FSS for information concerning anoverdue VFR aircraft.

INITIAL APPROACH FIX (IAF)− The fixesdepicted on instrument approach procedure chartsthat identify the beginning of the initial approachsegment(s).

(See FIX.)(See SEGMENTS OF AN INSTRUMENTAPPROACH PROCEDURE.)

INITIAL APPROACH SEGMENT−(See SEGMENTS OF AN INSTRUMENTAPPROACH PROCEDURE.)

INITIAL APPROACH SEGMENT [ICAO]− Thatsegment of an instrument approach procedurebetween the initial approach fix and the intermediateapproach fix or, where applicable, the final approachfix or point.

INLAND NAVIGATION FACILITY− A navigationaid on a North American Route at which the commonroute and/or the noncommon route begins or ends.

INNER MARKER− A marker beacon used with anILS (CAT II) precision approach located between themiddle marker and the end of the ILS runway,transmitting a radiation pattern keyed at six dots persecond and indicating to the pilot, both aurally andvisually, that he/she is at the designated decisionheight (DH), normally 100 feet above the touchdown

zone elevation, on the ILS CAT II approach. It alsomarks progress during a CAT III approach.

(See INSTRUMENT LANDING SYSTEM.)(Refer to AIM.)

INNER MARKER BEACON−(See INNER MARKER.)

INREQ−(See INFORMATION REQUEST.)

INS−(See INERTIAL NAVIGATION SYSTEM.)

INSTRUMENT APPROACH−(See INSTRUMENT APPROACHPROCEDURE.)

INSTRUMENT APPROACH OPERATIONS[ICAO]− An approach and landing using instrumentsfor navigation guidance based on an instrumentapproach procedure. There are two methods forexecuting instrument approach operations:

a. A two−dimensional (2D) instrument approachoperation, using lateral navigation guidance only;and

b. A three−dimensional (3D) instrument approachoperation, using both lateral and vertical navigationguidance.

Note: Lateral and vertical navigation guidancerefers to the guidance provided either by:a) a ground−based radio navigation aid; orb) computer−generated navigation data fromground−based, space−based, self−containednavigation aids or a combination of these.

(See ICAO term INSTRUMENT APPROACHPROCEDURE.)

INSTRUMENT APPROACH PROCEDURE− Aseries of predetermined maneuvers for the orderlytransfer of an aircraft under instrument flightconditions from the beginning of the initial approachto a landing or to a point from which a landing maybe made visually. It is prescribed and approved for aspecific airport by competent authority.



a. U.S. civil standard instrument approachprocedures are approved by the FAA as prescribedunder 14 CFR Part 97 and are available for publicuse.



PCG I−4

b. U.S. military standard instrument approachprocedures are approved and published by theDepartment of Defense.

c. Special instrument approach procedures areapproved by the FAA for individual operators but arenot published in 14 CFR Part 97 for public use.

(See ICAO term INSTRUMENT APPROACHPROCEDURE.)

INSTRUMENT APPROACH PROCEDURE[ICAO]− A series of predetermined maneuvers byreference to flight instruments with specifiedprotection from obstacles from the initial approachfix, or where applicable, from the beginning of adefined arrival route to a point from which a landingcan be completed and thereafter, if a landing is notcompleted, to a position at which holding or en routeobstacle clearance criteria apply.

(See ICAO term INSTRUMENT APPROACHOPERATIONS)

INSTRUMENT APPROACH PROCEDURECHARTS−

(See AERONAUTICAL CHART.)

INSTRUMENT DEPARTURE PROCEDURE(DP)− A preplanned instrument flight rule (IFR)departure procedure published for pilot use, ingraphic or textual format, that provides obstructionclearance from the terminal area to the appropriate enroute structure. There are two types of DP, ObstacleDeparture Procedure (ODP), printed either textuallyor graphically, and, Standard Instrument Departure(SID), which is always printed graphically.

(See IFR TAKEOFF MINIMUMS ANDDEPARTURE PROCEDURES.)

(See OBSTACLE DEPARTURE PROCEDURES.)

(See STANDARD INSTRUMENT DEPARTURES.)

(Refer to AIM.)

INSTRUMENT DEPARTURE PROCEDURE (DP)CHARTS−

(See AERONAUTICAL CHART.)

INSTRUMENT FLIGHT RULES (IFR)− Rulesgoverning the procedures for conducting instrument

flight. Also a term used by pilots and controllers toindicate type of flight plan.

(See INSTRUMENT METEOROLOGICALCONDITIONS.)

(See VISUAL FLIGHT RULES.)(See VISUAL METEOROLOGICALCONDITIONS.)

(See ICAO term INSTRUMENT FLIGHTRULES.)

(Refer to AIM.)

INSTRUMENT FLIGHT RULES [ICAO]− A set ofrules governing the conduct of flight underinstrument meteorological conditions.

INSTRUMENT LANDING SYSTEM (ILS)− Aprecision instrument approach system which normal-ly consists of the following electronic componentsand visual aids:

a. Localizer.(See LOCALIZER.)b. Glideslope.(See GLIDESLOPE.)c. Outer Marker.(See OUTER MARKER.)d. Middle Marker.(See MIDDLE MARKER.)e. Approach Lights.(See AIRPORT LIGHTING.)(Refer to 14 CFR Part 91.)(Refer to AIM.)

INSTRUMENT METEOROLOGICAL CONDI-TIONS (IMC)− Meteorological conditions expressedin terms of visibility, distance from cloud, and ceilingless than the minima specified for visual meteorolog-ical conditions.

(See INSTRUMENT FLIGHT RULES.)(See VISUAL FLIGHT RULES.)(See VISUAL METEOROLOGICALCONDITIONS.)

INSTRUMENT RUNWAY− A runway equippedwith electronic and visual navigation aids for whicha precision or nonprecision approach procedurehaving straight-in landing minimums has beenapproved.

(See ICAO term INSTRUMENT RUNWAY.)

INSTRUMENT RUNWAY [ICAO]− One of thefollowing types of runways intended for theoperation of aircraft using instrument approachprocedures:



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a. Nonprecision Approach Runway− An instru-ment runway served by visual aids and a nonvisualaid providing at least directional guidance adequatefor a straight-in approach.

b. Precision Approach Runway, Category I− Aninstrument runway served by ILS and visual aidsintended for operations down to 60 m (200 feet)decision height and down to an RVR of the order of800 m.

c. Precision Approach Runway, Category II− Aninstrument runway served by ILS and visual aidsintended for operations down to 30 m (100 feet)decision height and down to an RVR of the order of400 m.

d. Precision Approach Runway, Category III− Aninstrument runway served by ILS to and along thesurface of the runway and:

1. Intended for operations down to an RVR ofthe order of 200 m (no decision height beingapplicable) using visual aids during the final phase oflanding;

2. Intended for operations down to an RVR ofthe order of 50 m (no decision height beingapplicable) using visual aids for taxiing;

3. Intended for operations without reliance onvisual reference for landing or taxiing.

Note 1: See Annex 10 Volume I, Part I, Chapter 3,for related ILS specifications.

Note 2: Visual aids need not necessarily bematched to the scale of nonvisual aids provided.The criterion for the selection of visual aids is theconditions in which operations are intended to beconducted.

INTEGRITY− The ability of a system to providetimely warnings to users when the system should notbe used for navigation.

INTERMEDIATE APPROACH SEGMENT−(See SEGMENTS OF AN INSTRUMENTAPPROACH PROCEDURE.)

INTERMEDIATE APPROACH SEGMENT[ICAO]− That segment of an instrument approachprocedure between either the intermediate approachfix and the final approach fix or point, or between theend of a reversal, race track or dead reckoning trackprocedure and the final approach fix or point, asappropriate.

INTERMEDIATE FIX− The fix that identifies thebeginning of the intermediate approach segment of aninstrument approach procedure. The fix is notnormally identified on the instrument approach chartas an intermediate fix (IF).


INTERMEDIATE LANDING− On the rare occasionthat this option is requested, it should be approved.The departure center, however, must advise theATCSCC so that the appropriate delay is carried overand assigned at the intermediate airport. Anintermediate landing airport within the arrival centerwill not be accepted without coordination with andthe approval of the ATCSCC.

INTERNATIONAL AIRPORT− Relating to interna-tional flight, it means:

a. An airport of entry which has been designatedby the Secretary of Treasury or Commissioner ofCustoms as an international airport for customsservice.

b. A landing rights airport at which specificpermission to land must be obtained from customsauthorities in advance of contemplated use.

c. Airports designated under the Convention onInternational Civil Aviation as an airport for use byinternational commercial air transport and/or interna-tional general aviation.

(See ICAO term INTERNATIONAL AIRPORT.)(Refer to Chart Supplement U.S.)

INTERNATIONAL AIRPORT [ICAO]− Any airportdesignated by the Contracting State in whoseterritory it is situated as an airport of entry anddeparture for international air traffic, where theformalities incident to customs, immigration, publichealth, animal and plant quarantine and similarprocedures are carried out.

INTERNATIONAL CIVIL AVIATION ORGA-NIZATION [ICAO]− A specialized agency of theUnited Nations whose objective is to develop theprinciples and techniques of international airnavigation and to foster planning and development ofinternational civil air transport.

INTERROGATOR− The ground-based surveillanceradar beacon transmitter-receiver, which normallyscans in synchronism with a primary radar,transmitting discrete radio signals which repetitious-ly request all transponders on the mode being used to



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reply. The replies received are mixed with theprimary radar returns and displayed on the same planposition indicator (radar scope). Also, applied to theairborne element of the TACAN/DME system.

(See TRANSPONDER.)

(Refer to AIM.)

INTERSECTING RUNWAYS− Two or morerunways which cross or meet within their lengths.

(See INTERSECTION.)

INTERSECTION−

a. A point defined by any combination of courses,radials, or bearings of two or more navigational aids.

b. Used to describe the point where two runways,a runway and a taxiway, or two taxiways cross ormeet.

INTERSECTION DEPARTURE− A departure fromany runway intersection except the end of the runway.

(See INTERSECTION.)

INTERSECTION TAKEOFF−(See INTERSECTION DEPARTURE.)

IR−(See IFR MILITARY TRAINING ROUTES.)

IRREGULAR SURFACE− A surface that is open foruse but not per regulations.

ISR−(See INCREASED SEPARATION REQUIRED.)



PCG J−1

JJAMMING− Denotes emissions that do not mimicGlobal Navigation Satellite System (GNSS) signals(e.g., GPS and WAAS), but rather interfere with thecivil receiver’s ability to acquire and track GNSSsignals. Jamming can result in denial of GNSSnavigation, positioning, timing and aircraft depen-dent functions.

JET BLAST− The rapid air movement produced byexhaust from jet engines.

JET ROUTE− A route designed to serve aircraftoperations from 18,000 feet MSL up to and includingflight level 450. The routes are referred to as “J”routes with numbering to identify the designatedroute; e.g., J105.

(See Class A AIRSPACE.)(Refer to 14 CFR Part 71.)

JET STREAM− A migrating stream of high-speedwinds present at high altitudes.

JETTISONING OF EXTERNAL STORES− Air-borne release of external stores; e.g., tiptanks,ordnance.

(See FUEL DUMPING.)


JOINT USE RESTRICTED AREA−

(See RESTRICTED AREA.)

JUMP ZONE− The airspace directly associated witha Drop Zone. Vertical and horizontal limits may belocally defined.



PCG K−1

KKNOWN TRAFFIC− With respect to ATC clear-ances, means aircraft whose altitude, position, andintentions are known to ATC.


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LLAA−

(See LOCAL AIRPORT ADVISORY.)

LAAS−(See LOW ALTITUDE ALERT SYSTEM.)

LAHSO− An acronym for “Land and Hold ShortOperation.” These operations include landing andholding short of an intersecting runway, a taxiway, apredetermined point, or an approach/departureflightpath.

LAHSO-DRY− Land and hold short operations onrunways that are dry.

LAHSO-WET− Land and hold short operations onrunways that are wet (but not contaminated).

LAND AND HOLD SHORT OPERATIONS−Operations which include simultaneous takeoffs andlandings and/or simultaneous landings when alanding aircraft is able and is instructed by thecontroller to hold-short of the intersecting runway/taxiway or designated hold-short point. Pilots areexpected to promptly inform the controller if the holdshort clearance cannot be accepted.

(See PARALLEL RUNWAYS.)

(Refer to AIM.)

LAND−BASED AIR DEFENSE IDENTIFICA-TION ZONE (ADIZ)− An ADIZ over U.S.metropolitan areas, which is activated and deactivat-ed as needed, with dimensions, activation dates, andother relevant information disseminated via NO-TAM.

(See AIR DEFENSE IDENTIFICATION ZONE.)

LANDING AREA− Any locality either on land,water, or structures, including airports/heliports andintermediate landing fields, which is used, orintended to be used, for the landing and takeoff ofaircraft whether or not facilities are provided for theshelter, servicing, or for receiving or dischargingpassengers or cargo.

(See ICAO term LANDING AREA.)

LANDING AREA [ICAO]− That part of a movementarea intended for the landing or take-off of aircraft.

LANDING DIRECTION INDICATOR− A devicewhich visually indicates the direction in whichlandings and takeoffs should be made.

(See TETRAHEDRON.)(Refer to AIM.)

LANDING DISTANCE AVAILABLE (LDA)− Therunway length declared available and suitable for alanding airplane.

(See ICAO term LANDING DISTANCEAVAILABLE.)

LANDING DISTANCE AVAILABLE [ICAO]− Thelength of runway which is declared available andsuitable for the ground run of an aeroplane landing.

LANDING MINIMUMS− The minimum visibilityprescribed for landing a civil aircraft while using aninstrument approach procedure. The minimumapplies with other limitations set forth in 14 CFRPart 91 with respect to the Minimum DescentAltitude (MDA) or Decision Height (DH) prescribedin the instrument approach procedures as follows:

a. Straight-in landing minimums. A statement ofMDA and visibility, or DH and visibility, required fora straight-in landing on a specified runway, or

b. Circling minimums. A statement of MDA andvisibility required for the circle-to-land maneuver.

Note: Descent below the MDA or DH must meet theconditions stated in 14 CFR Section 91.175.

(See CIRCLE-TO-LAND MANEUVER.)(See DECISION HEIGHT.)(See INSTRUMENT APPROACHPROCEDURE.)

(See MINIMUM DESCENT ALTITUDE.)(See STRAIGHT-IN LANDING.)(See VISIBILITY.)(Refer to 14 CFR Part 91.)

LANDING ROLL− The distance from the point oftouchdown to the point where the aircraft can bebrought to a stop or exit the runway.

LANDING SEQUENCE− The order in whichaircraft are positioned for landing.

(See APPROACH SEQUENCE.)

LAST ASSIGNED ALTITUDE− The last altitude/flight level assigned by ATC and acknowledged bythe pilot.

(See MAINTAIN.)(Refer to 14 CFR Part 91.)


PCG L−2

LATERAL NAVIGATION (LNAV)– A function ofarea navigation (RNAV) equipment which calculates,displays, and provides lateral guidance to a profile orpath.

LATERAL SEPARATION− The lateral spacing ofaircraft at the same altitude by requiring operation ondifferent routes or in different geographical locations.

(See SEPARATION.)

LDA−(See LOCALIZER TYPE DIRECTIONAL AID.)(See LANDING DISTANCE AVAILABLE.)(See ICAO Term LANDING DISTANCEAVAILABLE.)

LF−(See LOW FREQUENCY.)

LIGHTED AIRPORT− An airport where runway andobstruction lighting is available.

(See AIRPORT LIGHTING.)(Refer to AIM.)

LIGHT GUN− A handheld directional light signalingdevice which emits a brilliant narrow beam of white,green, or red light as selected by the tower controller.The color and type of light transmitted can be used toapprove or disapprove anticipated pilot actions whereradio communication is not available. The light gunis used for controlling traffic operating in the vicinityof the airport and on the airport movement area.

(Refer to AIM.)

LIGHT-SPORT AIRCRAFT (LSA)− AnFAA-registered aircraft, other than a helicopter orpowered-lift, that meets certain weight andperformance. Principally it is a single−engine aircraftwith a maximum of two seats and weighing no morethan 1,430 pounds if intended for operation on water,or 1,320 pounds if not. It must be of simple design(fixed landing gear (except if intended for operationson water or a glider), piston powered,nonpressurized, with a fixed or ground adjustablepropeller). Performance is also limited to a maximumairspeed in level flight of not more than 120 knotscalibrated airspeed (CAS), have a maximumnever-exceed speed of not more than 120 knots CASfor a glider, and have a maximum stalling speed,without the use of lift-enhancing devices of not morethan 45 knots CAS. It may be certificated as eitherExperimental LSA or as a Special LSA aircraft. A

minimum of a sport pilot certificate is required tooperate light-sport aircraft.

(Refer to 14 CFR Part 1, §1.1.)

LINE UP AND WAIT (LUAW)− Used by ATC toinform a pilot to taxi onto the departure runway to lineup and wait. It is not authorization for takeoff. It isused when takeoff clearance cannot immediately beissued because of traffic or other reasons.

(See CLEARED FOR TAKEOFF.)

LOCAL AIRPORT ADVISORY (LAA)− A serviceavailable only in Alaska and provided by facilitiesthat are located on the landing airport, have a discreteground−to−air communication frequency or thetower frequency when the tower is closed, automatedweather reporting with voice broadcasting, and acontinuous ASOS/AWOS data display, other contin-uous direct reading instruments, or manualobservations available to the specialist.

(See AIRPORT ADVISORY AREA.)

LOCAL TRAFFIC− Aircraft operating in the trafficpattern or within sight of the tower, or aircraft knownto be departing or arriving from flight in local practiceareas, or aircraft executing practice instrumentapproaches at the airport.


LOCALIZER− The component of an ILS whichprovides course guidance to the runway.

(See INSTRUMENT LANDING SYSTEM.)(See ICAO term LOCALIZER COURSE.)(Refer to AIM.)

LOCALIZER COURSE [ICAO]− The locus ofpoints, in any given horizontal plane, at which theDDM (difference in depth of modulation) is zero.

LOCALIZER OFFSET− An angular offset of thelocalizer aligned within 3� of the runway alignment.

LOCALIZER TYPE DIRECTIONAL AID (LDA)−A localizer with an angular offset that exceeds 3� ofthe runway alignment, used for nonprecisioninstrument approaches with utility and accuracycomparable to a localizer, but which are not part of acomplete ILS.

(Refer to AIM.)

LOCALIZER TYPE DIRECTIONAL AID (LDA)PRECISION RUNWAY MONITOR (PRM)APPROACH− An approach, which includes aglideslope, used in conjunction with an ILS PRM,RNAV PRM or GLS PRM approach to an adjacentrunway to conduct Simultaneous Offset Instrument


PCG L−3

Approaches (SOIA) to parallel runways whosecenterlines are separated by less than 3,000 feet andat least 750 feet. NTZ monitoring is required toconduct these approaches.

(See SIMULTANEOUS OFFSET INSTRUMENTAPPROACH (SOIA).)

(Refer to AIM)

LOCALIZER USABLE DISTANCE− The maxi-mum distance from the localizer transmitter at aspecified altitude, as verified by flight inspection, atwhich reliable course information is continuouslyreceived.

(Refer to AIM.)

LOCATOR [ICAO]− An LM/MF NDB used as an aidto final approach.

Note: A locator usually has an average radius ofrated coverage of between 18.5 and 46.3 km (10and 25 NM).

LONG RANGE NAVIGATION−(See LORAN.)

LONGITUDINAL SEPARATION− The longitudi-nal spacing of aircraft at the same altitude by aminimum distance expressed in units of time ormiles.

(See SEPARATION.)(Refer to AIM.)

LORAN− An electronic navigational system bywhich hyperbolic lines of position are determined bymeasuring the difference in the time of reception ofsynchronized pulse signals from two fixed transmit-ters. Loran A operates in the 1750-1950 kHzfrequency band. Loran C and D operate in the100-110 kHz frequency band. In 2010, the U.S. CoastGuard terminated all U.S. LORAN-C transmissions.

(Refer to AIM.)

LOST COMMUNICATIONS− Loss of the ability tocommunicate by radio. Aircraft are sometimesreferred to as NORDO (No Radio). Standard pilotprocedures are specified in 14 CFR Part 91. Radarcontrollers issue procedures for pilots to follow in theevent of lost communications during a radar approachwhen weather reports indicate that an aircraft willlikely encounter IFR weather conditions during theapproach.


LOST LINK (LL)− An interruption or loss of thecontrol link, or when the pilot is unable to effectcontrol of the aircraft and, as a result, the UA willperform a predictable or planned maneuver. Loss ofcommand and control link between the ControlStation and the aircraft. There are two types of links:

a. An uplink which transmits command instruc-tions to the aircraft, and

b. A downlink which transmits the status of theaircraft and provides situational awareness to thepilot.

LOST LINK PROCEDURE− Preprogrammed orpredetermined mitigations to ensure the continuedsafe operation of the UA in the event of a lost link(LL). In the event positive link cannot be established,flight termination must be implemented.

LOW ALTITUDE AIRWAY STRUCTURE− Thenetwork of airways serving aircraft operations up tobut not including 18,000 feet MSL.

(See AIRWAY.)

(Refer to AIM.)

LOW ALTITUDE ALERT, CHECK YOUR ALTI-TUDE IMMEDIATELY−

(See SAFETY ALERT.)

LOW APPROACH− An approach over an airport orrunway following an instrument approach or a VFRapproach including the go-around maneuver wherethe pilot intentionally does not make contact with therunway.

(Refer to AIM.)

LOW FREQUENCY (LF)− The frequency bandbetween 30 and 300 kHz.

(Refer to AIM.)

LOCALIZER PERFOMRNACE WITH VERTI-CAL GUIDANCE (LPV)− A type of approach withvertical guidance (APV) based on WAAS, publishedon RNAV (GPS) approach charts. This proceduretakes advantage of the precise lateral guidanceavailable from WAAS. The minima is published as adecision altitude (DA).

LUAW−(See LINE UP AND WAIT.)


PCG M−1

MMAA−

(See MAXIMUM AUTHORIZED ALTITUDE.)

MACH NUMBER− The ratio of true airspeed to thespeed of sound; e.g., MACH .82, MACH 1.6.

(See AIRSPEED.)

MACH TECHNIQUE [ICAO]− Describes a controltechnique used by air traffic control whereby turbojetaircraft operating successively along suitable routesare cleared to maintain appropriate MACH numbersfor a relevant portion of the en route phase of flight.The principle objective is to achieve improvedutilization of the airspace and to ensure thatseparation between successive aircraft does notdecrease below the established minima.

MAHWP− Missed Approach Holding Waypoint

MAINTAIN−

a. Concerning altitude/flight level, the termmeans to remain at the altitude/flight level specified.The phrase “climb and” or “descend and” normallyprecedes “maintain” and the altitude assignment;e.g., “descend and maintain 5,000.”

b. Concerning other ATC instructions, the term isused in its literal sense; e.g., maintain VFR.

MAINTENANCE PLANNING FRICTIONLEVEL− The friction level specified inAC 150/5320-12, Measurement, Construction, andMaintenance of Skid Resistant Airport PavementSurfaces, which represents the friction value belowwhich the runway pavement surface remainsacceptable for any category or class of aircraftoperations but which is beginning to show signs ofdeterioration. This value will vary depending on theparticular friction measurement equipment used.

MAKE SHORT APPROACH− Used by ATC toinform a pilot to alter his/her traffic pattern so as tomake a short final approach.


MAN PORTABLE AIR DEFENSE SYSTEMS(MANPADS)− MANPADS are lightweight,shoulder−launched, missile systems used to bringdown aircraft and create mass casualties. Thepotential for MANPADS use against airborne aircraft

is real and requires familiarity with the subject.Terrorists choose MANPADS because the weaponsare low cost, highly mobile, require minimal set−uptime, and are easy to use and maintain. Although theweapons have limited range, and their accuracy isaffected by poor visibility and adverse weather, theycan be fired from anywhere on land or from boatswhere there is unrestricted visibility to the target.

MANDATORY ALTITUDE− An altitude depictedon an instrument Approach Procedure Chartrequiring the aircraft to maintain altitude at thedepicted value.

MANPADS−(See MAN PORTABLE AIR DEFENSESYSTEMS.)

MAP−(See MISSED APPROACH POINT.)

MARKER BEACON− An electronic navigationfacility transmitting a 75 MHz vertical fan orboneshaped radiation pattern. Marker beacons areidentified by their modulation frequency and keyingcode, and when received by compatible airborneequipment, indicate to the pilot, both aurally andvisually, that he/she is passing over the facility.

(See INNER MARKER.)(See MIDDLE MARKER.)(See OUTER MARKER.)(Refer to AIM.)

MARSA−(See MILITARY AUTHORITY ASSUMESRESPONSIBILITY FOR SEPARATION OFAIRCRAFT.)

MAWP− Missed Approach Waypoint

MAXIMUM AUTHORIZED ALTITUDE− A pub-lished altitude representing the maximum usablealtitude or flight level for an airspace structure orroute segment. It is the highest altitude on a Federalairway, jet route, area navigation low or high route,or other direct route for which an MEA is designatedin 14 CFR Part 95 at which adequate reception ofnavigation aid signals is assured.

MAYDAY− The international radiotelephony distresssignal. When repeated three times, it indicates


PCG M−2

imminent and grave danger and that immediateassistance is requested.

(See PAN-PAN.) (Refer to AIM.)

MCA−(See MINIMUM CROSSING ALTITUDE.)

MDA−(See MINIMUM DESCENT ALTITUDE.)

MEA−(See MINIMUM EN ROUTE IFR ALTITUDE.)

MEARTS−(See MICRO-EN ROUTE AUTOMATED RADARTRACKING SYSTEM.)

METEOROLOGICAL IMPACT STATEMENT−An unscheduled planning forecast describingconditions expected to begin within 4 to 12 hourswhich may impact the flow of air traffic in a specificcenter’s (ARTCC) area.

METER FIX ARC− A semicircle, equidistant froma meter fix, usually in low altitude relatively close tothe meter fix, used to help CTAS/ERAM calculate ameter time, and determine appropriate sector meterlist assignments for aircraft not on an establishedarrival route or assigned a meter fix.

METER FIX TIME/SLOT TIME (MFT)− Acalculated time to depart the meter fix in order tocross the vertex at the ACLT. This time reflectsdescent speed adjustment and any applicable timethat must be absorbed prior to crossing the meter fix.

METER LIST−(See ARRIVAL SECTOR ADVISORY LIST.)

METER LIST DISPLAY INTERVAL− A dynamicparameter which controls the number of minutesprior to the flight plan calculated time of arrival at themeter fix for each aircraft, at which time the TCLT isfrozen and becomes an ACLT; i.e., the VTA isupdated and consequently the TCLT modified asappropriate until frozen at which time updating issuspended and an ACLT is assigned. When frozen,the flight entry is inserted into the arrival sector’smeter list for display on the sector PVD/MDM.MLDI is used if filed true airspeed is less than orequal to freeze speed parameters (FSPD).

METERING− A method of time-regulating arrivaltraffic flow into a terminal area so as not to exceed apredetermined terminal acceptance rate.

METERING AIRPORTS− Airports adapted formetering and for which optimum flight paths aredefined. A maximum of 15 airports may be adapted.

METERING FIX− A fix along an established routefrom over which aircraft will be metered prior toentering terminal airspace. Normally, this fix shouldbe established at a distance from the airport whichwill facilitate a profile descent 10,000 feet aboveairport elevation (AAE) or above.

METERING POSITION(S)− Adapted PVDs/MDMs and associated “D” positions eligible fordisplay of a metering position list. A maximum offour PVDs/MDMs may be adapted.

METERING POSITION LIST− An ordered list ofdata on arrivals for a selected metering airportdisplayed on a metering position PVD/MDM.

MFT−(See METER FIX TIME/SLOT TIME.)

MHA−(See MINIMUM HOLDING ALTITUDE.)

MIA−(See MINIMUM IFR ALTITUDES.)

MICROBURST− A small downburst with outburstsof damaging winds extending 2.5 miles or less. Inspite of its small horizontal scale, an intensemicroburst could induce wind speeds as high as 150knots

(Refer to AIM.)

MICRO-EN ROUTE AUTOMATED RADARTRACKING SYSTEM (MEARTS)− An automatedradar and radar beacon tracking system capable ofemploying both short-range (ASR) and long-range(ARSR) radars. This microcomputer driven systemprovides improved tracking, continuous data record-ing, and use of full digital radar displays.

MID RVR−(See VISIBILITY.)

MIDDLE COMPASS LOCATOR−(See COMPASS LOCATOR.)

MIDDLE MARKER− A marker beacon that definesa point along the glideslope of an ILS normallylocated at or near the point of decision height (ILSCategory I). It is keyed to transmit alternate dots anddashes, with the alternate dots and dashes keyed at therate of 95 dot/dash combinations per minute on a


PCG M−3

1300 Hz tone, which is received aurally and visuallyby compatible airborne equipment.

(See INSTRUMENT LANDING SYSTEM.)(See MARKER BEACON.)(Refer to AIM.)

MILES-IN-TRAIL− A specified distance betweenaircraft, normally, in the same stratum associatedwith the same destination or route of flight.

MILITARY AUTHORITY ASSUMES RESPONSI-BILITY FOR SEPARATION OF AIRCRAFT(MARSA)− A condition whereby the militaryservices involved assume responsibility for separa-tion between participating military aircraft in theATC system. It is used only for required IFRoperations which are specified in letters of agreementor other appropriate FAA or military documents.

MILITARY LANDING ZONE− A landing strip usedexclusively by the military for training. A militarylanding zone does not carry a runway designation.

MILITARY OPERATIONS AREA−(See SPECIAL USE AIRSPACE.)

MILITARY TRAINING ROUTES− Airspace ofdefined vertical and lateral dimensions establishedfor the conduct of military flight training at airspeedsin excess of 250 knots IAS.

(See IFR MILITARY TRAINING ROUTES.)(See VFR MILITARY TRAINING ROUTES.)

MINIMA−(See MINIMUMS.)

MINIMUM CROSSING ALTITUDE (MCA)− Thelowest altitude at certain fixes at which an aircraftmust cross when proceeding in the direction of ahigher minimum en route IFR altitude (MEA).

(See MINIMUM EN ROUTE IFR ALTITUDE.)

MINIMUM DESCENT ALTITUDE (MDA)− Thelowest altitude, expressed in feet above mean sealevel, to which descent is authorized on finalapproach or during circle-to-land maneuvering inexecution of a standard instrument approachprocedure where no electronic glideslope is provided.

(See NONPRECISION APPROACHPROCEDURE.)

MINIMUM EN ROUTE IFR ALTITUDE (MEA)−The lowest published altitude between radio fixes

which assures acceptable navigational signal cover-age and meets obstacle clearance requirementsbetween those fixes. The MEA prescribed for aFederal airway or segment thereof, area navigationlow or high route, or other direct route applies to theentire width of the airway, segment, or route betweenthe radio fixes defining the airway, segment, or route.



(Refer to AIM.)

MINIMUM FRICTION LEVEL− The friction levelspecified in AC 150/5320-12, Measurement, Con-struction, and Maintenance of Skid Resistant AirportPavement Surfaces, that represents the minimumrecommended wet pavement surface friction valuefor any turbojet aircraft engaged in LAHSO. Thisvalue will vary with the particular frictionmeasurement equipment used.

MINIMUM FUEL− Indicates that an aircraft’s fuelsupply has reached a state where, upon reaching thedestination, it can accept little or no delay. This is notan emergency situation but merely indicates anemergency situation is possible should any unduedelay occur.

(Refer to AIM.)

MINIMUM HOLDING ALTITUDE− The lowestaltitude prescribed for a holding pattern whichassures navigational signal coverage, communica-tions, and meets obstacle clearance requirements.

MINIMUM IFR ALTITUDES (MIA)− Minimumaltitudes for IFR operations as prescribed in 14 CFRPart 91. These altitudes are published on aeronauticalcharts and prescribed in 14 CFR Part 95 for airwaysand routes, and in 14 CFR Part 97 for standardinstrument approach procedures. If no applicableminimum altitude is prescribed in 14 CFR Part 95 or14 CFR Part 97, the following minimum IFRaltitude applies:

a. In designated mountainous areas, 2,000 feetabove the highest obstacle within a horizontaldistance of 4 nautical miles from the course to beflown; or

b. Other than mountainous areas, 1,000 feet abovethe highest obstacle within a horizontal distance of 4nautical miles from the course to be flown; or


PCG M−4

c. As otherwise authorized by the Administratoror assigned by ATC.

(See MINIMUM CROSSING ALTITUDE.)(See MINIMUM EN ROUTE IFR ALTITUDE.)(See MINIMUM OBSTRUCTION CLEARANCEALTITUDE.)

(See MINIMUM SAFE ALTITUDE.)(See MINIMUM VECTORING ALTITUDE.)(Refer to 14 CFR Part 91.)

MINIMUM OBSTRUCTION CLEARANCE ALTI-TUDE (MOCA)− The lowest published altitude ineffect between radio fixes on VOR airways,off-airway routes, or route segments which meetsobstacle clearance requirements for the entire routesegment and which assures acceptable navigationalsignal coverage only within 25 statute (22 nautical)miles of a VOR.

(Refer to 14 CFR Part 91.)(Refer to 14 CFR Part 95.)

MINIMUM RECEPTION ALTITUDE (MRA)− Thelowest altitude at which an intersection can bedetermined.


MINIMUM SAFE ALTITUDE (MSA)−

a. The minimum altitude specified in 14 CFRPart 91 for various aircraft operations.

b. Altitudes depicted on approach charts whichprovide at least 1,000 feet of obstacle clearance foremergency use. These altitudes will be identified asMinimum Safe Altitudes or Emergency SafeAltitudes and are established as follows:

1. Minimum Safe Altitude (MSA). Altitudesdepicted on approach charts which provide at least1,000 feet of obstacle clearance within a 25-mileradius of the navigation facility, waypoint, or airportreference point upon which the MSA is predicated.MSAs are for emergency use only and do notnecessarily assure acceptable navigational signalcoverage.

(See ICAO term Minimum Sector Altitude.)

2. Emergency Safe Altitude (ESA). Altitudesdepicted on approach charts which provide at least1,000 feet of obstacle clearance in nonmountainousareas and 2,000 feet of obstacle clearance indesignated mountainous areas within a 100-mileradius of the navigation facility or waypoint used asthe ESA center. These altitudes are normally usedonly in military procedures and are identified on

published procedures as “Emergency SafeAltitudes.”

MINIMUM SAFE ALTITUDE WARNING(MSAW)− A function of the ARTS III computer thataids the controller by alerting him/her when a trackedMode C equipped aircraft is below or is predicted bythe computer to go below a predetermined minimumsafe altitude.

(Refer to AIM.)

MINIMUM SECTOR ALTITUDE [ICAO]− Thelowest altitude which may be used under emergencyconditions which will provide a minimum clearanceof 300 m (1,000 feet) above all obstacles located inan area contained within a sector of a circle of 46 km(25 NM) radius centered on a radio aid to navigation.

MINIMUMS− Weather condition requirementsestablished for a particular operation or type ofoperation; e.g., IFR takeoff or landing, alternateairport for IFR flight plans, VFR flight, etc.

(See IFR CONDITIONS.)(See IFR TAKEOFF MINIMUMS ANDDEPARTURE PROCEDURES.)

(See LANDING MINIMUMS.)(See VFR CONDITIONS.)(Refer to 14 CFR Part 91.)(Refer to AIM.)

MINIMUM VECTORING ALTITUDE (MVA)−The lowest MSL altitude at which an IFR aircraft willbe vectored by a radar controller, except as otherwiseauthorized for radar approaches, departures, andmissed approaches. The altitude meets IFR obstacleclearance criteria. It may be lower than the publishedMEA along an airway or J-route segment. It may beutilized for radar vectoring only upon the controller’sdetermination that an adequate radar return is beingreceived from the aircraft being controlled. Chartsdepicting minimum vectoring altitudes are normallyavailable only to the controllers and not to pilots.

(Refer to AIM.)

MINUTES-IN-TRAIL− A specified interval be-tween aircraft expressed in time. This method wouldmore likely be utilized regardless of altitude.

MIS−(See METEOROLOGICAL IMPACTSTATEMENT.)

MISSED APPROACH−a. A maneuver conducted by a pilot when an

instrument approach cannot be completed to a


PCG M−5

landing. The route of flight and altitude are shown oninstrument approach procedure charts. A pilotexecuting a missed approach prior to the MissedApproach Point (MAP) must continue along the finalapproach to the MAP.

b. A term used by the pilot to inform ATC thathe/she is executing the missed approach.

c. At locations where ATC radar service isprovided, the pilot should conform to radar vectorswhen provided by ATC in lieu of the publishedmissed approach procedure.

(See MISSED APPROACH POINT.)

(Refer to AIM.)

MISSED APPROACH POINT (MAP)− A pointprescribed in each instrument approach procedure atwhich a missed approach procedure shall be executedif the required visual reference does not exist.

(See MISSED APPROACH.)


MISSED APPROACH PROCEDURE [ICAO]− Theprocedure to be followed if the approach cannot becontinued.

MISSED APPROACH SEGMENT−


MLDI−

(See METER LIST DISPLAY INTERVAL.)

MM−

(See MIDDLE MARKER.)

MOA−

(See MILITARY OPERATIONS AREA.)

MOCA−

(See MINIMUM OBSTRUCTION CLEARANCEALTITUDE.)

MODE− The letter or number assigned to a specificpulse spacing of radio signals transmitted or receivedby ground interrogator or airborne transpondercomponents of the Air Traffic Control Radar BeaconSystem (ATCRBS). Mode A (military Mode 3) and

Mode C (altitude reporting) are used in air trafficcontrol.

(See INTERROGATOR.)(See RADAR.)(See TRANSPONDER.)(See ICAO term MODE.)(Refer to AIM.)

MODE (SSR MODE) [ICAO]− The letter or numberassigned to a specific pulse spacing of theinterrogation signals transmitted by an interrogator.There are 4 modes, A, B, C and D specified in Annex10, corresponding to four different interrogationpulse spacings.

MODE C INTRUDER ALERT− A function ofcertain air traffic control automated systems designedto alert radar controllers to existing or pendingsituations between a tracked target (known IFR orVFR aircraft) and an untracked target (unknown IFRor VFR aircraft) that requires immediate attention/ac-tion.

(See CONFLICT ALERT.)

MODEL AIRCRAFT− An unmanned aircraft that is:(1) capable of sustained flight in the atmosphere; (2)flown within visual line of sight of the personoperating the aircraft; and (3) flown for hobby orrecreational purposes.

MONITOR− (When used with communicationtransfer) listen on a specific frequency and stand byfor instructions. Under normal circumstances do notestablish communications.

MONITOR ALERT (MA)− A function of the TFMSthat provides traffic management personnel with atool for predicting potential capacity problems inindividual operational sectors. The MA is anindication that traffic management personnel need toanalyze a particular sector for actual activity and todetermine the required action(s), if any, needed tocontrol the demand.

MONITOR ALERT PARAMETER (MAP)− Thenumber designated for use in monitor alertprocessing by the TFMS. The MAP is designated foreach operational sector for increments of 15 minutes.

MOSAIC/MULTI−SENSOR MODE− Accepts posi-tional data from multiple radar or ADS−B sites.Targets are displayed from a single source within aradar sort box according to the hierarchy of thesources assigned.

MOUNTAIN WAVE– Mountain waves occur whenair is being blown over a mountain range or even the


PCG M−6

ridge of a sharp bluff area. As the air hits the upwindside of the range, it starts to climb, thus creating whatis generally a smooth updraft which turns into aturbulent downdraft as the air passes the crest of theridge. Mountain waves can cause significantfluctuations in airspeed and altitude with or withoutassociated turbulence.

(Refer to AIM.)

MOVEMENT AREA− The runways, taxiways, andother areas of an airport/heliport which are utilizedfor taxiing/hover taxiing, air taxiing, takeoff, andlanding of aircraft, exclusive of loading ramps andparking areas. At those airports/heliports with atower, specific approval for entry onto the movementarea must be obtained from ATC.

(See ICAO term MOVEMENT AREA.)

MOVEMENT AREA [ICAO]− That part of anaerodrome to be used for the takeoff, landing andtaxiing of aircraft, consisting of the maneuvering areaand the apron(s).

MOVING TARGET INDICATOR− An electronicdevice which will permit radar scope presentationonly from targets which are in motion. A partialremedy for ground clutter.

MRA−(See MINIMUM RECEPTION ALTITUDE.)

MSA−(See MINIMUM SAFE ALTITUDE.)

MSAW−(See MINIMUM SAFE ALTITUDE WARNING.)

MTI−(See MOVING TARGET INDICATOR.)

MTR−(See MILITARY TRAINING ROUTES.)

MULTICOM− A mobile service not open to publiccorrespondence used to provide communicationsessential to conduct the activities being performed byor directed from private aircraft.

MULTIPLE RUNWAYS− The utilization of adedicated arrival runway(s) for departures and adedicated departure runway(s) for arrivals whenfeasible to reduce delays and enhance capacity.

MVA−(See MINIMUM VECTORING ALTITUDE.)


PCG N−1

NNAS−

(See NATIONAL AIRSPACE SYSTEM.)

NAT HLA–(See NORTH ATLANTIC HIGH LEVELAIRSPACE.)

NATIONAL AIRSPACE SYSTEM− The commonnetwork of U.S. airspace; air navigation facilities,equipment and services, airports or landing areas;aeronautical charts, information and services; rules,regulations and procedures, technical information,and manpower and material. Included are systemcomponents shared jointly with the military.

NATIONAL BEACON CODE ALLOCATIONPLAN AIRSPACE (NBCAP)− Airspace over UnitedStates territory located within the North Americancontinent between Canada and Mexico, includingadjacent territorial waters outward to about bound-aries of oceanic control areas (CTA)/FlightInformation Regions (FIR).

(See FLIGHT INFORMATION REGION.)

NATIONAL FLIGHT DATA CENTER (NFDC)− Afacility in Washington D.C., established by FAA tooperate a central aeronautical information service forthe collection, validation, and dissemination ofaeronautical data in support of the activities ofgovernment, industry, and the aviation community.The information is published in the National FlightData Digest.

(See NATIONAL FLIGHT DATA DIGEST.)

NATIONAL FLIGHT DATA DIGEST (NFDD)− Adaily (except weekends and Federal holidays)publication of flight information appropriate toaeronautical charts, aeronautical publications, No-tices to Airmen, or other media serving the purposeof providing operational flight data essential to safeand efficient aircraft operations.

NATIONAL SEARCH AND RESCUE PLAN− Aninteragency agreement which provides for theeffective utilization of all available facilities in alltypes of search and rescue missions.

NAVAID−(See NAVIGATIONAL AID.)

NAVAID CLASSES− VOR, VORTAC, and TACANaids are classed according to their operational use.The three classes of NAVAIDs are:

a. T− Terminal.

b. L− Low altitude.

c. H− High altitude.Note: The normal service range for T, L, and H classaids is found in the AIM. Certain operationalrequirements make it necessary to use some ofthese aids at greater service ranges thanspecified. Extended range is made possiblethrough flight inspection determinations. Someaids also have lesser service range due to location,terrain, frequency protection, etc. Restrictions toservice range are listed in Chart Supplement U.S.

NAVIGABLE AIRSPACE− Airspace at and abovethe minimum flight altitudes prescribed in the CFRsincluding airspace needed for safe takeoff andlanding.


NAVIGATION REFERENCE SYSTEM (NRS)−The NRS is a system of waypoints developed for usewithin the United States for flight planning andnavigation without reference to ground basednavigational aids. The NRS waypoints are located ina grid pattern along defined latitude and longitudelines. The initial use of the NRS will be in the highaltitude environment in conjunction with the HighAltitude Redesign initiative. The NRS waypoints areintended for use by aircraft capable of point−to−pointnavigation.

NAVIGATION SPECIFICATION [ICAO]− A set ofaircraft and flight crew requirements needed tosupport performance−based navigation operationswithin a defined airspace. There are two kinds ofnavigation specifications:

a. RNP specification. A navigation specificationbased on area navigation that includes therequirement for performance monitoring andalerting, designated by the prefix RNP; e.g., RNP 4,RNP APCH.

b. RNAV specification. A navigation specifica-tion based on area navigation that does not include therequirement for performance monitoring and alert-


PCG N−2

ing, designated by the prefix RNAV; e.g., RNAV 5,RNAV 1.

Note: The Performance−based Navigation Manual(Doc 9613), Volume II contains detailed guidanceon navigation specifications.

NAVIGATIONAL AID− Any visual or electronicdevice airborne or on the surface which providespoint-to-point guidance information or position datato aircraft in flight.

(See AIR NAVIGATION FACILITY.)

NAVSPEC-

(See NAVIGATION SPECIFICATION [ICAO].)

NBCAP AIRSPACE−(See NATIONAL BEACON CODE ALLOCATIONPLAN AIRSPACE.)

NDB−(See NONDIRECTIONAL BEACON.)

NEGATIVE− “No,” or “permission not granted,” or“that is not correct.”

NEGATIVE CONTACT− Used by pilots to informATC that:

a. Previously issued traffic is not in sight. It maybe followed by the pilot’s request for the controller toprovide assistance in avoiding the traffic.

b. They were unable to contact ATC on aparticular frequency.

NFDC−(See NATIONAL FLIGHT DATA CENTER.)

NFDD−(See NATIONAL FLIGHT DATA DIGEST.)

NIGHT− The time between the end of evening civiltwilight and the beginning of morning civil twilight,as published in the Air Almanac, converted to localtime.

(See ICAO term NIGHT.)

NIGHT [ICAO]− The hours between the end ofevening civil twilight and the beginning of morningcivil twilight or such other period between sunset andsunrise as may be specified by the appropriateauthority.

Note: Civil twilight ends in the evening when thecenter of the sun’s disk is 6 degrees below thehorizon and begins in the morning when the centerof the sun’s disk is 6 degrees below the horizon.

NO GYRO APPROACH− A radar approach/vectorprovided in case of a malfunctioning gyro-compassor directional gyro. Instead of providing the pilotwith headings to be flown, the controller observes theradar track and issues control instructions “turnright/left” or “stop turn” as appropriate.

(Refer to AIM.)

NO GYRO VECTOR−(See NO GYRO APPROACH.)

NO TRANSGRESSION ZONE (NTZ)− The NTZ isa 2,000 foot wide zone, located equidistant betweenparallel runway or SOIA final approach courses, inwhich flight is normally not allowed.

NONAPPROACH CONTROL TOWER− Author-izes aircraft to land or takeoff at the airport controlledby the tower or to transit the Class D airspace. Theprimary function of a nonapproach control tower isthe sequencing of aircraft in the traffic pattern and onthe landing area. Nonapproach control towers alsoseparate aircraft operating under instrument flightrules clearances from approach controls and centers.They provide ground control services to aircraft,vehicles, personnel, and equipment on the airportmovement area.

NONCOMMON ROUTE/PORTION− That segmentof a North American Route between the inlandnavigation facility and a designated North Americanterminal.

NON−COOPERATIVE SURVEILLANCE− Anysurveillance system, such as primary radar, that is notdependent upon the presence of any equipment on theaircraft or vehicle to be tracked.

(See COOPERATIVE SURVEILLANCE.)(See RADAR.)

NONDIRECTIONAL BEACON− An L/MF or UHFradio beacon transmitting nondirectional signalswhereby the pilot of an aircraft equipped withdirection finding equipment can determine his/herbearing to or from the radio beacon and “home” on ortrack to or from the station. When the radio beacon isinstalled in conjunction with the Instrument LandingSystem marker, it is normally called a CompassLocator.

(See AUTOMATIC DIRECTION FINDER.)(See COMPASS LOCATOR.)

NONMOVEMENT AREAS− Taxiways and apron(ramp) areas not under the control of air traffic.



PCG N−3

NONPRECISION APPROACH−(See NONPRECISION APPROACHPROCEDURE.)

NONPRECISION APPROACH PROCEDURE− Astandard instrument approach procedure in which noelectronic glideslope is provided; e.g., VOR,TACAN, NDB, LOC, ASR, LDA, or SDFapproaches.

NONRADAR− Precedes other terms and generallymeans without the use of radar, such as:

a. Nonradar Approach. Used to describeinstrument approaches for which course guidance onfinal approach is not provided by ground-basedprecision or surveillance radar. Radar vectors to thefinal approach course may or may not be provided byATC. Examples of nonradar approaches are VOR,NDB, TACAN, ILS, RNAV, and GLS approaches.

(See FINAL APPROACH COURSE.)(See FINAL APPROACH-IFR.)(See INSTRUMENT APPROACHPROCEDURE.)


b. Nonradar Approach Control. An ATC facilityproviding approach control service without the use ofradar.

(See APPROACH CONTROL FACILITY.)(See APPROACH CONTROL SERVICE.)

c. Nonradar Arrival. An aircraft arriving at anairport without radar service or at an airport served bya radar facility and radar contact has not beenestablished or has been terminated due to a lack ofradar service to the airport.

(See RADAR ARRIVAL.)(See RADAR SERVICE.)

d. Nonradar Route. A flight path or route overwhich the pilot is performing his/her own navigation.The pilot may be receiving radar separation, radarmonitoring, or other ATC services while on anonradar route.

(See RADAR ROUTE.)

e. Nonradar Separation. The spacing of aircraft inaccordance with established minima without the useof radar; e.g., vertical, lateral, or longitudinalseparation.

(See RADAR SEPARATION.)

NON−RESTRICTIVE ROUTING (NRR)− Portionsof a proposed route of flight where a user can flight

plan the most advantageous flight path with norequirement to make reference to ground−basedNAVAIDs.

NOPAC−(See NORTH PACIFIC.)

NORDO (No Radio)− Aircraft that cannot or do notcommunicate by radio when radio communication isrequired are referred to as “NORDO.”


NORMAL OPERATING ZONE (NOZ)− The NOZis the operating zone within which aircraft flightremains during normal independent simultaneousparallel ILS approaches.

NORTH AMERICAN ROUTE− A numericallycoded route preplanned over existing airway androute systems to and from specific coastal fixesserving the North Atlantic. North American Routesconsist of the following:

a. Common Route/Portion. That segment of aNorth American Route between the inland navigationfacility and the coastal fix.

b. Noncommon Route/Portion. That segment of aNorth American Route between the inland navigationfacility and a designated North American terminal.

c. Inland Navigation Facility. A navigation aid ona North American Route at which the common routeand/or the noncommon route begins or ends.

d. Coastal Fix. A navigation aid or intersectionwhere an aircraft transitions between the domesticroute structure and the oceanic route structure.

NORTH AMERICAN ROUTE PROGRAM (NRP)−The NRP is a set of rules and procedures which aredesigned to increase the flexibility of user flightplanning within published guidelines.

NORTH ATLANTIC HIGH LEVEL AIRSPACE(NAT HLA)− That volume of airspace (as defined inICAO Document 7030) between FL 285 and FL 420within the Oceanic Control Areas of Bodo Oceanic,Gander Oceanic, New York Oceanic East, Reykjavik,Santa Maria, and Shanwick, excluding the Shannonand Brest Ocean Transition Areas. ICAO Doc 007North Atlantic Operations and Airspace Manualprovides detailed information on related aircraft andoperational requirements.



PCG N−4

NORTH MARK− A beacon data block sent by thehost computer to be displayed by the ARTS on a 360degree bearing at a locally selected radar azimuth anddistance. The North Mark is used to ensure correctrange/azimuth orientation during periods ofCENRAP.

NORTH PACIFIC− An organized route systembetween the Alaskan west coast and Japan.

NOT STANDARD− Varying from what is expectedor published. For use in NOTAMs only.

NOT STD-

(See NOT STANDARD.)

NOTAM−(See NOTICE TO AIRMEN.)

NOTAM [ICAO]− A notice containing informationconcerning the establishment, condition or change inany aeronautical facility, service, procedure orhazard, the timely knowledge of which is essential topersonnel concerned with flight operations.

a. I Distribution− Distribution by means oftelecommunication.

b. II Distribution− Distribution by means otherthan telecommunications.

NOTICE TO AIRMEN (NOTAM)− A noticecontaining information (not known sufficiently inadvance to publicize by other means) concerning theestablishment, condition, or change in anycomponent (facility, service, or procedure of, orhazard in the National Airspace System) the timely

knowledge of which is essential to personnelconcerned with flight operations.

NOTAM(D)− A NOTAM given (in addition to localdissemination) distant dissemination beyond the areaof responsibility of the Flight Service Station. TheseNOTAMs will be stored and available until canceled.

c. FDC NOTAM− A NOTAM regulatory innature, transmitted by USNOF and given systemwide dissemination.

(See ICAO term NOTAM.)

NOTICES TO AIRMEN PUBLICATION− Apublication issued every 28 days, designed primarilyfor the pilot, which contains NOTAMs, graphicnotices, and other information considered essential tothe safety of flight as well as supplemental data toother aeronautical publications. The contractionNTAP is used in NOTAM text.

(See NOTICE TO AIRMEN.)

NRR−(See NON−RESTRICTIVE ROUTING.)

NRS−(See NAVIGATION REFERENCE SYSTEM.)

NTAP−(See NOTICES TO AIRMEN PUBLICATION.)

NUMEROUS TARGETS VICINITY (LOCA-TION)− A traffic advisory issued by ATC to advisepilots that targets on the radar scope are too numerousto issue individually.

(See TRAFFIC ADVISORIES.)



PCG O−1

OOBSTACLE− An existing object, object of naturalgrowth, or terrain at a fixed geographical location orwhich may be expected at a fixed location within aprescribed area with reference to which verticalclearance is or must be provided during flightoperation.

OBSTACLE DEPARTURE PROCEDURE (ODP)−A preplanned instrument flight rule (IFR) departureprocedure printed for pilot use in textual or graphicform to provide obstruction clearance via the leastonerous route from the terminal area to theappropriate en route structure. ODPs are recom-mended for obstruction clearance and may be flownwithout ATC clearance unless an alternate departureprocedure (SID or radar vector) has been specificallyassigned by ATC.


(See STANDARD INSTRUMENTDEPARTURES.)

(Refer to AIM.)

OBSTACLE FREE ZONE− The OFZ is athree−dimensional volume of airspace which protectsfor the transition of aircraft to and from the runway.The OFZ clearing standard precludes taxiing andparked airplanes and object penetrations, except forfrangible NAVAID locations that are fixed byfunction. Additionally, vehicles, equipment, andpersonnel may be authorized by air traffic control toenter the area using the provisions of FAA OrderJO 7110.65, Paragraph 3−1−5, Vehicles/Equipment/Personnal Near/On Runways. The runway OFZ andwhen applicable, the inner-approach OFZ, and theinner-transitional OFZ, comprise the OFZ.

a. Runway OFZ. The runway OFZ is a definedvolume of airspace centered above the runway. Therunway OFZ is the airspace above a surface whoseelevation at any point is the same as the elevation ofthe nearest point on the runway centerline. Therunway OFZ extends 200 feet beyond each end of therunway. The width is as follows:

1. For runways serving large airplanes, thegreater of:

(a) 400 feet, or

(b) 180 feet, plus the wingspan of the mostdemanding airplane, plus 20 feet per 1,000 feet ofairport elevation.

2. For runways serving only small airplanes:

(a) 300 feet for precision instrument run-ways.

(b) 250 feet for other runways serving smallairplanes with approach speeds of 50 knots, or more.

(c) 120 feet for other runways serving smallairplanes with approach speeds of less than 50 knots.

b. Inner-approach OFZ. The inner-approach OFZis a defined volume of airspace centered on theapproach area. The inner-approach OFZ applies onlyto runways with an approach lighting system. Theinner-approach OFZ begins 200 feet from the runwaythreshold at the same elevation as the runwaythreshold and extends 200 feet beyond the last lightunit in the approach lighting system. The width of theinner-approach OFZ is the same as the runway OFZand rises at a slope of 50 (horizontal) to 1 (vertical)from the beginning.

c. Inner-transitional OFZ. The inner transitionalsurface OFZ is a defined volume of airspace along thesides of the runway and inner-approach OFZ andapplies only to precision instrument runways. Theinner-transitional surface OFZ slopes 3 (horizontal)to 1 (vertical) out from the edges of the runway OFZand inner-approach OFZ to a height of 150 feet abovethe established airport elevation.

(Refer to AC 150/5300-13, Chapter 3.)(Refer to FAA Order JO 7110.65, Para 3−1−5,Vehicles/Equipment/Personnel Near/OnRunways.)

OBSTRUCTION− Any object/obstacle exceedingthe obstruction standards specified by 14 CFRPart 77, Subpart C.

OBSTRUCTION LIGHT− A light or one of a groupof lights, usually red or white, frequently mounted ona surface structure or natural terrain to warn pilots ofthe presence of an obstruction.

OCEANIC AIRSPACE− Airspace over the oceans ofthe world, considered international airspace, whereoceanic separation and procedures per the Interna-tional Civil Aviation Organization are applied.Responsibility for the provisions of air traffic control


PCG O−2

service in this airspace is delegated to variouscountries, based generally upon geographic proxim-ity and the availability of the required resources.

OCEANIC ERROR REPORT− A report filed whenATC observes an Oceanic Error as defined by FAAOrder 7110.82, Reporting Oceanic Errors.

OCEANIC PUBLISHED ROUTE− A route estab-lished in international airspace and charted ordescribed in flight information publications, such asRoute Charts, DOD En route Charts, ChartSupplements, NOTAMs, and Track Messages.

OCEANIC TRANSITION ROUTE− An ATS routeestablished for the purpose of transitioning aircraftto/from an organized track system.

ODP−(See OBSTACLE DEPARTURE PROCEDURE.)

OFF COURSE− A term used to describe a situationwhere an aircraft has reported a position fix or isobserved on radar at a point not on the ATC-approvedroute of flight.

OFF-ROUTE VECTOR− A vector by ATC whichtakes an aircraft off a previously assigned route.Altitudes assigned by ATC during such vectorsprovide required obstacle clearance.

OFFSET PARALLEL RUNWAYS− Staggeredrunways having centerlines which are parallel.

OFFSHORE/CONTROL AIRSPACE AREA− Thatportion of airspace between the U.S. 12 NM limit andthe oceanic CTA/FIR boundary within which airtraffic control is exercised. These areas areestablished to provide air traffic control services.Offshore/Control Airspace Areas may be classifiedas either Class A airspace or Class E airspace.

OFT−(See OUTER FIX TIME.)

OM−(See OUTER MARKER.)

ON COURSE−

a. Used to indicate that an aircraft is established onthe route centerline.

b. Used by ATC to advise a pilot making a radarapproach that his/her aircraft is lined up on the finalapproach course.

(See ON-COURSE INDICATION.)

ON-COURSE INDICATION− An indication on aninstrument, which provides the pilot a visual meansof determining that the aircraft is located on thecenterline of a given navigational track, or anindication on a radar scope that an aircraft is on agiven track.

ONE-MINUTE WEATHER− The most recent oneminute updated weather broadcast received by a pilotfrom an uncontrolled airport ASOS/AWOS.

ONER−(See OCEANIC NAVIGATIONAL ERRORREPORT.)

OPERATIONAL−(See DUE REGARD.)

OPERATIONS SPECIFICATIONS [ICAO]− Theauthorizations, conditions and limitations associatedwith the air operator certificate and subject to theconditions in the operations manual.

OPPOSITE DIRECTION AIRCRAFT− Aircraft areoperating in opposite directions when:

a. They are following the same track in reciprocaldirections; or

b. Their tracks are parallel and the aircraft areflying in reciprocal directions; or

c. Their tracks intersect at an angle of more than135�.

OPTION APPROACH− An approach requested andconducted by a pilot which will result in either atouch-and-go, missed approach, low approach,stop-and-go, or full stop landing. Pilots should adviseATC if they decide to remain on the runway, of anydelay in their stop and go, delay clearing the runway,or are unable to comply with the instruction(s).

(See CLEARED FOR THE OPTION.)(Refer to AIM.)

ORGANIZED TRACK SYSTEM− A series of ATSroutes which are fixed and charted; i.e., CEP,NOPAC, or flexible and described by NOTAM; i.e.,NAT TRACK MESSAGE.


PCG O−3

OFF−ROUTE OBSTRUCTION CLEARANCE AL-TITUDE (OROCA)− An off-route altitude whichprovides obstruction clearance with a 1,000 footbuffer in non−mountainous terrain areas and a 2,000foot buffer in designated mountainous areas withinthe United States. This altitude may not providesignal coverage from ground-based navigationalaids, air traffic control radar, or communicationscoverage.

OTR−(See OCEANIC TRANSITION ROUTE.)

OTS−(See ORGANIZED TRACK SYSTEM.)

OUT− The conversation is ended and no response isexpected.

OUT OF SERVICE/UNSERVICEABLE (U/S)−When a piece of equipment, a NAVAID, a facility ora service is not operational, certified (if required) andimmediately “available” for Air Traffic or public use.

OUTER AREA (associated with Class C airspace)−Non−regulatory airspace surrounding designatedClass C airspace airports wherein ATC provides radarvectoring and sequencing on a full-time basis for allIFR and participating VFR aircraft. The serviceprovided in the outer area is called Class C servicewhich includes: IFR/IFR−IFR separation; IFR/VFR−traffic advisories and conflict resolution; andVFR/VFR−traffic advisories and, as appropriate,safety alerts. The normal radius will be 20 nauticalmiles with some variations based on site-specificrequirements. The outer area extends outward fromthe primary Class C airspace airport and extends fromthe lower limits of radar/radio coverage up to theceiling of the approach control’s delegated airspaceexcluding the Class C charted area and other airspaceas appropriate.

(See CONFLICT RESOLUTION.)(See CONTROLLED AIRSPACE.)

OUTER COMPASS LOCATOR−(See COMPASS LOCATOR.)

OUTER FIX− A general term used within ATC todescribe fixes in the terminal area, other than the finalapproach fix. Aircraft are normally cleared to thesefixes by an Air Route Traffic Control Center or anApproach Control Facility. Aircraft are normallycleared from these fixes to the final approach fix orfinal approach course.

OR

OUTER FIX− An adapted fix along the convertedroute of flight, prior to the meter fix, for whichcrossing times are calculated and displayed in themetering position list.

OUTER FIX ARC− A semicircle, usually about a50−70 mile radius from a meter fix, usually in highaltitude, which is used by CTAS/ERAM to calculateouter fix times and determine appropriate sectormeter list assignments for aircraft on an establishedarrival route that will traverse the arc.

OUTER FIX TIME− A calculated time to depart theouter fix in order to cross the vertex at the ACLT. Thetime reflects descent speed adjustments and anyapplicable delay time that must be absorbed prior tocrossing the meter fix.

OUTER MARKER− A marker beacon at or near theglideslope intercept altitude of an ILS approach. It iskeyed to transmit two dashes per second on a 400 Hztone, which is received aurally and visually bycompatible airborne equipment. The OM is normallylocated four to seven miles from the runway thresholdon the extended centerline of the runway.

(See INSTRUMENT LANDING SYSTEM.)(See MARKER BEACON.)(Refer to AIM.)

OVER− My transmission is ended; I expect aresponse.

OVERHEAD MANEUVER− A series of predeter-mined maneuvers prescribed for aircraft (often information) for entry into the visual flight rules (VFR)traffic pattern and to proceed to a landing. Anoverhead maneuver is not an instrument flight rules(IFR) approach procedure. An aircraft executing anoverhead maneuver is considered VFR and the IFRflight plan is canceled when the aircraft reaches the“initial point” on the initial approach portion of themaneuver. The pattern usually specifies thefollowing:

a. The radio contact required of the pilot.

b. The speed to be maintained.

c. An initial approach 3 to 5 miles in length.

d. An elliptical pattern consisting of two 180degree turns.

e. A break point at which the first 180 degree turnis started.

f. The direction of turns.



PCG O−4

g. Altitude (at least 500 feet above the convention-al pattern).

h. A “Roll-out” on final approach not less than 1/4mile from the landing threshold and not less than 300feet above the ground.

OVERLYING CENTER− The ARTCC facility thatis responsible for arrival/departure operations at aspecific terminal.


PCG P−1

PP TIME−

(See PROPOSED DEPARTURE TIME.)

P-ACP−(See PREARRANGED COORDINATIONPROCEDURES.)

PAN-PAN− The international radio-telephony urgen-cy signal. When repeated three times, indicatesuncertainty or alert followed by the nature of theurgency.

(See MAYDAY.)(Refer to AIM.)

PAR−(See PRECISION APPROACH RADAR.)

PAR [ICAO]−(See ICAO Term PRECISION APPROACHRADAR.)

PARALLEL ILS APPROACHES− Approaches toparallel runways by IFR aircraft which, whenestablished inbound toward the airport on theadjacent final approach courses, are radar-separatedby at least 2 miles.

(See FINAL APPROACH COURSE.)(See SIMULTANEOUS ILS APPROACHES.)

PARALLEL OFFSET ROUTE− A parallel track tothe left or right of the designated or establishedairway/route. Normally associated with Area Navi-gation (RNAV) operations.

(See AREA NAVIGATION.)

PARALLEL RUNWAYS− Two or more runways atthe same airport whose centerlines are parallel. Inaddition to runway number, parallel runways aredesignated as L (left) and R (right) or, if three parallelrunways exist, L (left), C (center), and R (right).

PBCT−(See PROPOSED BOUNDARY CROSSINGTIME.)

PBN−(See ICAO Term PERFORMANCE−BASEDNAVIGATION.)

PDC−(See PRE−DEPARTURE CLEARANCE.)

PERFORMANCE−BASED NAVIGATION (PBN)[ICAO]− Area navigation based on performancerequirements for aircraft operating along an ATSroute, on an instrument approach procedure or in adesignated airspace.

Note: Performance requirements are expressed innavigation specifications (RNAV specification,RNP specification) in terms of accuracy, integrity,continuity, availability, and functionality needed forthe proposed operation in the context of aparticular airspace concept.

PERMANENT ECHO− Radar signals reflected fromfixed objects on the earth’s surface; e.g., buildings,towers, terrain. Permanent echoes are distinguishedfrom “ground clutter” by being definable locationsrather than large areas. Under certain conditions theymay be used to check radar alignment.

PHOTO RECONNAISSANCE− Military activitythat requires locating individual photo targets andnavigating to the targets at a preplanned angle andaltitude. The activity normally requires a lateral routewidth of 16 NM and altitude range of 1,500 feet to10,000 feet AGL.

PILOT BRIEFING− A service provided by the FSSto assist pilots in flight planning. Briefing items mayinclude weather information, NOTAMS, militaryactivities, flow control information, and other itemsas requested.

(Refer to AIM.)

PILOT IN COMMAND− The pilot responsible forthe operation and safety of an aircraft during flighttime.


PILOT WEATHER REPORT− A report of meteoro-logical phenomena encountered by aircraft in flight.

(Refer to AIM.)

PILOT’S DISCRETION− When used in conjunc-tion with altitude assignments, means that ATC hasoffered the pilot the option of starting climb ordescent whenever he/she wishes and conducting theclimb or descent at any rate he/she wishes. He/shemay temporarily level off at any intermediatealtitude. However, once he/she has vacated analtitude, he/she may not return to that altitude.


PCG P−2

PIREP−(See PILOT WEATHER REPORT.)

PITCH POINT− A fix/waypoint that serves as atransition point from a departure procedure or the lowaltitude ground−based navigation structure into thehigh altitude waypoint system.

PLANS DISPLAY− A display available in EDSTthat provides detailed flight plan and predictedconflict information in textual format for requestedCurrent Plans and all Trial Plans.

(See EN ROUTE DECISION SUPPORT TOOL)

POFZ−(See PRECISION OBSTACLE FREE ZONE.)

POINT OUT−(See RADAR POINT OUT.)

POINT−TO−POINT (PTP)− A level of NRR servicefor aircraft that is based on traditional waypoints intheir FMSs or RNAV equipage.

POLAR TRACK STRUCTURE− A system oforganized routes between Iceland and Alaska whichoverlie Canadian MNPS Airspace.

POSITION REPORT− A report over a knownlocation as transmitted by an aircraft to ATC.

(Refer to AIM.)

POSITION SYMBOL− A computer-generatedindication shown on a radar display to indicate themode of tracking.

POSITIVE CONTROL− The separation of all airtraffic within designated airspace by air trafficcontrol.

PRACTICE INSTRUMENT APPROACH− Aninstrument approach procedure conducted by a VFRor an IFR aircraft for the purpose of pilot training orproficiency demonstrations.

PRE−DEPARTURE CLEARANCE− An applicationwith the Terminal Data Link System (TDLS) thatprovides clearance information to subscribers,through a service provider, in text to the cockpit orgate printer.

PREARRANGED COORDINATION− A standard-ized procedure which permits an air traffic controllerto enter the airspace assigned to another air trafficcontroller without verbal coordination. The proce-dures are defined in a facility directive which ensuresapproved separation between aircraft.

PREARRANGED COORDINATION PROCE-DURES− A facility’s standardized procedure thatdescribes the process by which one controller shallallow an aircraft to penetrate or transit anothercontroller’s airspace in a manner that assuresapproved separation without individual coordinationfor each aircraft.

PRECIPITATION− Any or all forms of waterparticles (rain, sleet, hail, or snow) that fall from theatmosphere and reach the surface.

PRECIPITATION RADAR WEATHER DESCRIP-TIONS− Existing radar systems cannot detectturbulence. However, there is a direct correlationbetween the degree of turbulence and other weatherfeatures associated with thunderstorms and theweather radar precipitation intensity. Controllers willissue (where capable) precipitation intensity asobserved by radar when using weather and radarprocessor (WARP) or NAS ground−based digitalradars with weather capabilities. When precipitationintensity information is not available, the intensitywill be described as UNKNOWN. When intensitylevels can be determined, they shall be described as:

a. LIGHT (< 26 dBZ)

b. MODERATE (26 to 40 dBZ)

c. HEAVY (> 40 to 50 dBZ)

d. EXTREME (> 50 dBZ)(Refer to AC 00−45, Aviation Weather Services.)

PRECISION APPROACH−(See PRECISION APPROACH PROCEDURE.)

PRECISION APPROACH PROCEDURE− Astandard instrument approach procedure in which anelectronic glideslope or other type of glidepath isprovided; e.g., ILS, PAR, and GLS.

(See INSTRUMENT LANDING SYSTEM.)(See PRECISION APPROACH RADAR.)

PRECISION APPROACH RADAR− Radar equip-ment in some ATC facilities operated by the FAAand/or the military services at joint-use civil/militarylocations and separate military installations to detectand display azimuth, elevation, and range of aircrafton the final approach course to a runway. Thisequipment may be used to monitor certain non−radarapproaches, but is primarily used to conduct aprecision instrument approach (PAR) wherein thecontroller issues guidance instructions to the pilotbased on the aircraft’s position in relation to the finalapproach course (azimuth), the glidepath (elevation),



PCG P−3

and the distance (range) from the touchdown point onthe runway as displayed on the radar scope.

Note: The abbreviation “PAR” is also used todenote preferential arrival routes in ARTCCcomputers.

(See GLIDEPATH.)(See PAR.)(See PREFERENTIAL ROUTES.)(See ICAO term PRECISION APPROACHRADAR.)

(Refer to AIM.)

PRECISION APPROACH RADAR [ICAO]− Pri-mary radar equipment used to determine the positionof an aircraft during final approach, in terms of lateraland vertical deviations relative to a nominal approachpath, and in range relative to touchdown.

Note: Precision approach radars are designed toenable pilots of aircraft to be given guidance byradio communication during the final stages of theapproach to land.

PRECISION OBSTACLE FREE ZONE (POFZ)−An 800 foot wide by 200 foot long area centered onthe runway centerline adjacent to the thresholddesigned to protect aircraft flying precisionapproaches from ground vehicles and other aircraftwhen ceiling is less than 250 feet or visibility is lessthan 3/4 statute mile (or runway visual range below4,000 feet.)

PRECISION RUNWAY MONITOR (PRM)SYSTEM− Provides air traffic controllersmonitoring the NTZ during simultaneous closeparallel PRM approaches with precision, high updaterate secondary surveillance data. The high update ratesurveillance sensor component of the PRM system isonly required for specific runway or approach courseseparation. The high resolution color monitoringdisplay, Final Monitor Aid (FMA) of the PRMsystem, or other FMA with the same capability,presents NTZ surveillance track data to controllersalong with detailed maps depicting approaches andno transgression zone and is required for allsimultaneous close parallel PRM NTZ monitoringoperations.

(Refer to AIM)

PREDICTIVE WIND SHEAR ALERT SYSTEM(PWS)− A self−contained system used on board someaircraft to alert the flight crew to the presence of apotential wind shear. PWS systems typically monitor3 miles ahead and 25 degrees left and right of the

aircraft’s heading at or below 1200’ AGL. Departingflights may receive a wind shear alert after they startthe takeoff roll and may elect to abort the takeoff.Aircraft on approach receiving an alert may elect togo around or perform a wind shear escape maneuver.

PREFERENTIAL ROUTES− Preferential routes(PDRs, PARs, and PDARs) are adapted in ARTCCcomputers to accomplish inter/intrafacility controllercoordination and to assure that flight data is posted atthe proper control positions. Locations having a needfor these specific inbound and outbound routesnormally publish such routes in local facilitybulletins, and their use by pilots minimizes flightplan route amendments. When the workload or trafficsituation permits, controllers normally provide radarvectors or assign requested routes to minimizecircuitous routing. Preferential routes are usuallyconfined to one ARTCC’s area and are referred to bythe following names or acronyms:

a. Preferential Departure Route (PDR). A specificdeparture route from an airport or terminal area to anen route point where there is no further need for flowcontrol. It may be included in an InstrumentDeparture Procedure (DP) or a Preferred IFR Route.

b. Preferential Arrival Route (PAR). A specificarrival route from an appropriate en route point to anairport or terminal area. It may be included in aStandard Terminal Arrival (STAR) or a Preferred IFRRoute. The abbreviation “PAR” is used primarilywithin the ARTCC and should not be confused withthe abbreviation for Precision Approach Radar.

c. Preferential Departure and Arrival Route(PDAR). A route between two terminals which arewithin or immediately adjacent to one ARTCC’s area.PDARs are not synonymous with Preferred IFRRoutes but may be listed as such as they doaccomplish essentially the same purpose.

(See PREFERRED IFR ROUTES.)

PREFERRED IFR ROUTES− Routes establishedbetween busier airports to increase system efficiencyand capacity. They normally extend through one ormore ARTCC areas and are designed to achievebalanced traffic flows among high density terminals.IFR clearances are issued on the basis of these routesexcept when severe weather avoidance procedures orother factors dictate otherwise. Preferred IFR Routesare listed in the Chart Supplement U.S. If a flight isplanned to or from an area having such routes but thedeparture or arrival point is not listed in the ChartSupplement U.S., pilots may use that part of a



PCG P−4

Preferred IFR Route which is appropriate for thedeparture or arrival point that is listed. Preferred IFRRoutes are correlated with DPs and STARs and maybe defined by airways, jet routes, direct routesbetween NAVAIDs, Waypoints, NAVAID radials/DME, or any combinations thereof.

(See CENTER’S AREA.)(See INSTRUMENT DEPARTUREPROCEDURE.)

(See PREFERENTIAL ROUTES.)(See STANDARD TERMINAL ARRIVAL.)

(Refer to CHART SUPPLEMENT U.S.)(Refer to NOTICES TO AIRMEN PUBLICATION.)

PRE-FLIGHT PILOT BRIEFING−(See PILOT BRIEFING.)

PREVAILING VISIBILITY−(See VISIBILITY.)

PRIMARY RADAR TARGET− An analog or digitaltarget, exclusive of a secondary radar target,presented on a radar display.

PRM−(See AREA NAVIGATION (RNAV) GLOBALPOSITIONING SYSTEM (GPS) PRECISIONRUNWAY MONITORING (PRM) APPROACH.)

(See PRM APPROACH.)(See PRECISION RUNWAY MONITORSYSTEM.)

PRM APPROACH− An instrument approachprocedure titled ILS PRM, RNAV PRM, LDA PRM,or GLS PRM conducted to parallel runwaysseparated by less than 4,300 feet and at least 3,000feet where independent closely spaced approachesare permitted. Use of an enhanced display withalerting, a No Transgression Zone (NTZ), secondarymonitor frequency, pilot PRM training, andpublication of an Attention All Users Page arerequired for all PRM approaches. Depending on therunway spacing, the approach courses may be parallelor one approach course must be offset. PRMprocedures are also used to conduct SimultaneousOffset Instrument Approach (SOIA) operations. InSOIA, one straight−in ILS PRM, RNAV PRM, GLSPRM, and one offset LDA PRM, RNAV PRM orGLS PRM approach are utilized. PRM proceduresare terminated and a visual segment begins at theoffset approach missed approach point where theminimum distance between the approach courses is

3000 feet. Runway spacing can be as close as 750feet.

(Refer to AIM.)

PROCEDURAL CONTROL [ICAO]– Term used toindicate that information derived from an ATSsurveillance system is not required for the provisionof air traffic control service.

PROCEDURAL SEPARATION [ICAO]– The sepa-ration used when providing procedural control.

PROCEDURE TURN− The maneuver prescribedwhen it is necessary to reverse direction to establishan aircraft on the intermediate approach segment orfinal approach course. The outbound course,direction of turn, distance within which the turn mustbe completed, and minimum altitude are specified inthe procedure. However, unless otherwise restricted,the point at which the turn may be commenced andthe type and rate of turn are left to the discretion of thepilot.

(See ICAO term PROCEDURE TURN.)

PROCEDURE TURN [ICAO]− A maneuver inwhich a turn is made away from a designated trackfollowed by a turn in the opposite direction to permitthe aircraft to intercept and proceed along thereciprocal of the designated track.

Note 1: Procedure turns are designated “left” or“right” according to the direction of the initial turn.

Note 2: Procedure turns may be designated asbeing made either in level flight or whiledescending, according to the circumstances ofeach individual approach procedure.

PROCEDURE TURN INBOUND− That point of aprocedure turn maneuver where course reversal hasbeen completed and an aircraft is established inboundon the intermediate approach segment or finalapproach course. A report of “procedure turninbound” is normally used by ATC as a positionreport for separation purposes.

(See FINAL APPROACH COURSE.)(See PROCEDURE TURN.)(See SEGMENTS OF AN INSTRUMENTAPPROACH PROCEDURE.)

PROFILE DESCENT− An uninterrupted descent(except where level flight is required for speedadjustment; e.g., 250 knots at 10,000 feet MSL) fromcruising altitude/level to interception of a glideslopeor to a minimum altitude specified for the initial orintermediate approach segment of a nonprecisioninstrument approach. The profile descent normally



PCG P−5

terminates at the approach gate or where theglideslope or other appropriate minimum altitude isintercepted.

PROGRESS REPORT−(See POSITION REPORT.)

PROGRESSIVE TAXI− Precise taxi instructionsgiven to a pilot unfamiliar with the airport or issuedin stages as the aircraft proceeds along the taxi route.

PROHIBITED AREA−(See SPECIAL USE AIRSPACE.)(See ICAO term PROHIBITED AREA.)

PROHIBITED AREA [ICAO]− An airspace ofdefined dimensions, above the land areas or territorialwaters of a State, within which the flight of aircraftis prohibited.

PROMINENT OBSTACLE– An obstacle that meetsone or more of the following conditions:

a. An obstacle which stands out beyond theadjacent surface of surrounding terrain and immedi-ately projects a noticeable hazard to aircraft in flight.

b. An obstacle, not characterized as low and closein, whose height is no less than 300 feet above thedeparture end of takeoff runway (DER) elevation, iswithin 10NM from the DER, and that penetrates thatairport/heliport’s diverse departure obstacle clear-ance surface (OCS).

c. An obstacle beyond 10NM from an airport/heli-port that requires an obstacle departure procedure(ODP) to ensure obstacle avoidance.

(See OBSTACLE.)(See OBSTRUCTION.)

PROPELLER (PROP) WASH (PROP BLAST)− Thedisturbed mass of air generated by the motion of apropeller.

PROPOSED BOUNDARY CROSSING TIME−Each center has a PBCT parameter for each internalairport. Proposed internal flight plans are transmitted

to the adjacent center if the flight time along theproposed route from the departure airport to thecenter boundary is less than or equal to the value ofPBCT or if airport adaptation specifies transmissionregardless of PBCT.

PROPOSED DEPARTURE TIME− The time that theaircraft expects to become airborne.

PROTECTED AIRSPACE− The airspace on eitherside of an oceanic route/track that is equal to one-halfthe lateral separation minimum except wherereduction of protected airspace has been authorized.

PROTECTED SEGMENT- The protected segment isa segment on the amended TFM route that is to beinhibited from automatic adapted route alteration byERAM.

PT−(See PROCEDURE TURN.)

PTP−(See POINT−TO−POINT.)

PTS−(See POLAR TRACK STRUCTURE.)

PUBLISHED INSTRUMENT APPROACHPROCEDURE VISUAL SEGMENT− A segment onan IAP chart annotated as “Fly Visual to Airport” or“Fly Visual.” A dashed arrow will indicate the visualflight path on the profile and plan view with anassociated note on the approximate heading anddistance. The visual segment should be flown as adead reckoning course while maintaining visualconditions.

PUBLISHED ROUTE− A route for which an IFRaltitude has been established and published; e.g.,Federal Airways, Jet Routes, Area NavigationRoutes, Specified Direct Routes.

PWS−(See PREDICTIVE WIND SHEAR ALERTSYSTEM.)



PCG Q−1

QQ ROUTE− ‘Q’ is the designator assigned topublished RNAV routes used by the United States.

QFE− The atmospheric pressure at aerodromeelevation (or at runway threshold).

QNE− The barometric pressure used for the standardaltimeter setting (29.92 inches Hg.).

QNH− The barometric pressure as reported by aparticular station.

QUADRANT− A quarter part of a circle, centered ona NAVAID, oriented clockwise from magnetic north

as follows: NE quadrant 000-089, SE quadrant090-179, SW quadrant 180-269, NW quadrant270-359.

QUEUING−

(See STAGING/QUEUING.)

QUICK LOOK− A feature of the EAS and ARTSwhich provides the controller the capability todisplay full data blocks of tracked aircraft from othercontrol positions.


PCG R−1

RRADAR− A device that provides information onrange, azimuth, and/or elevation of objects bymeasuring the time interval between transmissionand reception of directional radio pulses andcorrelating the angular orientation of the radiatedantenna beam or beams in azimuth and/or elevation.

a. Primary Radar− A radar system in which aminute portion of a radio pulse transmitted from a siteis reflected by an object and then received back at thatsite for processing and display at an air traffic controlfacility.

b. Secondary Radar/Radar Beacon (ATCRBS)− Aradar system in which the object to be detected isfitted with cooperative equipment in the form of aradio receiver/transmitter (transponder). Radarpulses transmitted from the searching transmitter/re-ceiver (interrogator) site are received in thecooperative equipment and used to trigger adistinctive transmission from the transponder. Thisreply transmission, rather than a reflected signal, isthen received back at the transmitter/receiver site forprocessing and display at an air traffic control facility.

(See COOPERATIVE SURVEILLANCE.)(See INTERROGATOR.)(See NON−COOPERATIVE SURVEILLANCE.)(See TRANSPONDER.)(See ICAO term RADAR.)(Refer to AIM.)

RADAR [ICAO]− A radio detection device whichprovides information on range, azimuth and/orelevation of objects.

a. Primary Radar− Radar system which usesreflected radio signals.

b. Secondary Radar− Radar system wherein aradio signal transmitted from a radar station initiatesthe transmission of a radio signal from anotherstation.

RADAR ADVISORY− The provision of advice andinformation based on radar observations.

(See ADVISORY SERVICE.)

RADAR ALTIMETER−(See RADIO ALTIMETER.)

RADAR APPROACH− An instrument approachprocedure which utilizes Precision Approach Radar(PAR) or Airport Surveillance Radar (ASR).

(See AIRPORT SURVEILLANCE RADAR.)(See INSTRUMENT APPROACHPROCEDURE.)

(See PRECISION APPROACH RADAR.)(See SURVEILLANCE APPROACH.)(See ICAO term RADAR APPROACH.)(Refer to AIM.)

RADAR APPROACH [ICAO]− An approach,executed by an aircraft, under the direction of a radarcontroller.

RADAR APPROACH CONTROL FACILITY− Aterminal ATC facility that uses radar and nonradarcapabilities to provide approach control services toaircraft arriving, departing, or transiting airspacecontrolled by the facility.

(See APPROACH CONTROL SERVICE.)

a. Provides radar ATC services to aircraftoperating in the vicinity of one or more civil and/ormilitary airports in a terminal area. The facility mayprovide services of a ground controlled approach(GCA); i.e., ASR and PAR approaches. A radarapproach control facility may be operated by FAA,USAF, US Army, USN, USMC, or jointly by FAAand a military service. Specific facility nomencla-tures are used for administrative purposes only andare related to the physical location of the facility andthe operating service generally as follows:

1. Army Radar Approach Control (ARAC) (US Army).

2. Radar Air Traffic Control Facility (RATCF)(USN/FAA and USMC/FAA).

3. Radar Approach Control (RAPCON) (USAF/FAA, USN/FAA, and USMC/FAA).

4. Terminal Radar Approach Control(TRACON) (FAA).

5. Air Traffic Control Tower (ATCT) (FAA).(Only those towers delegated approach controlauthority.)

RADAR ARRIVAL− An aircraft arriving at anairport served by a radar facility and in radar contactwith the facility.

(See NONRADAR.)



PCG R−2

RADAR BEACON−(See RADAR.)

RADAR CLUTTER [ICAO]− The visual indicationon a radar display of unwanted signals.

RADAR CONTACT−

a. Used by ATC to inform an aircraft that it isidentified using an approved ATC surveillancesource on an air traffic controller’s display and thatradar flight following will be provided until radarservice is terminated. Radar service may also beprovided within the limits of necessity and capability.When a pilot is informed of “radar contact,” he/sheautomatically discontinues reporting over compuls-ory reporting points.

(See ATC SURVEILLANCE SOURCE.)(See RADAR CONTACT LOST.)(See RADAR FLIGHT FOLLOWING.)(See RADAR SERVICE.)(See RADAR SERVICE TERMINATED.)(Refer to AIM.)

b. The term used to inform the controller that theaircraft is identified and approval is granted for theaircraft to enter the receiving controllers airspace.

(See ICAO term RADAR CONTACT.)

RADAR CONTACT [ICAO]− The situation whichexists when the radar blip or radar position symbol ofa particular aircraft is seen and identified on a radardisplay.

RADAR CONTACT LOST− Used by ATC to informa pilot that the surveillance data used to determine theaircraft’s position is no longer being received, or is nolonger reliable and radar service is no longer beingprovided. The loss may be attributed to severalfactors including the aircraft merging with weather orground clutter, the aircraft operating below radar lineof sight coverage, the aircraft entering an area of poorradar return, failure of the aircraft’s equipment, orfailure of the surveillance equipment.

(See CLUTTER.)(See RADAR CONTACT.)

RADAR ENVIRONMENT− An area in which radarservice may be provided.

(See ADDITIONAL SERVICES.)(See RADAR CONTACT.)(See RADAR SERVICE.)(See TRAFFIC ADVISORIES.)

RADAR FLIGHT FOLLOWING− The observationof the progress of radar−identified aircraft, whoseprimary navigation is being provided by the pilot,wherein the controller retains and correlates theaircraft identity with the appropriate target or targetsymbol displayed on the radar scope.

(See RADAR CONTACT.)(See RADAR SERVICE.)(Refer to AIM.)

RADAR IDENTIFICATION− The process ofascertaining that an observed radar target is the radarreturn from a particular aircraft.

(See RADAR CONTACT.)(See RADAR SERVICE.)

RADAR IDENTIFIED AIRCRAFT− An aircraft, theposition of which has been correlated with anobserved target or symbol on the radar display.

(See RADAR CONTACT.)(See RADAR CONTACT LOST.)

RADAR MONITORING−(See RADAR SERVICE.)

RADAR NAVIGATIONAL GUIDANCE−(See RADAR SERVICE.)

RADAR POINT OUT− An action taken by acontroller to transfer the radar identification of anaircraft to another controller if the aircraft will or mayenter the airspace or protected airspace of anothercontroller and radio communications will not betransferred.

RADAR REQUIRED− A term displayed on chartsand approach plates and included in FDC NOTAMsto alert pilots that segments of either an instrumentapproach procedure or a route are not navigablebecause of either the absence or unusability of aNAVAID. The pilot can expect to be provided radarnavigational guidance while transiting segmentslabeled with this term.

(See RADAR ROUTE.)(See RADAR SERVICE.)

RADAR ROUTE− A flight path or route over whichan aircraft is vectored. Navigational guidance andaltitude assignments are provided by ATC.

(See FLIGHT PATH.)(See ROUTE.)

RADAR SEPARATION−(See RADAR SERVICE.)

RADAR SERVICE− A term which encompasses oneor more of the following services based on the use of


PCG R−3

radar which can be provided by a controller to a pilotof a radar identified aircraft.

a. Radar Monitoring− The radar flight-followingof aircraft, whose primary navigation is beingperformed by the pilot, to observe and note deviationsfrom its authorized flight path, airway, or route.When being applied specifically to radar monitoringof instrument approaches; i.e., with precisionapproach radar (PAR) or radar monitoring ofsimultaneous ILS,RNAV and GLS approaches, itincludes advice and instructions whenever an aircraftnears or exceeds the prescribed PAR safety limit orsimultaneous ILS RNAV and GLS no transgressionzone.

(See ADDITIONAL SERVICES.)(See TRAFFIC ADVISORIES.)

b. Radar Navigational Guidance− Vectoringaircraft to provide course guidance.

c. Radar Separation− Radar spacing of aircraft inaccordance with established minima.

(See ICAO term RADAR SERVICE.)

RADAR SERVICE [ICAO]− Term used to indicatea service provided directly by means of radar.

a. Monitoring− The use of radar for the purpose ofproviding aircraft with information and advicerelative to significant deviations from nominal flightpath.

b. Separation− The separation used when aircraftposition information is derived from radar sources.

RADAR SERVICE TERMINATED− Used by ATCto inform a pilot that he/she will no longer beprovided any of the services that could be receivedwhile in radar contact. Radar service is automaticallyterminated, and the pilot is not advised in thefollowing cases:

a. An aircraft cancels its IFR flight plan, exceptwithin Class B airspace, Class C airspace, a TRSA,or where Basic Radar service is provided.

b. An aircraft conducting an instrument, visual, orcontact approach has landed or has been instructed tochange to advisory frequency.

c. An arriving VFR aircraft, receiving radarservice to a tower-controlled airport within Class Bairspace, Class C airspace, a TRSA, or wheresequencing service is provided, has landed; or to allother airports, is instructed to change to tower oradvisory frequency.

d. An aircraft completes a radar approach.

RADAR SURVEILLANCE− The radar observationof a given geographical area for the purpose ofperforming some radar function.

RADAR TRAFFIC ADVISORIES− Advisoriesissued to alert pilots to known or observed radartraffic which may affect the intended route of flightof their aircraft.

(See TRAFFIC ADVISORIES.)

RADAR TRAFFIC INFORMATION SERVICE−(See TRAFFIC ADVISORIES.)

RADAR VECTORING [ICAO]− Provision ofnavigational guidance to aircraft in the form ofspecific headings, based on the use of radar.

RADIAL− A magnetic bearing extending from aVOR/VORTAC/TACAN navigation facility.

RADIO−a. A device used for communication.b. Used to refer to a flight service station; e.g.,

“Seattle Radio” is used to call Seattle FSS.

RADIO ALTIMETER− Aircraft equipment whichmakes use of the reflection of radio waves from theground to determine the height of the aircraft abovethe surface.

RADIO BEACON−(See NONDIRECTIONAL BEACON.)

RADIO DETECTION AND RANGING−(See RADAR.)

RADIO MAGNETIC INDICATOR− An aircraftnavigational instrument coupled with a gyro compassor similar compass that indicates the direction of aselected NAVAID and indicates bearing with respectto the heading of the aircraft.

RAIS−(See REMOTE AIRPORT INFORMATIONSERVICE.)

RAMP−(See APRON.)

RANDOM ALTITUDE− An altitude inappropriatefor direction of flight and/or not in accordance withFAA Order JO 7110.65, Paragraph 4−5−1, VER-TICAL SEPARATION MINIMA.

RANDOM ROUTE− Any route not established orcharted/published or not otherwise available to allusers.

RC−(See ROAD RECONNAISSANCE.)


PCG R−4

RCAG−(See REMOTE COMMUNICATIONSAIR/GROUND FACILITY.)

RCC−(See RESCUE COORDINATION CENTER.)

RCO−(See REMOTE COMMUNICATIONS OUTLET.)

RCR−(See RUNWAY CONDITION READING.)

READ BACK− Repeat my message back to me.

RECEIVER AUTONOMOUS INTEGRITY MON-ITORING (RAIM)− A technique whereby a civilGNSS receiver/processor determines the integrity ofthe GNSS navigation signals without reference tosensors or non-DoD integrity systems other than thereceiver itself. This determination is achieved by aconsistency check among redundant pseudorangemeasurements.

RECEIVING CONTROLLER− A controller/facilityreceiving control of an aircraft from anothercontroller/facility.

RECEIVING FACILITY−(See RECEIVING CONTROLLER.)

RECONFORMANCE− The automated process ofbringing an aircraft’s Current Plan Trajectory intoconformance with its track.

REDUCE SPEED TO (SPEED)−(See SPEED ADJUSTMENT.)

REFINED HAZARD AREA (RHA)− Used by ATC.Airspace that is defined and distributed after a failureof a launch or reentry operation to provide a moreconcise depiction of the hazard location than aContingency Hazard Area.

(See AIRCRAFT HAZARD AREA.)(See CONTINGENCY HAZARD AREA.)(See TRANSITIONAL HAZARD AREA.)

REIL−(See RUNWAY END IDENTIFIER LIGHTS.)

RELEASE TIME− A departure time restrictionissued to a pilot by ATC (either directly or through anauthorized relay) when necessary to separate adeparting aircraft from other traffic.

(See ICAO term RELEASE TIME.)

RELEASE TIME [ICAO]− Time prior to which anaircraft should be given further clearance or prior towhich it should not proceed in case of radio failure.

REMOTE AIRPORT INFORMATION SERVICE(RAIS)− A temporary service provided by facilities,which are not located on the landing airport, but havecommunication capability and automated weatherreporting available to the pilot at the landing airport.

REMOTE COMMUNICATIONS AIR/GROUNDFACILITY− An unmanned VHF/UHF transmitter/receiver facility which is used to expand ARTCCair/ground communications coverage and to facilitatedirect contact between pilots and controllers. RCAGfacilities are sometimes not equipped with emergen-cy frequencies 121.5 MHz and 243.0 MHz.

(Refer to AIM.)

REMOTE COMMUNICATIONS OUTLET(RCO)− An unmanned communications facilityremotely controlled by air traffic personnel. RCOsserve FSSs. Remote Transmitter/Receivers (RTR)serve terminal ATC facilities. An RCO or RTR maybe UHF or VHF and will extend the communicationrange of the air traffic facility. There are severalclasses of RCOs and RTRs. The class is determinedby the number of transmitters or receivers. Classes Athrough G are used primarily for air/ground purposes.RCO and RTR class O facilities are nonprotectedoutlets subject to undetected and prolonged outages.RCO (O’s) and RTR (O’s) were established for theexpress purpose of providing ground-to-groundcommunications between air traffic control special-ists and pilots located at a satellite airport fordelivering en route clearances, issuing departureauthorizations, and acknowledging instrument flightrules cancellations or departure/landing times. As asecondary function, they may be used for advisorypurposes whenever the aircraft is below the coverageof the primary air/ground frequency.

REMOTE TRANSMITTER/RECEIVER (RTR)−(See REMOTE COMMUNICATIONS OUTLET.)

REPORT− Used to instruct pilots to advise ATC ofspecified information; e.g., “Report passing Hamil-ton VOR.”

REPORTING POINT− A geographical location inrelation to which the position of an aircraft isreported.

(See COMPULSORY REPORTING POINTS.)(See ICAO term REPORTING POINT.)(Refer to AIM.)



PCG R−5

REPORTING POINT [ICAO]− A specified geo-graphical location in relation to which the position ofan aircraft can be reported.

REQUEST FULL ROUTE CLEARANCE− Usedby pilots to request that the entire route of flight beread verbatim in an ATC clearance. Such requestshould be made to preclude receiving an ATCclearance based on the original filed flight plan whena filed IFR flight plan has been revised by the pilot,company, or operations prior to departure.

REQUIRED NAVIGATION PERFORMANCE(RNP)– A statement of the navigational performancenecessary for operation within a defined airspace.The following terms are commonly associated withRNP:

a. Required Navigation Performance Level orType (RNP-X). A value, in nautical miles (NM), fromthe intended horizontal position within which anaircraft would be at least 95-percent of the total flyingtime.

b. Advanced − Required Navigation Performance(A−RNP). A navigation specification based on RNPthat requires advanced functions such as scalableRNP, radius−to−fix (RF) legs, and tactical paralleloffsets. This sophisticated Navigation Specification(NavSpec) is designated by the abbreviation“A−RNP”.

c. Required Navigation Performance (RNP)Airspace. A generic term designating airspace,route(s), leg(s), operation(s), or procedure(s) whereminimum required navigational performance (RNP)have been established.

d. Actual Navigation Performance (ANP). Ameasure of the current estimated navigationalperformance. Also referred to as Estimated PositionError (EPE).

e. Estimated Position Error (EPE). A measure ofthe current estimated navigational performance. Alsoreferred to as Actual Navigation Performance (ANP).

f. Lateral Navigation (LNAV). A function of areanavigation (RNAV) equipment which calculates,displays, and provides lateral guidance to a profile orpath.

g. Vertical Navigation (VNAV). A function of areanavigation (RNAV) equipment which calculates,displays, and provides vertical guidance to a profileor path.

RESCUE COORDINATION CENTER (RCC)− Asearch and rescue (SAR) facility equipped andmanned to coordinate and control SAR operations inan area designated by the SAR plan. The U.S. CoastGuard and the U.S. Air Force have responsibility forthe operation of RCCs.

(See ICAO term RESCUE CO-ORDINATIONCENTRE.)

RESCUE CO-ORDINATION CENTRE [ICAO]− Aunit responsible for promoting efficient organizationof search and rescue service and for coordinating theconduct of search and rescue operations within asearch and rescue region.

RESOLUTION ADVISORY− A display indicationgiven to the pilot by the Traffic alert and CollisionAvoidance System (TCAS II) recommending amaneuver to increase vertical separation relative to anintruding aircraft. Positive, negative, and verticalspeed limit (VSL) advisories constitute the resolutionadvisories. A resolution advisory is also classified ascorrective or preventive.

RESTRICTED AREA−(See SPECIAL USE AIRSPACE.)(See ICAO term RESTRICTED AREA.)

RESTRICTED AREA [ICAO]− An airspace ofdefined dimensions, above the land areas or territorialwaters of a State, within which the flight of aircraftis restricted in accordance with certain specifiedconditions.

RESUME NORMAL SPEED− Used by ATC toadvise a pilot to resume an aircraft’s normal operatingspeed. It is issued to terminate a speed adjustmentwhere no published speed restrictions apply. It doesnot delete speed restrictions in published proceduresof upcoming segments of flight. This does not relievethe pilot of those speed restrictions that are applicableto 14 CFR Section 91.117.

RESUME OWN NAVIGATION− Used by ATC toadvise a pilot to resume his/her own navigationalresponsibility. It is issued after completion of a radarvector or when radar contact is lost while the aircraftis being radar vectored.

(See RADAR CONTACT LOST.)(See RADAR SERVICE TERMINATED.)

RESUME PUBLISHED SPEED− Used by ATC toadvise a pilot to resume published speed restrictionsthat are applicable to a SID, STAR, or otherinstrument procedure. It is issued to terminate a speed



PCG R−6

adjustment where speed restrictions are published ona charted procedure.

RHA−(See REFINED HAZARD AREA.)

RMI−(See RADIO MAGNETIC INDICATOR.)

RNAV−(See AREA NAVIGATION (RNAV).)

RNAV APPROACH− An instrument approachprocedure which relies on aircraft area navigationequipment for navigational guidance.

(See AREA NAVIGATION (RNAV).)(See INSTRUMENT APPROACHPROCEDURE.)

ROAD RECONNAISSANCE (RC)− Military activ-ity requiring navigation along roads, railroads, andrivers. Reconnaissance route/route segments areseldom along a straight line and normally require alateral route width of 10 NM to 30 NM and an altituderange of 500 feet to 10,000 feet AGL.

ROGER− I have received all of your lasttransmission. It should not be used to answer aquestion requiring a yes or a no answer.

(See AFFIRMATIVE.)(See NEGATIVE.)

ROLLOUT RVR−

(See VISIBILITY.)

ROTOR WASH− A phenomenon resulting from thevertical down wash of air generated by the mainrotor(s) of a helicopter.

ROUND−ROBIN FLIGHT PLAN− A single flightplan filed from the departure airport to anintermediary destination(s) and then returning to theoriginal departure airport.

ROUTE− A defined path, consisting of one or morecourses in a horizontal plane, which aircraft traverseover the surface of the earth.

(See AIRWAY.)(See JET ROUTE.)(See PUBLISHED ROUTE.)(See UNPUBLISHED ROUTE.)

ROUTE ACTION NOTIFICATION− EDST notifi-cation that a PAR/PDR/PDAR has been applied to theflight plan.

(See ATC PREFERRED ROUTENOTIFICATION.)


ROUTE SEGMENT− As used in Air Traffic Control,a part of a route that can be defined by twonavigational fixes, two NAVAIDs, or a fix and aNAVAID.

(See FIX.)(See ROUTE.)(See ICAO term ROUTE SEGMENT.)

ROUTE SEGMENT [ICAO]− A portion of a route tobe flown, as defined by two consecutive significantpoints specified in a flight plan.

RSA−(See RUNWAY SAFETY AREA.)

RTR−(See REMOTE TRANSMITTER/RECEIVER.)

RUNWAY− A defined rectangular area on a landairport prepared for the landing and takeoff run ofaircraft along its length. Runways are normallynumbered in relation to their magnetic directionrounded off to the nearest 10 degrees; e.g., Runway1, Runway 25.

(See PARALLEL RUNWAYS.)(See ICAO term RUNWAY.)

RUNWAY [ICAO]− A defined rectangular area on aland aerodrome prepared for the landing and takeoffof aircraft.

RUNWAY CENTERLINE LIGHTING−(See AIRPORT LIGHTING.)

RUNWAY CONDITION CODES (RwyCC)− Nu-merical readings, provided by airport operators, thatindicate runway surface contamination (for example,slush, ice, rain, etc.). These values range from “1”(poor) to “6” (dry) and must be included on the ATISwhen the reportable condition is less than 6 in any oneor more of the three runway zones (touchdown,midpoint, rollout).

RUNWAY CONDITION READING− Numericaldecelerometer readings relayed by air trafficcontrollers at USAF and certain civil bases for use bythe pilot in determining runway braking action.These readings are routinely relayed only to USAFand Air National Guard Aircraft.

(See BRAKING ACTION.)



PCG R−7

RUNWAY CONDITION REPORT (RwyCR)− Adata collection worksheet used by airport operatorsthat correlates the runway percentage of coveragealong with the depth and type of contaminant for thepurpose of creating a FICON NOTAM.

(See RUNWAY CONDITION CODES.)

RUNWAY END IDENTIFIER LIGHTS (REIL)−(See AIRPORT LIGHTING.)

RUNWAY ENTRANCE LIGHTS (REL)−An arrayof red lights which include the first light at the holdline followed by a series of evenly spaced lights to therunway edge aligned with the taxiway centerline, andone additional light at the runway centerline in linewith the last two lights before the runway edge.

RUNWAY GRADIENT− The average slope, mea-sured in percent, between two ends or points on arunway. Runway gradient is depicted on Governmentaerodrome sketches when total runway gradientexceeds 0.3%.

RUNWAY HEADING− The magnetic direction thatcorresponds with the runway centerline extended, notthe painted runway number. When cleared to “fly ormaintain runway heading,” pilots are expected to flyor maintain the heading that corresponds with theextended centerline of the departure runway. Driftcorrection shall not be applied; e.g., Runway 4, actualmagnetic heading of the runway centerline 044, fly044.

RUNWAY IN USE/ACTIVE RUNWAY/DUTYRUNWAY− Any runway or runways currently beingused for takeoff or landing. When multiple runwaysare used, they are all considered active runways. Inthe metering sense, a selectable adapted item whichspecifies the landing runway configuration ordirection of traffic flow. The adapted optimum flightplan from each transition fix to the vertex isdetermined by the runway configuration for arrivalmetering processing purposes.

RUNWAY LIGHTS−(See AIRPORT LIGHTING.)

RUNWAY MARKINGS−(See AIRPORT MARKING AIDS.)

RUNWAY OVERRUN− In military aviation exclu-sively, a stabilized or paved area beyond the end of arunway, of the same width as the runway plus

shoulders, centered on the extended runwaycenterline.

RUNWAY PROFILE DESCENT− An instrumentflight rules (IFR) air traffic control arrival procedureto a runway published for pilot use in graphic and/ortextual form and may be associated with a STAR.Runway Profile Descents provide routing and maydepict crossing altitudes, speed restrictions, andheadings to be flown from the en route structure to thepoint where the pilot will receive clearance for andexecute an instrument approach procedure. ARunway Profile Descent may apply to more than onerunway if so stated on the chart.

(Refer to AIM.)

RUNWAY SAFETY AREA− A defined surfacesurrounding the runway prepared, or suitable, forreducing the risk of damage to airplanes in the eventof an undershoot, overshoot, or excursion from therunway. The dimensions of the RSA vary and can bedetermined by using the criteria contained withinAC 150/5300-13, Airport Design, Chapter 3.Figure 3−1 in AC 150/5300-13 depicts the RSA. Thedesign standards dictate that the RSA shall be:

a. Cleared, graded, and have no potentiallyhazardous ruts, humps, depressions, or other surfacevariations;

b. Drained by grading or storm sewers to preventwater accumulation;

c. Capable, under dry conditions, of supportingsnow removal equipment, aircraft rescue andfirefighting equipment, and the occasional passage ofaircraft without causing structural damage to theaircraft; and,

d. Free of objects, except for objects that need tobe located in the runway safety area because of theirfunction. These objects shall be constructed on lowimpact resistant supports (frangible mounted struc-tures) to the lowest practical height with the frangiblepoint no higher than 3 inches above grade.

(Refer to AC 150/5300-13, Airport Design,Chapter 3.)

RUNWAY STATUS LIGHTS (RWSL) SYSTEM−The RWSL is a system of runway and taxiwaylighting to provide pilots increased situationalawareness by illuminating runway entry lights (REL)when the runway is unsafe for entry or crossing, andtake-off hold lights (THL) when the runway is unsafefor departure.



PCG R−8

RUNWAY TRANSITION−

a. Conventional STARs/SIDs. The portion of aSTAR/SID that serves a particular runway orrunways at an airport.

b. RNAV STARs/SIDs. Defines a path(s) fromthe common route to the final point(s) on a STAR. Fora SID, the common route that serves a particularrunway or runways at an airport.

RUNWAY USE PROGRAM− A noise abatementrunway selection plan designed to enhance noiseabatement efforts with regard to airport communitiesfor arriving and departing aircraft. These plans aredeveloped into runway use programs and apply to allturbojet aircraft 12,500 pounds or heavier; turbojetaircraft less than 12,500 pounds are included only ifthe airport proprietor determines that the aircraftcreates a noise problem. Runway use programs arecoordinated with FAA offices, and safety criteriaused in these programs are developed by the Office ofFlight Operations. Runway use programs are

administered by the Air Traffic Service as “Formal”or “Informal” programs.

a. Formal Runway Use Program− An approvednoise abatement program which is defined andacknowledged in a Letter of Understanding betweenFlight Operations, Air Traffic Service, the airportproprietor, and the users. Once established, participa-tion in the program is mandatory for aircraft operatorsand pilots as provided for in 14 CFR Section 91.129.

b. Informal Runway Use Program− An approvednoise abatement program which does not require aLetter of Understanding, and participation in theprogram is voluntary for aircraft operators/pilots.

RUNWAY VISUAL RANGE (RVR)−(See VISIBILITY.)

RwyCC−(See RUNWAY CONDITION CODES.)

RwyCR−(See RUNWAY CONDITION REPORT.)



PCG S−1

SSAA−

(See SPECIAL ACTIVITY AIRSPACE.)

SAFETY ALERT− A safety alert issued by ATC toaircraft under their control if ATC is aware the aircraftis at an altitude which, in the controller’s judgment,places the aircraft in unsafe proximity to terrain,obstructions, or other aircraft. The controller maydiscontinue the issuance of further alerts if the pilotadvises he/she is taking action to correct the situationor has the other aircraft in sight.

a. Terrain/Obstruction Alert− A safety alert issuedby ATC to aircraft under their control if ATC is awarethe aircraft is at an altitude which, in the controller’sjudgment, places the aircraft in unsafe proximity toterrain/obstructions; e.g., “Low Altitude Alert, checkyour altitude immediately.”

b. Aircraft Conflict Alert− A safety alert issued byATC to aircraft under their control if ATC is aware ofan aircraft that is not under their control at an altitudewhich, in the controller’s judgment, places bothaircraft in unsafe proximity to each other. With thealert, ATC will offer the pilot an alternate course ofaction when feasible; e.g., “Traffic Alert, advise youturn right heading zero niner zero or climb to eightthousand immediately.”

Note: The issuance of a safety alert is contingentupon the capability of the controller to have anawareness of an unsafe condition. The course ofaction provided will be predicated on other trafficunder ATC control. Once the alert is issued, it issolely the pilot’s prerogative to determine whatcourse of action, if any, he/she will take.

SAFETY LOGIC SYSTEM− A software enhance-ment to ASDE−3, ASDE−X, and ASSC, that predictsthe path of aircraft landing and/or departing, and/orvehicular movements on runways. Visual and auralalarms are activated when the safety logic projects apotential collision. The Airport Movement AreaSafety System (AMASS) is a safety logic systemenhancement to the ASDE−3. The Safety LogicSystem for ASDE−X and ASSC is an integral part ofthe software program.

SAFETY LOGIC SYSTEM ALERTS−

a. ALERT− An actual situation involving two realsafety logic tracks (aircraft/aircraft, aircraft/vehicle,

or aircraft/other tangible object) that safety logic haspredicted will result in an imminent collision, basedupon the current set of Safety Logic parameters.

b. FALSE ALERT−1. Alerts generated by one or more false

surface−radar targets that the system has interpretedas real tracks and placed into safety logic.

2. Alerts in which the safety logic software didnot perform correctly, based upon the designspecifications and the current set of Safety Logicparameters.

3. The alert is generated by surface radar targetscaused by moderate or greater precipitation.

c. NUISANCE ALERT− An alert in which one ormore of the following is true:

1. The alert is generated by a known situationthat is not considered an unsafe operation, such asLAHSO or other approved operations.

2. The alert is generated by inaccurate secon-dary radar data received by the Safety Logic System.

3. One or more of the aircraft involved in thealert is not intending to use a runway (for example,helicopter, pipeline patrol, non−Mode C overflight,etc.).

d. VALID NON−ALERT− A situation in whichthe safety logic software correctly determines that analert is not required, based upon the designspecifications and the current set of Safety Logicparameters.

e. INVALID NON−ALERT− A situation in whichthe safety logic software did not issue an alert whenan alert was required, based upon the designspecifications.

SAIL BACK− A maneuver during high windconditions (usually with power off) where float planemovement is controlled by water rudders/openingand closing cabin doors.

SAME DIRECTION AIRCRAFT− Aircraft areoperating in the same direction when:

a. They are following the same track in the samedirection; or

b. Their tracks are parallel and the aircraft areflying in the same direction; or

c. Their tracks intersect at an angle of less than 45degrees.


PCG S−2

SAR−

(See SEARCH AND RESCUE.)

SATELLITE−BASED AUGMENTATION SYS-TEM (SBAS) − A wide coverage augmentationsystem in which the user receives augmentationinformation from a satellite−based transmitter.

(See WIDE−AREA AUGMENTATION SYSTEM(WAAS.)

SAY AGAIN− Used to request a repeat of the lasttransmission. Usually specifies transmission orportion thereof not understood or received; e.g., “Sayagain all after ABRAM VOR.”

SAY ALTITUDE− Used by ATC to ascertain anaircraft’s specific altitude/flight level. When theaircraft is climbing or descending, the pilot shouldstate the indicated altitude rounded to the nearest 100feet.

SAY HEADING− Used by ATC to request an aircraftheading. The pilot should state the actual heading ofthe aircraft.

SCHEDULED TIME OF ARRIVAL (STA)− A STAis the desired time that an aircraft should cross acertain point (landing or metering fix). It takes othertraffic and airspace configuration into account. ASTA time shows the results of the TBFM schedulerthat has calculated an arrival time according toparameters such as optimized spacing, aircraftperformance, and weather.

SDF−(See SIMPLIFIED DIRECTIONAL FACILITY.)

SEA LANE− A designated portion of water outlinedby visual surface markers for and intended to be usedby aircraft designed to operate on water.

SEARCH AND RESCUE− A service which seeksmissing aircraft and assists those found to be in needof assistance. It is a cooperative effort using thefacilities and services of available Federal, state andlocal agencies. The U.S. Coast Guard is responsiblefor coordination of search and rescue for the MaritimeRegion, and the U.S. Air Force is responsible forsearch and rescue for the Inland Region. Informationpertinent to search and rescue should be passedthrough any air traffic facility or be transmitted

directly to the Rescue Coordination Center bytelephone.

(See FLIGHT SERVICE STATION.)(See RESCUE COORDINATION CENTER.)(Refer to AIM.)

SEARCH AND RESCUE FACILITY− A facilityresponsible for maintaining and operating a searchand rescue (SAR) service to render aid to persons andproperty in distress. It is any SAR unit, station, NET,or other operational activity which can be usefullyemployed during an SAR Mission; e.g., a Civil AirPatrol Wing, or a Coast Guard Station.

(See SEARCH AND RESCUE.)

SECNOT−(See SECURITY NOTICE.)

SECONDARY RADAR TARGET− A target derivedfrom a transponder return presented on a radardisplay.

SECTIONAL AERONAUTICAL CHARTS−(See AERONAUTICAL CHART.)

SECTOR LIST DROP INTERVAL− A parameternumber of minutes after the meter fix time whenarrival aircraft will be deleted from the arrival sectorlist.

SECURITY NOTICE (SECNOT) − A SECNOT is arequest originated by the Air Traffic SecurityCoordinator (ATSC) for an extensive communica-tions search for aircraft involved, or suspected ofbeing involved, in a security violation, or areconsidered a security risk. A SECNOT will includethe aircraft identification, search area, and expirationtime. The search area, as defined by the ATSC, couldbe a single airport, multiple airports, a radius of anairport or fix, or a route of flight. Once the expirationtime has been reached, the SECNOT is considered tobe canceled.

SECURITY SERVICES AIRSPACE − Areasestablished through the regulatory process or byNOTAM, issued by the Administrator under title 14,CFR, sections 99.7, 91.141, and 91.139, whichspecify that ATC security services are required; i.e.,ADIZ or temporary flight rules areas.

SEE AND AVOID− When weather conditionspermit, pilots operating IFR or VFR are required toobserve and maneuver to avoid other aircraft.Right-of-way rules are contained in 14 CFR Part 91.

SEGMENTED CIRCLE− A system of visualindicators designed to provide traffic pattern


PCG S−3

information at airports without operating controltowers.

(Refer to AIM.)

SEGMENTS OF AN INSTRUMENT APPROACHPROCEDURE− An instrument approach proceduremay have as many as four separate segmentsdepending on how the approach procedure isstructured.

a. Initial Approach− The segment between theinitial approach fix and the intermediate fix or thepoint where the aircraft is established on theintermediate course or final approach course.

(See ICAO term INITIAL APPROACHSEGMENT.)

b. Intermediate Approach− The segment betweenthe intermediate fix or point and the final approachfix.

(See ICAO term INTERMEDIATE APPROACHSEGMENT.)

c. Final Approach− The segment between the finalapproach fix or point and the runway, airport, ormissed approach point.

(See ICAO term FINAL APPROACH SEGMENT.)

d. Missed Approach− The segment between themissed approach point or the point of arrival atdecision height and the missed approach fix at theprescribed altitude.

(Refer to 14 CFR Part 97.)(See ICAO term MISSED APPROACHPROCEDURE.)

SEPARATION− In air traffic control, the spacing ofaircraft to achieve their safe and orderly movement inflight and while landing and taking off.

(See SEPARATION MINIMA.)(See ICAO term SEPARATION.)

SEPARATION [ICAO]− Spacing between aircraft,levels or tracks.

SEPARATION MINIMA− The minimum longitudi-nal, lateral, or vertical distances by which aircraft arespaced through the application of air traffic controlprocedures.

(See SEPARATION.)

SERVICE− A generic term that designates functionsor assistance available from or rendered by air trafficcontrol. For example, Class C service would denotethe ATC services provided within a Class C airspacearea.

SEVERE WEATHER AVOIDANCE PLAN(SWAP)− An approved plan to minimize the affect ofsevere weather on traffic flows in impacted terminaland/or ARTCC areas. A SWAP is normallyimplemented to provide the least disruption to theATC system when flight through portions of airspaceis difficult or impossible due to severe weather.

SEVERE WEATHER FORECAST ALERTS−Preliminary messages issued in order to alert usersthat a Severe Weather Watch Bulletin (WW) is beingissued. These messages define areas of possiblesevere thunderstorms or tornado activity. Themessages are unscheduled and issued as required bythe Storm Prediction Center (SPC) at Norman,Oklahoma.

(See AIRMET.)(See CONVECTIVE SIGMET.)(See CWA.)(See SIGMET.)

SFA−(See SINGLE FREQUENCY APPROACH.)

SFO−(See SIMULATED FLAMEOUT.)

SHF−(See SUPER HIGH FREQUENCY.)

SHORT RANGE CLEARANCE− A clearanceissued to a departing IFR flight which authorizes IFRflight to a specific fix short of the destination whileair traffic control facilities are coordinating andobtaining the complete clearance.

SHORT TAKEOFF AND LANDING AIRCRAFT(STOL)− An aircraft which, at some weight within itsapproved operating weight, is capable of operatingfrom a runway in compliance with the applicableSTOL characteristics, airworthiness, operations,noise, and pollution standards.

(See VERTICAL TAKEOFF AND LANDINGAIRCRAFT.)

SIAP−(See STANDARD INSTRUMENT APPROACHPROCEDURE.)

SID−(See STANDARD INSTRUMENT DEPARTURE.)

SIDESTEP MANEUVER− A visual maneuveraccomplished by a pilot at the completion of aninstrument approach to permit a straight-in landingon a parallel runway not more than 1,200 feet to either


PCG S−4

side of the runway to which the instrument approachwas conducted.

(Refer to AIM.)

SIGMET− A weather advisory issued concerningweather significant to the safety of all aircraft.SIGMET advisories cover severe and extremeturbulence, severe icing, and widespread dust orsandstorms that reduce visibility to less than 3 miles.

(See AIRMET.)(See AWW.)(See CONVECTIVE SIGMET.)(See CWA.)(See ICAO term SIGMET INFORMATION.)(Refer to AIM.)

SIGMET INFORMATION [ICAO]− Informationissued by a meteorological watch office concerningthe occurrence or expected occurrence of specifieden-route weather phenomena which may affect thesafety of aircraft operations.

SIGNIFICANT METEOROLOGICAL INFOR-MATION−

(See SIGMET.)

SIGNIFICANT POINT− A point, whether a namedintersection, a NAVAID, a fix derived from aNAVAID(s), or geographical coordinate expressed indegrees of latitude and longitude, which isestablished for the purpose of providing separation,as a reporting point, or to delineate a route of flight.

SIMPLIFIED DIRECTIONAL FACILITY (SDF)−A NAVAID used for nonprecision instrumentapproaches. The final approach course is similar tothat of an ILS localizer except that the SDF coursemay be offset from the runway, generally not morethan 3 degrees, and the course may be wider than thelocalizer, resulting in a lower degree of accuracy.

(Refer to AIM.)

SIMULATED FLAMEOUT− A practice approachby a jet aircraft (normally military) at idle thrust to arunway. The approach may start at a runway (highkey) and may continue on a relatively high and widedownwind leg with a continuous turn to final. Itterminates in landing or low approach. The purposeof this approach is to simulate a flameout.

(See FLAMEOUT.)

SIMULTANEOUS CLOSE PARALLEL AP-PROACHES− A simultaneous, independent

approach operation permitting ILS/RNAV/GLSapproaches to airports having parallel runwaysseparated by at least 3,000 feet and less than4,300−feet between centerlines. Aircraft are permit-ted to pass each other during these simultaneousoperations. Integral parts of a total system are radar,NTZ monitoring with enhanced FMA color displaysthat include aural and visual alerts and predictiveaircraft position software, communications override,ATC procedures, an Attention All Users Page(AAUP), PRM in the approach name, andappropriate ground based and airborne equipment.High update rate surveillance sensor required forcertain runway or approach course separations.

SIMULTANEOUS (CONVERGING) DEPEND-ENT APPROACHES- An approach operationpermitting ILS/RNAV/GLS approaches to runwaysor missed approach courses that intersect whererequired minimum spacing between the aircraft oneach final approach course is required.

SIMULTANEOUS (CONVERGING) INDEPEND-ENT APPROACHES- An approach operationpermitting ILS/RNAV/GLS approaches to non-par-allel runways where approach procedure designmaintains the required aircraft spacing throughoutthe approach and missed approach and hence theoperations may be conducted independently.

SIMULTANEOUS ILS APPROACHES− Anapproach system permitting simultaneous ILSapproaches to airports having parallel runwaysseparated by at least 4,300 feet between centerlines.Integral parts of a total system are ILS, radar,communications, ATC procedures, and appropriateairborne equipment.

(See PARALLEL RUNWAYS.)(Refer to AIM.)

SIMULTANEOUS OFFSET INSTRUMENTAPPROACH (SOIA)− An instrument landingsystem comprised of an ILS PRM, RNAV PRM orGLS PRM approach to one runway and an offsetLDA PRM with glideslope or an RNAV PRM orGLS PRM approach utilizing vertical guidance toanother where parallel runway spaced less than 3,000feet and at least 750 feet apart. The approach coursesconverge by 2.5 to 3 degrees. Simultaneous closeparallel PRM approach procedures apply up to thepoint where the approach course separation becomes3,000 feet, at the offset MAP. From the offset MAP


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to the runway threshold, visual separation by theaircraft conducting the offset approach is utilized.

(Refer to AIM)

SIMULTANEOUS (PARALLEL) DEPENDENTAPPROACHES- An approach operation permittingILS/RNAV/GLS approaches to adjacent parallelrunways where prescribed diagonal spacing must bemaintained. Aircraft are not permitted to pass eachother during simultaneous dependent operations.Integral parts of a total system ATC procedures, andappropriate airborne and ground based equipment.

SINGLE DIRECTION ROUTES− Preferred IFRRoutes which are sometimes depicted on highaltitude en route charts and which are normally flownin one direction only.

(See PREFERRED IFR ROUTES.)(Refer to CHART SUPPLEMENT U.S.)

SINGLE FREQUENCY APPROACH− A serviceprovided under a letter of agreement to militarysingle-piloted turbojet aircraft which permits use ofa single UHF frequency during approach for landing.Pilots will not normally be required to changefrequency from the beginning of the approach totouchdown except that pilots conducting an en routedescent are required to change frequency whencontrol is transferred from the air route traffic controlcenter to the terminal facility. The abbreviation“SFA” in the DOD FLIP IFR Supplement under“Communications” indicates this service is availableat an aerodrome.

SINGLE-PILOTED AIRCRAFT− A militaryturbojet aircraft possessing one set of flight controls,tandem cockpits, or two sets of flight controls butoperated by one pilot is considered single-piloted byATC when determining the appropriate air trafficservice to be applied.

(See SINGLE FREQUENCY APPROACH.)

SKYSPOTTER− A pilot who has receivedspecialized training in observing and reportinginflight weather phenomena.

SLASH− A radar beacon reply displayed as anelongated target.

SLDI−(See SECTOR LIST DROP INTERVAL.)

SLOT TIME−(See METER FIX TIME/SLOT TIME.)

SLOW TAXI− To taxi a float plane at low power orlow RPM.

SN−(See SYSTEM STRATEGIC NAVIGATION.)

SPACE−BASED ADS−B (SBA)− A constellation ofsatellites that receives ADS−B Out broadcasts andrelays that information to the appropriate surveil-lance facility. The currently deployed SBA system isonly capable of receiving broadcasts from 1090ES−equipped aircraft, and not from those equipped withonly a universal access transceiver (UAT). Also,aircraft with a top−of−fuselage−mounted transponderantenna (required for TCAS II installations) will bebetter received by SBA, especially at latitudes below45 degrees.



SPEAK SLOWER− Used in verbal communicationsas a request to reduce speech rate.

SPECIAL ACTIVITY AIRSPACE (SAA)− Anyairspace with defined dimensions within the NationalAirspace System wherein limitations may beimposed upon aircraft operations. This airspace maybe restricted areas, prohibited areas, militaryoperations areas, air ATC assigned airspace, and anyother designated airspace areas. The dimensions ofthis airspace are programmed into EDST and can bedesignated as either active or inactive by screen entry.Aircraft trajectories are constantly tested against thedimensions of active areas and alerts issued to theapplicable sectors when violations are predicted.


SPECIAL AIR TRAFFIC RULES (SATR)− Rulesthat govern procedures for conducting flights incertain areas listed in 14 CFR Part 93. The term“SATR” is used in the United States to describe therules for operations in specific areas designated in theCode of Federal Regulations.


SPECIAL EMERGENCY− A condition of air piracyor other hostile act by a person(s) aboard an aircraftwhich threatens the safety of the aircraft or itspassengers.

SPECIAL FLIGHT RULES AREA (SFRA)− Anarea in the NAS, described in 14 CFR Part 93,wherein the flight of aircraft is subject to special



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traffic rules, unless otherwise authorized by air trafficcontrol. Not all areas listed in 14 CFR Part 93 aredesignated SFRA, but special air traffic rules apply toall areas described in 14 CFR Part 93.

SPECIAL INSTRUMENT APPROACH PROCE-DURE−

(See INSTRUMENT APPROACH PROCEDURE.)

SPECIAL USE AIRSPACE− Airspace of defineddimensions identified by an area on the surface of theearth wherein activities must be confined because oftheir nature and/or wherein limitations may beimposed upon aircraft operations that are not a part ofthose activities. Types of special use airspace are:

a. Alert Area− Airspace which may contain a highvolume of pilot training activities or an unusual typeof aerial activity, neither of which is hazardous toaircraft. Alert Areas are depicted on aeronauticalcharts for the information of nonparticipating pilots.All activities within an Alert Area are conducted inaccordance with Federal Aviation Regulations, andpilots of participating aircraft as well as pilotstransiting the area are equally responsible forcollision avoidance.

b. Controlled Firing Area− Airspace whereinactivities are conducted under conditions socontrolled as to eliminate hazards to nonparticipatingaircraft and to ensure the safety of persons andproperty on the ground.

c. Military Operations Area (MOA)− Permanentand temporary MOAs are airspace establishedoutside of Class A airspace area to separate orsegregate certain nonhazardous military activitiesfrom IFR traffic and to identify for VFR traffic wherethese activities are conducted. Permanent MOAs aredepicted on Sectional Aeronautical, VFR TerminalArea, and applicable En Route Low Altitude Charts.

Note: Temporary MOAs are not charted.

(Refer to AIM.)

d. Prohibited Area− Airspace designated under14 CFR Part 73 within which no person may operatean aircraft without the permission of the usingagency.

(Refer to AIM.)(Refer to En Route Charts.)

e. Restricted Area− Permanent and temporaryrestricted areas are airspace designated under 14 CFRPart 73, within which the flight of aircraft, while notwholly prohibited, is subject to restriction. Most

restricted areas are designated joint use and IFR/VFRoperations in the area may be authorized by thecontrolling ATC facility when it is not being utilizedby the using agency. Permanent restricted areas aredepicted on Sectional Aeronautical, VFR TerminalArea, and applicable En Route charts. Where jointuse is authorized, the name of the ATC controllingfacility is also shown.

Note: Temporary restricted areas are not charted.


f. Warning Area− A warning area is airspace ofdefined dimensions extending from 3 nautical milesoutward from the coast of the United States, thatcontains activity that may be hazardous tononparticipating aircraft. The purpose of suchwarning area is to warn nonparticipating pilots of thepotential danger. A warning area may be located overdomestic or international waters or both.

SPECIAL VFR CONDITIONS− Meteorologicalconditions that are less than those required for basicVFR flight in Class B, C, D, or E surface areas andin which some aircraft are permitted flight undervisual flight rules.

(See SPECIAL VFR OPERATIONS.)(Refer to 14 CFR Part 91.)

SPECIAL VFR FLIGHT [ICAO]− A VFR flightcleared by air traffic control to operate within ClassB, C, D, and E surface areas in metrologicalconditions below VMC.

SPECIAL VFR OPERATIONS− Aircraft operatingin accordance with clearances within Class B, C, D,and E surface areas in weather conditions less than thebasic VFR weather minima. Such operations must berequested by the pilot and approved by ATC.

(See SPECIAL VFR CONDITIONS.)(See ICAO term SPECIAL VFR FLIGHT.)

SPEED−(See AIRSPEED.)(See GROUND SPEED.)

SPEED ADJUSTMENT− An ATC procedure used torequest pilots to adjust aircraft speed to a specificvalue for the purpose of providing desired spacing.Pilots are expected to maintain a speed of plus orminus 10 knots or 0.02 Mach number of the specifiedspeed. Examples of speed adjustments are:

a. “Increase/reduce speed to Mach point(number).”



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b. “Increase/reduce speed to (speed in knots)” or“Increase/reduce speed (number of knots) knots.”

SPEED BRAKES− Moveable aerodynamic deviceson aircraft that reduce airspeed during descent andlanding.

SPEED SEGMENTS− Portions of the arrival routebetween the transition point and the vertex along theoptimum flight path for which speeds and altitudesare specified. There is one set of arrival speedsegments adapted from each transition point to eachvertex. Each set may contain up to six segments.

SPOOFING− Denotes emissions of GNSS−likesignals that may be acquired and tracked incombination with or instead of the intended signalsby civil receivers. The onset of spoofing effects canbe instantaneous or delayed, and effects can persistafter the spoofing has ended. Spoofing can result infalse and potentially confusing, or hazardouslymisleading, position, navigation, and/or date/timeinformation in addition to loss of GNSS use.

SQUAWK (Mode, Code, Function)− Used by ATCto instruct a pilot to activate the aircraft transponderand ADS−B Out with altitude reporting enabled, or(military) to activate only specific modes, codes, orfunctions. Examples: “Squawk five seven zeroseven;” “Squawk three/alpha, two one zero five.”

(See TRANSPONDER.)

STA−(See SCHEDULED TIME OF ARRIVAL.)

STAGING/QUEUING− The placement, integration,and segregation of departure aircraft in designatedmovement areas of an airport by departure fix, EDCT,and/or restriction.

STAND BY− Means the controller or pilot mustpause for a few seconds, usually to attend to otherduties of a higher priority. Also means to wait as in“stand by for clearance.” The caller shouldreestablish contact if a delay is lengthy. “Stand by” isnot an approval or denial.

STANDARD INSTRUMENT APPROACH PRO-CEDURE (SIAP)−

(See INSTRUMENT APPROACH PROCEDURE.)

STANDARD INSTRUMENT DEPARTURE (SID)−A preplanned instrument flight rule (IFR) air trafficcontrol (ATC) departure procedure printed forpilot/controller use in graphic form to provide

obstacle clearance and a transition from the terminalarea to the appropriate en route structure. SIDs areprimarily designed for system enhancement toexpedite traffic flow and to reduce pilot/controllerworkload. ATC clearance must always be receivedprior to flying a SID.


(See OBSTACLE DEPARTURE PROCEDURE.)(Refer to AIM.)

STANDARD RATE TURN− A turn of three degreesper second.

STANDARD TERMINAL ARRIVAL (STAR)− Apreplanned instrument flight rule (IFR) air trafficcontrol arrival procedure published for pilot use ingraphic and/or textual form. STARs providetransition from the en route structure to an outer fixor an instrument approach fix/arrival waypoint in theterminal area.

STANDARD TERMINAL ARRIVAL CHARTS−(See AERONAUTICAL CHART.)

STANDARD TERMINAL AUTOMATION RE-PLACEMENT SYSTEM (STARS)−

(See DTAS.)

STAR−(See STANDARD TERMINAL ARRIVAL.)

STATE AIRCRAFT− Aircraft used in military,customs and police service, in the exclusive serviceof any government or of any political subdivisionthereof, including the government of any state,territory, or possession of the United States or theDistrict of Columbia, but not including anygovernment-owned aircraft engaged in carryingpersons or property for commercial purposes.

STATIC RESTRICTIONS− Those restrictions thatare usually not subject to change, fixed, in place,and/or published.

STATIONARY RESERVATIONS− Altitudereservations which encompass activities in a fixedarea. Stationary reservations may include activities,such as special tests of weapons systems orequipment, certain U.S. Navy carrier, fleet, andanti-submarine operations, rocket, missile and droneoperations, and certain aerial refueling or similaroperations.

STEP TAXI− To taxi a float plane at full power orhigh RPM.



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STEP TURN− A maneuver used to put a float planein a planing configuration prior to entering an activesea lane for takeoff. The STEP TURN maneuvershould only be used upon pilot request.

STEPDOWN FIX− A fix permitting additionaldescent within a segment of an instrument approachprocedure by identifying a point at which acontrolling obstacle has been safely overflown.

STEREO ROUTE− A routinely used route of flightestablished by users and ARTCCs identified by acoded name; e.g., ALPHA 2. These routes minimizeflight plan handling and communications.

STOL AIRCRAFT−(See SHORT TAKEOFF AND LANDINGAIRCRAFT.)

STOP ALTITUDE SQUAWK− Used by ATC toinstruct a pilot to turn off the automatic altitudereporting feature of the aircraft transponder andADS−B Out. It is issued when a verbally reportedaltitude varies by 300 feet or more from the automaticaltitude report.

(See ALTITUDE READOUT.)(See TRANSPONDER.)

STOP AND GO− A procedure wherein an aircraftwill land, make a complete stop on the runway, andthen commence a takeoff from that point.

(See LOW APPROACH.)(See OPTION APPROACH.)

STOP BURST−(See STOP STREAM.)

STOP BUZZER−(See STOP STREAM.)

STOP SQUAWK (Mode or Code)− Used by ATC toinstruct a pilot to stop transponder and ADS−Btransmissions, or to turn off only specified functionsof the aircraft transponder (military).

(See STOP ALTITUDE SQUAWK.)(See TRANSPONDER.)

STOP STREAM− Used by ATC to request a pilot tosuspend electronic attack activity.

(See JAMMING.)

STOPOVER FLIGHT PLAN− A flight plan formatwhich permits in a single submission the filing of asequence of flight plans through interim full-stopdestinations to a final destination.

STOPWAY− An area beyond the takeoff runway noless wide than the runway and centered upon theextended centerline of the runway, able to support theairplane during an aborted takeoff, without causingstructural damage to the airplane, and designated bythe airport authorities for use in decelerating theairplane during an aborted takeoff.

STRAIGHT-IN APPROACH IFR− An instrumentapproach wherein final approach is begun withoutfirst having executed a procedure turn, notnecessarily completed with a straight-in landing ormade to straight-in landing minimums.

(See LANDING MINIMUMS.)(See STRAIGHT-IN APPROACH VFR.)(See STRAIGHT-IN LANDING.)

STRAIGHT-IN APPROACH VFR− Entry into thetraffic pattern by interception of the extended runwaycenterline (final approach course) without executingany other portion of the traffic pattern.


STRAIGHT-IN LANDING− A landing made on arunway aligned within 30� of the final approachcourse following completion of an instrumentapproach.

(See STRAIGHT-IN APPROACH IFR.)

STRAIGHT-IN LANDING MINIMUMS−(See LANDING MINIMUMS.)

STRAIGHT-IN MINIMUMS−(See STRAIGHT-IN LANDING MINIMUMS.)

STRATEGIC PLANNING− Planning wherebysolutions are sought to resolve potential conflicts.

SUBSTITUTE ROUTE− A route assigned to pilotswhen any part of an airway or route is unusablebecause of NAVAID status. These routes consist of:

a. Substitute routes which are shown on U.S.Government charts.

b. Routes defined by ATC as specific NAVAIDradials or courses.

c. Routes defined by ATC as direct to or betweenNAVAIDs.

SUNSET AND SUNRISE− The mean solar times ofsunset and sunrise as published in the NauticalAlmanac, converted to local standard time for thelocality concerned. Within Alaska, the end of eveningcivil twilight and the beginning of morning civiltwilight, as defined for each locality.

SUPPLEMENTAL WEATHER SERVICE LOCA-TION− Airport facilities staffed with contract



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personnel who take weather observations andprovide current local weather to pilots via telephoneor radio. (All other services are provided by the parentFSS.)

SUPPS− Refers to ICAO Document 7030 RegionalSupplementary Procedures. SUPPS containprocedures for each ICAO Region which are uniqueto that Region and are not covered in the worldwideprovisions identified in the ICAO Air NavigationPlan. Procedures contained in Chapter 8 are based inpart on those published in SUPPS.

SURFACE AREA− The airspace contained by thelateral boundary of the Class B, C, D, or E airspacedesignated for an airport that begins at the surface andextends upward.

SURPIC− A description of surface vessels in the areaof a Search and Rescue incident including theirpredicted positions and their characteristics.

(Refer to FAA Order JO 7110.65, Para 10−6−4,INFLIGHT CONTINGENCIES.)

SURVEILLANCE APPROACH− An instrumentapproach wherein the air traffic controller issuesinstructions, for pilot compliance, based on aircraftposition in relation to the final approach course(azimuth), and the distance (range) from the end ofthe runway as displayed on the controller’s radarscope. The controller will provide recommendedaltitudes on final approach if requested by the pilot.

(Refer to AIM.)

SWAP−(See SEVERE WEATHER AVOIDANCE PLAN.)

SWSL−(See SUPPLEMENTAL WEATHER SERVICELOCATION.)

SYSTEM STRATEGIC NAVIGATION− Militaryactivity accomplished by navigating along apreplanned route using internal aircraft systems tomaintain a desired track. This activity normallyrequires a lateral route width of 10 NM and altituderange of 1,000 feet to 6,000 feet AGL with some routesegments that permit terrain following.



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TTACAN−

(See TACTICAL AIR NAVIGATION.)

TACAN-ONLY AIRCRAFT− An aircraft, normallymilitary, possessing TACAN with DME but no VORnavigational system capability. Clearances mustspecify TACAN or VORTAC fixes and approaches.

TACTICAL AIR NAVIGATION (TCAN)− Anultra-high frequency electronic rho-theta air naviga-tion aid which provides suitably equipped aircraft acontinuous indication of bearing and distance to theTACAN station.

(See VORTAC.)(Refer to AIM.)

TAILWIND− Any wind more than 90 degrees to thelongitudinal axis of the runway. The magneticdirection of the runway shall be used as the basis fordetermining the longitudinal axis.

TAKEOFF AREA−(See LANDING AREA.)

TAKEOFF DISTANCE AVAILABLE (TODA)– Thetakeoff run available plus the length of any remainingrunway or clearway beyond the far end of the takeoffrun available.

(See ICAO term TAKEOFF DISTANCEAVAILABLE.)

TAKEOFF DISTANCE AVAILABLE [ICAO]− Thelength of the takeoff run available plus the length ofthe clearway, if provided.

TAKEOFF HOLD LIGHTS (THL)– The THLsystem is composed of in-pavement lighting in adouble, longitudinal row of lights aligned either sideof the runway centerline. The lights are focusedtoward the arrival end of the runway at the “line upand wait” point, and they extend for 1,500 feet infront of the holding aircraft. Illuminated red lightsindicate to an aircraft in position for takeoff or rollingthat it is unsafe to takeoff because the runway isoccupied or about to be occupied by an aircraft orvehicle.

TAKEOFF ROLL − The process whereby an aircraftis aligned with the runway centerline and the aircraftis moving with the intent to take off. For helicopters,

this pertains to the act of becoming airborne afterdeparting a takeoff area.

TAKEOFF RUN AVAILABLE (TORA) – Therunway length declared available and suitable for theground run of an airplane taking off.

(See ICAO term TAKEOFF RUN AVAILABLE.)

TAKEOFF RUN AVAILABLE [ICAO]− The lengthof runway declared available and suitable for theground run of an aeroplane take-off.

TARGET− The indication shown on a displayresulting from a primary radar return, a radar beaconreply, or an ADS−B report. The specific targetsymbol presented to ATC may vary based on thesurveillance source and automation platform.

(See ASSOCIATED.)(See DIGITAL TARGET.)(See DIGITIZED RADAR TARGET.)(See FUSED TARGET.)(See PRIMARY RADAR TARGET.)(See RADAR.)(See SECONDARY RADAR TARGET.)(See ICAO term TARGET.)(See UNASSOCIATED.)

TARGET [ICAO]− In radar:a. Generally, any discrete object which reflects or

retransmits energy back to the radar equipment.b. Specifically, an object of radar search or

surveillance.

TARGET RESOLUTION− A process to ensure thatcorrelated radar targets do not touch. Targetresolution must be applied as follows:

a. Between the edges of two primary targets or theedges of the ASR-9/11 primary target symbol.

b. Between the end of the beacon control slash andthe edge of a primary target.

c. Between the ends of two beacon control slashes.Note 1: Mandatory traffic advisories and safetyalerts must be issued when this procedure is used.

Note 2: This procedure must not be used whenutilizing mosaic radar systems or multi−sensormode.

TARGET SYMBOL−(See TARGET.)(See ICAO term TARGET.)



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TARMAC DELAY− The holding of an aircraft on theground either before departure or after landing withno opportunity for its passengers to deplane.

TARMAC DELAY AIRCRAFT− An aircraft whosepilot−in−command has requested to taxi to the ramp,gate, or alternate deplaning area to comply with theThree−hour Tarmac Rule.

TARMAC DELAY REQUEST− A request by thepilot−in−command to taxi to the ramp, gate, oralternate deplaning location to comply with theThree−hour Tarmac Rule.

TAS−(See TERMINAL AUTOMATION SYSTEMS.)

TAWS−(See TERRAIN AWARENESS WARNINGSYSTEM.)

TAXI− The movement of an airplane under its ownpower on the surface of an airport (14 CFRSection 135.100 [Note]). Also, it describes thesurface movement of helicopters equipped withwheels.

(See AIR TAXI.)(See HOVER TAXI.)(Refer to 14 CFR Section 135.100.)(Refer to AIM.)

TAXI PATTERNS− Patterns established to illustratethe desired flow of ground traffic for the differentrunways or airport areas available for use.

TCAS−(See TRAFFIC ALERT AND COLLISIONAVOIDANCE SYSTEM.)

TCH−(See THRESHOLD CROSSING HEIGHT.)

TCLT−(See TENTATIVE CALCULATED LANDINGTIME.)

TDLS−(See TERMINAL DATA LINK SYSTEM.)

TDZE−(See TOUCHDOWN ZONE ELEVATION.)

TELEPHONE INFORMATION BRIEFING SER-VICE− A continuous telephone recording ofmeteorological and/or aeronautical information.

(Refer to AIM.)

TEMPORARY FLIGHT RESTRICTION (TFR)− ATFR is a regulatory action issued by the FAA via theU.S. NOTAM System, under the authority of UnitedStates Code, Title 49. TFRs are issued within thesovereign airspace of the United States and itsterritories to restrict certain aircraft from operatingwithin a defined area on a temporary basis to protectpersons or property in the air or on the ground. Whilenot all inclusive, TFRs may be issued for disaster orhazard situations such as: toxic gas leaks or spills,fumes from flammable agents, aircraft accident/in-cident sites, aviation or ground resources engaged inwildfire suppression, or aircraft relief activitiesfollowing a disaster. TFRs may also be issued insupport of VIP movements, for reasons of nationalsecurity; or when determined necessary for themanagement of air traffic in the vicinity of aerialdemonstrations or major sporting events. NAS usersor other interested parties should contact a FSS forTFR information. Additionally, TFR information canbe found in automated briefings, NOTAM publica-tions, and on the internet at http://www.faa.gov. TheFAA also distributes TFR information to aviationuser groups for further dissemination.

TENTATIVE CALCULATED LANDING TIME(TCLT)− A projected time calculated for adaptedvertex for each arrival aircraft based upon runwayconfiguration, airport acceptance rate, airport arrivaldelay period, and other metered arrival aircraft. Thistime is either the VTA of the aircraft or theTCLT/ACLT of the previous aircraft plus the AAI,whichever is later. This time will be updated inresponse to an aircraft’s progress and its currentrelationship to other arrivals.

TERMINAL AREA− A general term used to describeairspace in which approach control service or airporttraffic control service is provided.

TERMINAL AREA FACILITY− A facility provid-ing air traffic control service for arriving anddeparting IFR, VFR, Special VFR, and on occasionen route aircraft.

(See APPROACH CONTROL FACILITY.)(See TOWER.)

TERMINAL AUTOMATION SYSTEMS (TAS)−TAS is used to identify the numerous automatedtracking systems including ARTS IIE, ARTS IIIA,ARTS IIIE, STARS, and MEARTS.

TERMINAL DATA LINK SYSTEM (TDLS)− Asystem that provides Digital Automatic Terminal


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Information Service (D−ATIS) both on a specifiedradio frequency and also, for subscribers, in a textmessage via data link to the cockpit or to a gateprinter. TDLS also provides Pre−departure Clear-ances (PDC), at selected airports, to subscribers,through a service provider, in text to the cockpit or toa gate printer. In addition, TDLS will emulate theFlight Data Input/Output (FDIO) information withinthe control tower.

TERMINAL RADAR SERVICE AREA− Airspacesurrounding designated airports wherein ATCprovides radar vectoring, sequencing, and separationon a full-time basis for all IFR and participating VFRaircraft. The AIM contains an explanation of TRSA.TRSAs are depicted on VFR aeronautical charts.Pilot participation is urged but is not mandatory.

TERMINAL VFR RADAR SERVICE− A nationalprogram instituted to extend the terminal radarservices provided instrument flight rules (IFR)aircraft to visual flight rules (VFR) aircraft. Theprogram is divided into four types service referred toas basic radar service, terminal radar service area(TRSA) service, Class B service and Class C service.The type of service provided at a particular locationis contained in the Chart Supplement U.S.

a. Basic Radar Service− These services areprovided for VFR aircraft by all commissionedterminal radar facilities. Basic radar service includessafety alerts, traffic advisories, limited radarvectoring when requested by the pilot, andsequencing at locations where procedures have beenestablished for this purpose and/or when covered bya letter of agreement. The purpose of this service is toadjust the flow of arriving IFR and VFR aircraft intothe traffic pattern in a safe and orderly manner and toprovide traffic advisories to departing VFR aircraft.

b. TRSA Service− This service provides, inaddition to basic radar service, sequencing of all IFRand participating VFR aircraft to the primary airportand separation between all participating VFRaircraft. The purpose of this service is to provideseparation between all participating VFR aircraft andall IFR aircraft operating within the area defined as aTRSA.

c. Class C Service− This service provides, inaddition to basic radar service, approved separationbetween IFR and VFR aircraft, and sequencing of

VFR aircraft, and sequencing of VFR arrivals to theprimary airport.

d. Class B Service− This service provides, inaddition to basic radar service, approved separationof aircraft based on IFR, VFR, and/or weight, andsequencing of VFR arrivals to the primary airport(s).

(See CONTROLLED AIRSPACE.)(See TERMINAL RADAR SERVICE AREA.)(Refer to AIM.)(Refer to CHART SUPPLEMENT U.S.)

TERMINAL-VERY HIGH FREQUENCY OMNI-DIRECTIONAL RANGE STATION (TVOR)− Avery high frequency terminal omnirange stationlocated on or near an airport and used as an approachaid.

(See NAVIGATIONAL AID.)(See VOR.)

TERRAIN AWARENESS WARNING SYSTEM(TAWS)− An on−board, terrain proximity alertingsystem providing the aircrew ‘Low Altitudewarnings’ to allow immediate pilot action.

TERRAIN FOLLOWING− The flight of a militaryaircraft maintaining a constant AGL altitude abovethe terrain or the highest obstruction. The altitude ofthe aircraft will constantly change with the varyingterrain and/or obstruction.

TETRAHEDRON− A device normally located onuncontrolled airports and used as a landing directionindicator. The small end of a tetrahedron points in thedirection of landing. At controlled airports, thetetrahedron, if installed, should be disregardedbecause tower instructions supersede the indicator.

(See SEGMENTED CIRCLE.)(Refer to AIM.)

TF−(See TERRAIN FOLLOWING.)

THAT IS CORRECT− The understanding you haveis right.

THA−(See TRANSITIONAL HAZARD AREA.)

THREE−HOUR TARMAC RULE– Rule that relatesto Department of Transportation (DOT) requirementsplaced on airlines when tarmac delays are anticipatedto reach 3 hours.

360 OVERHEAD−(See OVERHEAD MANEUVER.)



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THRESHOLD− The beginning of that portion of therunway usable for landing.

(See AIRPORT LIGHTING.)(See DISPLACED THRESHOLD.)

THRESHOLD CROSSING HEIGHT− Thetheoretical height above the runway threshold atwhich the aircraft’s glideslope antenna would be ifthe aircraft maintains the trajectory established by themean ILS glideslope or the altitude at which thecalculated glidepath of an RNAV or GPS approaches.

(See GLIDESLOPE.)(See THRESHOLD.)

THRESHOLD LIGHTS−(See AIRPORT LIGHTING.)

TIBS−(See TELEPHONE INFORMATION BRIEFINGSERVICE.)

TIE-IN FACILITY– The FSS primarily responsiblefor providing FSS services, including telecommu-nications serv ices for landing facil i t ies ornavigational aids located within the boundaries of aflight plan area (FPA). Three-letter identifiers areassigned to each FSS/FPA and are annotated as tie-infacilities in the Chart Supplement U.S., the AlaskaSupplement, the Pacific Supplement, and FAA OrderJO 7350.9, Location Identifiers. Large consolidatedFSS facilities may have many tie-in facilities or FSSsectors within one facility.

(See FLIGHT PLAN AREA.)(See FLIGHT SERVICE STATION.)

TIME BASED FLOW MANAGEMENT (TBFM)−The hardware, software, methods, processes, andinitiatives to manage air traffic flows based on timeto balance air traffic demand with system capacity,and support the management of PBN. This includes,but not limited to, Adjacent Center Metering (ACM),En Route Departure Capability (EDC),Ground−based Interval Management-Spacing(GIM-S), Integrated Departure/Arrival Capability(IDAC), Single Center Metering (SCM),Time-Based Metering (TBM), Time-BasedScheduling (TBS), and Extended/Coupled Metering.

TIME GROUP− Four digits representing the hourand minutes from the Coordinated Universal Time(UTC) clock. FAA uses UTC for all operations. Theterm “ZULU” may be used to denote UTC. The word“local” or the time zone equivalent shall be used todenote local when local time is given during radio and

telephone communications. When written, a timezone designator is used to indicate local time; e.g.,“0205M” (Mountain). The local time may be basedon the 24-hour clock system. The day begins at 0000and ends at 2359.

TIS−B−(See TRAFFIC INFORMATIONSERVICE−BROADCAST.)

TMPA−(See TRAFFIC MANAGEMENT PROGRAMALERT.)

TMU−(See TRAFFIC MANAGEMENT UNIT.)

TODA−(See TAKEOFF DISTANCE AVAILABLE.)(See ICAO term TAKEOFF DISTANCEAVAILABLE.)

TOI−(See TRACK OF INTEREST.)

TOP ALTITUDE− In reference to SID publishedaltitude restrictions, the charted “maintain” altitudecontained in the procedure description or assigned byATC.

TORA−(See TAKEOFF RUN AVAILABLE.)(See ICAO term TAKEOFF RUN AVAILABLE.)

TORCHING− The burning of fuel at the end of anexhaust pipe or stack of a reciprocating aircraftengine, the result of an excessive richness in the fuelair mixture.

TOS−(See TRAJECTORY OPTIONS SET)

TOTAL ESTIMATED ELAPSED TIME [ICAO]−For IFR flights, the estimated time required fromtakeoff to arrive over that designated point, definedby reference to navigation aids, from which it isintended that an instrument approach procedure willbe commenced, or, if no navigation aid is associatedwith the destination aerodrome, to arrive over thedestination aerodrome. For VFR flights, theestimated time required from takeoff to arrive overthe destination aerodrome.

(See ICAO term ESTIMATED ELAPSED TIME.)

TOUCH-AND-GO− An operation by an aircraft thatlands and departs on a runway without stopping orexiting the runway.



PCG T−5

TOUCH-AND-GO LANDING−

(See TOUCH-AND-GO.)

TOUCHDOWN−

a. The point at which an aircraft first makescontact with the landing surface.

b. Concerning a precision radar approach (PAR),it is the point where the glide path intercepts thelanding surface.

(See ICAO term TOUCHDOWN.)

TOUCHDOWN [ICAO]− The point where thenominal glide path intercepts the runway.

Note: Touchdown as defined above is only a datumand is not necessarily the actual point at which theaircraft will touch the runway.

TOUCHDOWN RVR−

(See VISIBILITY.)

TOUCHDOWN ZONE− The first 3,000 feet of therunway beginning at the threshold. The area is usedfor determination of Touchdown Zone Elevation inthe development of straight-in landing minimums forinstrument approaches.

(See ICAO term TOUCHDOWN ZONE.)

TOUCHDOWN ZONE [ICAO]− The portion of arunway, beyond the threshold, where it is intendedlanding aircraft first contact the runway.

TOUCHDOWN ZONE ELEVATION− The highestelevation in the first 3,000 feet of the landing surface.TDZE is indicated on the instrument approachprocedure chart when straight-in landing minimumsare authorized.

(See TOUCHDOWN ZONE.)

TOUCHDOWN ZONE LIGHTING−

(See AIRPORT LIGHTING.)

TOWER− A terminal facility that uses air/groundcommunications, visual signaling, and other devicesto provide ATC services to aircraft operating in thevicinity of an airport or on the movement area.Authorizes aircraft to land or takeoff at the airportcontrolled by the tower or to transit the Class Dairspace area regardless of flight plan or weather

conditions (IFR or VFR). A tower may also provideapproach control services (radar or nonradar).

(See AIRPORT TRAFFIC CONTROL SERVICE.)(See APPROACH CONTROL FACILITY.)(See APPROACH CONTROL SERVICE.)(See MOVEMENT AREA.)(See TOWER EN ROUTE CONTROLSERVICE.)

(See ICAO term AERODROME CONTROLTOWER.)

(Refer to AIM.)

TOWER EN ROUTE CONTROL SERVICE− Thecontrol of IFR en route traffic within delegatedairspace between two or more adjacent approachcontrol facilities. This service is designed to expeditetraffic and reduce control and pilot communicationrequirements.

TOWER TO TOWER−(See TOWER EN ROUTE CONTROLSERVICE.)

TRACEABLE PRESSURE STANDARD− Thefacility station pressure instrument, with certifica-tion/calibration traceable to the National Institute ofStandards and Technology. Traceable pressurestandards may be mercurial barometers, commis-sioned ASOS or dual transducer AWOS, or portablepressure standards or DASI.

TRACK− The actual flight path of an aircraft over thesurface of the earth.

(See COURSE.)(See FLIGHT PATH.)(See ROUTE.)(See ICAO term TRACK.)

TRACK [ICAO]− The projection on the earth’ssurface of the path of an aircraft, the direction ofwhich path at any point is usually expressed indegrees from North (True, Magnetic, or Grid).

TRACK OF INTEREST (TOI)− Displayed datarepresenting an airborne object that threatens or hasthe potential to threaten North America or NationalSecurity. Indicators may include, but are not limitedto: noncompliance with air traffic control instructionsor aviation regulations; extended loss of communica-tions; unusual transmissions or unusual flightbehavior; unauthorized intrusion into controlledairspace or an ADIZ; noncompliance with issuedflight restrictions/security procedures; or unlawfulinterference with airborne flight crews, up to andincluding hijack. In certain circumstances, an object



PCG T−6

may become a TOI based on specific and credibleintelligence pertaining to that particular aircraft/object, its passengers, or its cargo.

TRACK OF INTEREST RESOLUTION− A TOIwill normally be considered resolved when: theaircraft/object is no longer airborne; the aircraftcomplies with air traffic control instructions, aviationregulations, and/or issued flight restrictions/securityprocedures; radio contact is re−established andauthorized control of the aircraft is verified; theaircraft is intercepted and intent is verified to benonthreatening/nonhostile; TOI was identified basedon specific and credible intelligence that was laterdetermined to be invalid or unreliable; or displayeddata is identified and characterized as invalid.

TRAFFIC−

a. A term used by a controller to transfer radaridentification of an aircraft to another controller forthe purpose of coordinating separation action. Trafficis normally issued:

1. In response to a handoff or point out,

2. In anticipation of a handoff or point out, or

3. In conjunction with a request for control of anaircraft.

b. A term used by ATC to refer to one or moreaircraft.

TRAFFIC ADVISORIES− Advisories issued to alertpilots to other known or observed air traffic whichmay be in such proximity to the position or intendedroute of flight of their aircraft to warrant theirattention. Such advisories may be based on:

a. Visual observation.

b. Observation of radar identified and nonidenti-fied aircraft targets on an ATC radar display, or

c. Verbal reports from pilots or other facilities.Note 1: The word “traffic” followed by additionalinformation, if known, is used to provide suchadvisories; e.g., “Traffic, 2 o’clock, one zero miles,southbound, eight thousand.”

Note 2: Traffic advisory service will be provided tothe extent possible depending on higher priorityduties of the controller or other limitations; e.g.,radar limitations, volume of traffic, frequencycongestion, or controller workload. Radar/nonradar traffic advisories do not relieve the pilotof his/her responsibility to see and avoid otheraircraft. Pilots are cautioned that there are manytimes when the controller is not able to give traffic

advisories concerning all traffic in the aircraft’sproximity; in other words, when a pilot requests oris receiving traffic advisories, he/she should notassume that all traffic will be issued.

(Refer to AIM.)

TRAFFIC ALERT (aircraft call sign), TURN(left/right) IMMEDIATELY, (climb/descend) ANDMAINTAIN (altitude).

(See SAFETY ALERT.)

TRAFFIC ALERT AND COLLISION AVOID-ANCE SYSTEM (TCAS)− An airborne collisionavoidance system based on radar beacon signalswhich operates independent of ground-based equip-ment. TCAS-I generates traffic advisories only.TCAS-II generates traffic advisories, and resolution(collision avoidance) advisories in the vertical plane.

TRAFFIC INFORMATION−(See TRAFFIC ADVISORIES.)

TRAFFIC INFORMATION SERVICE−BROAD-CAST (TIS−B)− The broadcast of ATC derivedtraffic information to ADS−B equipped (1090ES orUAT) aircraft. The source of this traffic informationis derived from ground−based air traffic surveillancesensors, typically from radar targets. TIS−B servicewill be available throughout the NAS where there areboth adequate surveillance coverage (radar) andadequate broadcast coverage from ADS−B groundstations. Loss of TIS−B will occur when an aircraftenters an area not covered by the GBT network. If thisoccurs in an area with adequate surveillance coverage(radar), nearby aircraft that remain within theadequate broadcast coverage (ADS−B) area will viewthe first aircraft. TIS−B may continue when anaircraft enters an area with inadequate surveillancecoverage (radar); nearby aircraft that remain withinthe adequate broadcast coverage (ADS−B) area willnot view the first aircraft.

TRAFFIC IN SIGHT− Used by pilots to inform acontroller that previously issued traffic is in sight.

(See NEGATIVE CONTACT.)(See TRAFFIC ADVISORIES.)

TRAFFIC MANAGEMENT PROGRAM ALERT−A term used in a Notice to Airmen (NOTAM) issuedin conjunction with a special traffic managementprogram to alert pilots to the existence of the programand to refer them to either the Notices to Airmenpublication or a special traffic management programadvisory message for program details. The contrac-tion TMPA is used in NOTAM text.



PCG T−7

TRAFFIC MANAGEMENT UNIT− The entity inARTCCs and designated terminals directly involvedin the active management of facility traffic. Usuallyunder the direct supervision of an assistant managerfor traffic management.

TRAFFIC NO FACTOR− Indicates that the trafficdescribed in a previously issued traffic advisory is nofactor.

TRAFFIC NO LONGER OBSERVED− Indicatesthat the traffic described in a previously issued trafficadvisory is no longer depicted on radar, but may stillbe a factor.

TRAFFIC PATTERN− The traffic flow that isprescribed for aircraft landing at, taxiing on, or takingoff from an airport. The components of a typicaltraffic pattern are upwind leg, crosswind leg,downwind leg, base leg, and final approach.

a. Upwind Leg− A flight path parallel to thelanding runway in the direction of landing.

b. Crosswind Leg− A flight path at right angles tothe landing runway off its upwind end.

c. Downwind Leg− A flight path parallel to thelanding runway in the direction opposite to landing.The downwind leg normally extends between thecrosswind leg and the base leg.

d. Base Leg− A flight path at right angles to thelanding runway off its approach end. The base legnormally extends from the downwind leg to theintersection of the extended runway centerline.

e. Final Approach− A flight path in the directionof landing along the extended runway centerline. Thefinal approach normally extends from the base leg tothe runway. An aircraft making a straight-in approachVFR is also considered to be on final approach.

(See STRAIGHT-IN APPROACH VFR.)(See TAXI PATTERNS.)(See ICAO term AERODROME TRAFFICCIRCUIT.)


TRAFFIC SITUATION DISPLAY (TSD)− TSD is acomputer system that receives radar track data fromall 20 CONUS ARTCCs, organizes this data into amosaic display, and presents it on a computer screen.The display allows the traffic management coordina-tor multiple methods of selection and highlighting ofindividual aircraft or groups of aircraft. The user hasthe option of superimposing these aircraft positions

over any number of background displays. Thesebackground options include ARTCC boundaries, anystratum of en route sector boundaries, fixes, airways,military and other special use airspace, airports, andgeopolitical boundaries. By using the TSD, acoordinator can monitor any number of trafficsituations or the entire systemwide traffic flows.

TRAJECTORY− A EDST representation of the pathan aircraft is predicted to fly based upon a CurrentPlan or Trial Plan.


TRAJECTORY MODELING− The automated pro-cess of calculating a trajectory.

TRAJECTORY OPTIONS SET (TOS)− A TOS is anelectronic message, submitted by the operator, that isused by the Collaborative Trajectory OptionsProgram (CTOP) to manage the airspace captured inthe traffic management program. The TOS will allowthe operator to express the route and delay trade-offoptions that they are willing to accept.

TRANSCRIBED WEATHER BROADCAST(TWEB)− A continuous recording of meteorologicaland aeronautical information that is broadcast onL/MF and VOR facilities for pilots. (Provided onlyin Alaska.)

(Refer to AIM.)

TRANSFER OF CONTROL− That action wherebythe responsibility for the separation of an aircraft istransferred from one controller to another.

(See ICAO term TRANSFER OF CONTROL.)

TRANSFER OF CONTROL [ICAO]− Transfer ofresponsibility for providing air traffic control service.

TRANSFERRING CONTROLLER− A controller/facility transferring control of an aircraft to anothercontroller/facility.

(See ICAO term TRANSFERRINGUNIT/CONTROLLER.)

TRANSFERRING FACILITY−(See TRANSFERRING CONTROLLER.)

TRANSFERRING UNIT/CONTROLLER [ICAO]−Air traffic control unit/air traffic controller in theprocess of transferring the responsibility forproviding air traffic control service to an aircraft tothe next air traffic control unit/air traffic controlleralong the route of flight.

Note: See definition of accepting unit/controller.



PCG T−8

TRANSITION−

a. The general term that describes the change fromone phase of flight or flight condition to another; e.g.,transition from en route flight to the approach ortransition from instrument flight to visual flight.

b. A published procedure (DP Transition) used toconnect the basic DP to one of several en routeairways/jet routes, or a published procedure (STARTransition) used to connect one of several en routeairways/jet routes to the basic STAR.

(Refer to DP/STAR Charts.)

TRANSITION POINT− A point at an adaptednumber of miles from the vertex at which an arrivalaircraft would normally commence descent from itsen route altitude. This is the first fix adapted on thearrival speed segments.

TRANSITION WAYPOINT− The waypoint thatdefines the beginning of a runway or en routetransition on an RNAV SID or STAR.

TRANSITIONAL AIRSPACE− That portion ofcontrolled airspace wherein aircraft change from onephase of flight or flight condition to another.

TRANSITIONAL HAZARD AREA (THA)− Usedby ATC. Airspace normally associated with anAircraft Hazard Area within which the flight ofaircraft is subject to restrictions.

(See AIRCRAFT HAZARD AREA.)(See CONTINGENCY HAZARD AREA.)(See REFINED HAZARD AREA.)

TRANSMISSOMETER− An apparatus used todetermine visibility by measuring the transmission oflight through the atmosphere. It is the measurementsource for determining runway visual range (RVR).

(See VISIBILITY.)

TRANSMITTING IN THE BLIND− A transmis-sion from one station to other stations incircumstances where two-way communicationcannot be established, but where it is believed that thecalled stations may be able to receive thetransmission.

TRANSPONDER− The airborne radar beaconreceiver/transmitter portion of the Air Traffic ControlRadar Beacon System (ATCRBS) which automati-cally receives radio signals from interrogators on theground, and selectively replies with a specific replypulse or pulse group only to those interrogations

being received on the mode to which it is set torespond.

(See INTERROGATOR.)(See ICAO term TRANSPONDER.)(Refer to AIM.)

TRANSPONDER [ICAO]− A receiver/transmitterwhich will generate a reply signal upon properinterrogation; the interrogation and reply being ondifferent frequencies.

TRANSPONDER CODES−(See CODES.)

TRANSPONDER OBSERVED − Phraseology usedto inform a VFR pilot the aircraft’s assigned beaconcode and position have been observed. Specifically,this term conveys to a VFR pilot the transponderreply has been observed and its position correlated fortransit through the designated area.

TRIAL PLAN− A proposed amendment whichutilizes automation to analyze and display potentialconflicts along the predicted trajectory of the selectedaircraft.

TRSA−(See TERMINAL RADAR SERVICE AREA.)

TSD−(See TRAFFIC SITUATION DISPLAY.)

TURBOJET AIRCRAFT− An aircraft having a jetengine in which the energy of the jet operates aturbine which in turn operates the air compressor.

TURBOPROP AIRCRAFT− An aircraft having a jetengine in which the energy of the jet operates aturbine which drives the propeller.

TURBULENCE− An atmospheric phenomenon thatcauses changes in aircraft altitude, attitude, and orairspeed with aircraft reaction depending onintensity. Pilots report turbulence intensity accordingto aircraft’s reaction as follows:

a. Light − Causes slight, erratic changes in altitudeand or attitude (pitch, roll, or yaw).

b. Moderate− Similar to Light but of greaterintensity. Changes in altitude and or attitude occurbut the aircraft remains in positive control at all times.It usually causes variations in indicated airspeed.

c. Severe− Causes large, abrupt changes in altitudeand or attitude. It usually causes large variations inindicated airspeed. Aircraft may be momentarily outof control.



PCG T−9

d. Extreme− The aircraft is violently tossed aboutand is practically impossible to control. It may causestructural damage.

(See CHOP.)(Refer to AIM.)

TURN ANTICIPATION− (maneuver anticipation).

TVOR−(See TERMINAL-VERY HIGH FREQUENCYOMNIDIRECTIONAL RANGE STATION.)

TWEB−(See TRANSCRIBED WEATHER BROADCAST.)

TWO-WAY RADIO COMMUNICATIONS FAIL-URE−




PCG U−1

UUHF−

(See ULTRAHIGH FREQUENCY.)

ULTRAHIGH FREQUENCY (UHF)− The frequen-cy band between 300 and 3,000 MHz. The bank ofradio frequencies used for military air/ground voicecommunications. In some instances this may go aslow as 225 MHz and still be referred to as UHF.

ULTRALIGHT VEHICLE− A single-occupantaeronautical vehicle operated for sport or recreationalpurposes which does not require FAA registration, anairworthiness certificate, or pilot certification.Operation of an ultralight vehicle in certain airspacerequires authorization from ATC.


UNABLE− Indicates inability to comply with aspecific instruction, request, or clearance.

UNASSOCIATED− A radar target that does notdisplay a data block with flight identification andaltitude information.

(See ASSOCIATED.)

UNCONTROLLED AIRSPACE− Airspace in whichaircraft are not subject to controlled airspace (ClassA, B, C, D, or E) separation criteria.

UNDER THE HOOD− Indicates that the pilot isusing a hood to restrict visibility outside the cockpitwhile simulating instrument flight. An appropriatelyrated pilot is required in the other control seat whilethis operation is being conducted.


UNFROZEN− The Scheduled Time of Arrival (STA)tags, which are still being rescheduled by the timebased flow management (TBFM) calculations. Theaircraft will remain unfrozen until the time thecorresponding estimated time of arrival (ETA) tagpasses the preset freeze horizon for that aircraft’sstream class. At this point the automatic reschedulingwill stop, and the STA becomes “frozen.”

UNICOM− A nongovernment communication facil-ity which may provide airport information at certainairports. Locations and frequencies of UNICOMs areshown on aeronautical charts and publications.

(See CHART SUPPLEMENT U.S.)(Refer to AIM.)

UNMANNED AIRCRAFT (UA)- A device used orintended to be used for flight that has no onboardpilot. This device can be any type of airplane,helicopter, airship, or powered-lift aircraft.Unmanned free balloons, moored balloons, tetheredaircraft, gliders, and unmanned rockets are notconsidered to be a UA.

UNMANNED AIRCRAFT SYSTEM (UAS)- Anunmanned aircraft and its associated elements relatedto safe operations, which may include controlstations (ground, ship, or air based), control links,support equipment, payloads, flight terminationsystems, and launch/recovery equipment. It consistsof three elements: unmanned aircraft, control station,and data link.

UNPUBLISHED ROUTE− A route for which nominimum altitude is published or charted for pilotuse. It may include a direct route between NAVAIDs,a radial, a radar vector, or a final approach coursebeyond the segments of an instrument approachprocedure.

(See PUBLISHED ROUTE.)(See ROUTE.)

UNRELIABLE (GPS/WAAS)− An advisory topilots indicating the expected level of service of theGPS and/or WAAS may not be available. Pilots mustthen determine the adequacy of the signal for desireduse.

UNSERVICEABLE (U/S)(See OUT OF SERVICE/UNSERVICEABLE.)

UPWIND LEG−(See TRAFFIC PATTERN.)

URGENCY− A condition of being concerned aboutsafety and of requiring timely but not immediateassistance; a potential distress condition.

(See ICAO term URGENCY.)

URGENCY [ICAO]− A condition concerning thesafety of an aircraft or other vehicle, or of person onboard or in sight, but which does not requireimmediate assistance.

USAFIB−(See ARMY AVIATION FLIGHT INFORMATIONBULLETIN.)



PCG V−1

VVASI−

(See VISUAL APPROACH SLOPE INDICATOR.)

VCOA−(See VISUAL CLIMB OVER AIRPORT.)

VDP−(See VISUAL DESCENT POINT.)

VECTOR− A heading issued to an aircraft to providenavigational guidance by radar.

(See ICAO term RADAR VECTORING.)

VERIFY− Request confirmation of information;e.g., “verify assigned altitude.”

VERIFY SPECIFIC DIRECTION OF TAKEOFF(OR TURNS AFTER TAKEOFF)− Used by ATC toascertain an aircraft’s direction of takeoff and/ordirection of turn after takeoff. It is normally used forIFR departures from an airport not having a controltower. When direct communication with the pilot isnot possible, the request and information may berelayed through an FSS, dispatcher, or by othermeans.


VERTEX− The last fix adapted on the arrival speedsegments. Normally, it will be the outer marker of therunway in use. However, it may be the actualthreshold or other suitable common point on theapproach path for the particular runway configura-tion.

VERTEX TIME OF ARRIVAL− A calculated time ofaircraft arrival over the adapted vertex for the runwayconfiguration in use. The time is calculated via theoptimum flight path using adapted speed segments.

VERTICAL NAVIGATION (VNAV)– A function ofarea navigation (RNAV) equipment which calculates,displays, and provides vertical guidance to a profileor path.

VERTICAL SEPARATION− Separation betweenaircraft expressed in units of vertical distance.

(See SEPARATION.)

VERTICAL TAKEOFF AND LANDING AIR-CRAFT (VTOL)− Aircraft capable of vertical climbs

and/or descents and of using very short runways orsmall areas for takeoff and landings. These aircraftinclude, but are not limited to, helicopters.

(See SHORT TAKEOFF AND LANDINGAIRCRAFT.)

VERY HIGH FREQUENCY (VHF)− The frequencyband between 30 and 300 MHz. Portions of this band,108 to 118 MHz, are used for certain NAVAIDs; 118to 136 MHz are used for civil air/ground voicecommunications. Other frequencies in this band areused for purposes not related to air traffic control.

VERY HIGH FREQUENCY OMNIDIRECTION-AL RANGE STATION−

(See VOR.)

VERY LOW FREQUENCY (VLF)− The frequencyband between 3 and 30 kHz.

VFR−(See VISUAL FLIGHT RULES.)

VFR AIRCRAFT− An aircraft conducting flight inaccordance with visual flight rules.

(See VISUAL FLIGHT RULES.)

VFR CONDITIONS− Weather conditions equal toor better than the minimum for flight under visualflight rules. The term may be used as an ATCclearance/instruction only when:

a. An IFR aircraft requests a climb/descent inVFR conditions.

b. The clearance will result in noise abatementbenefits where part of the IFR departure route doesnot conform to an FAA approved noise abatementroute or altitude.

c. A pilot has requested a practice instrumentapproach and is not on an IFR flight plan.

Note: All pilots receiving this authorization mustcomply with the VFR visibility and distance fromcloud criteria in 14 CFR Part 91. Use of the termdoes not relieve controllers of their responsibility toseparate aircraft in Class B and Class C airspaceor TRSAs as required by FAA Order JO 7110.65.When used as an ATC clearance/instruction, theterm may be abbreviated “VFR;” e.g., “MAINTAINVFR,” “CLIMB/DESCEND VFR,” etc.

VFR FLIGHT−(See VFR AIRCRAFT.)


PCG V−2

VFR MILITARY TRAINING ROUTES (VR)−Routes used by the Department of Defense andassociated Reserve and Air Guard units for thepurpose of conducting low-altitude navigation andtactical training under VFR below 10,000 feet MSLat airspeeds in excess of 250 knots IAS.

VFR NOT RECOMMENDED− An advisoryprovided by a flight service station to a pilot duringa preflight or inflight weather briefing that flightunder visual flight rules is not recommended. To begiven when the current and/or forecast weatherconditions are at or below VFR minimums. It doesnot abrogate the pilot’s authority to make his/her owndecision.

VFR-ON-TOP− ATC authorization for an IFRaircraft to operate in VFR conditions at anyappropriate VFR altitude (as specified in 14 CFR andas restricted by ATC). A pilot receiving thisauthorization must comply with the VFR visibility,distance from cloud criteria, and the minimum IFRaltitudes specified in 14 CFR Part 91. The use of thisterm does not relieve controllers of their responsibil-ity to separate aircraft in Class B and Class C airspaceor TRSAs as required by FAA Order JO 7110.65.

VFR TERMINAL AREA CHARTS−(See AERONAUTICAL CHART.)

VFR WAYPOINT−(See WAYPOINT.)

VHF−(See VERY HIGH FREQUENCY.)

VHF OMNIDIRECTIONAL RANGE/TACTICALAIR NAVIGATION−

(See VORTAC.)

VIDEO MAP− An electronically displayed map onthe radar display that may depict data such as airports,heliports, runway centerline extensions, hospitalemergency landing areas, NAVAIDs and fixes,reporting points, airway/route centerlines, bound-aries, handoff points, special use tracks, obstructions,prominent geographic features, map alignmentindicators, range accuracy marks, and/or minimumvectoring altitudes.

VISIBILITY− The ability, as determined byatmospheric conditions and expressed in units ofdistance, to see and identify prominent unlightedobjects by day and prominent lighted objects by

night. Visibility is reported as statute miles, hundredsof feet or meters.

(Refer to 14 CFR Part 91.)(Refer to AIM.)a. Flight Visibility− The average forward horizon-

tal distance, from the cockpit of an aircraft in flight,at which prominent unlighted objects may be seenand identified by day and prominent lighted objectsmay be seen and identified by night.

b. Ground Visibility− Prevailing horizontal visi-bility near the earth’s surface as reported by theUnited States National Weather Service or anaccredited observer.

c. Prevailing Visibility− The greatest horizontalvisibility equaled or exceeded throughout at least halfthe horizon circle which need not necessarily becontinuous.

d. Runway Visual Range (RVR)− An instrumen-tally derived value, based on standard calibrations,that represents the horizontal distance a pilot will seedown the runway from the approach end. It is basedon the sighting of either high intensity runway lightsor on the visual contrast of other targets whicheveryields the greater visual range. RVR, in contrast toprevailing or runway visibility, is based on what apilot in a moving aircraft should see looking down therunway. RVR is horizontal visual range, not slantvisual range. It is based on the measurement of atransmissometer made near the touchdown point ofthe instrument runway and is reported in hundreds offeet. RVR, where available, is used in lieu ofprevailing visibility in determining minimums for aparticular runway.

1. Touchdown RVR− The RVR visibilityreadout values obtained from RVR equipmentserving the runway touchdown zone.

2. Mid-RVR− The RVR readout values obtainedfrom RVR equipment located midfield of the runway.

3. Rollout RVR− The RVR readout valuesobtained from RVR equipment located nearest therollout end of the runway.

(See ICAO term FLIGHT VISIBILITY.)(See ICAO term GROUND VISIBILITY.)(See ICAO term RUNWAY VISUAL RANGE.)(See ICAO term VISIBILITY.)

VISIBILITY [ICAO]− The ability, as determined byatmospheric conditions and expressed in units ofdistance, to see and identify prominent unlightedobjects by day and prominent lighted objects bynight.



PCG V−3

a. Flight Visibility− The visibility forward fromthe cockpit of an aircraft in flight.

b. Ground Visibility− The visibility at anaerodrome as reported by an accredited observer.

c. Runway Visual Range [RVR]− The range overwhich the pilot of an aircraft on the centerline of arunway can see the runway surface markings or thelights delineating the runway or identifying itscenterline.

VISUAL APPROACH− An approach conducted onan instrument flight rules (IFR) flight plan whichauthorizes the pilot to proceed visually and clear ofclouds to the airport. The pilot must, at all times, haveeither the airport or the preceding aircraft in sight.This approach must be authorized and under thecontrol of the appropriate air traffic control facility.Reported weather at the airport must be: ceiling at orabove 1,000 feet, and visibility of 3 miles or greater.

(See ICAO term VISUAL APPROACH.)

VISUAL APPROACH [ICAO]− An approach by anIFR flight when either part or all of an instrumentapproach procedure is not completed and theapproach is executed in visual reference to terrain.

VISUAL APPROACH SLOPE INDICATOR(VASI)−

(See AIRPORT LIGHTING.)

VISUAL CLIMB OVER AIRPORT (VCOA)− Adeparture option for an IFR aircraft, operating invisual meteorological conditions equal to or greaterthan the specified visibility and ceiling, to visuallyconduct climbing turns over the airport to thepublished “climb−to” altitude from which to proceedwith the instrument portion of the departure. VCOAprocedures are developed to avoid obstacles greaterthan 3 statute miles from the departure end of therunway as an alternative to complying with climbgradients greater than 200 feet per nautical mile.Pilots are responsible to advise ATC as early aspossible of the intent to fly the VCOA option prior todeparture. These textual procedures are published inthe ‘Take−Off Minimums and (Obstacle) DepartureProcedures’ section of the Terminal ProceduresPublications and/or appear as an option on a GraphicODP.

(See AIM.)

VISUAL DESCENT POINT− A defined point on thefinal approach course of a nonprecision straight-inapproach procedure from which normal descent fromthe MDA to the runway touchdown point may becommenced, provided the approach threshold of thatrunway, or approach lights, or other markingsidentifiable with the approach end of that runway areclearly visible to the pilot.

VISUAL FLIGHT RULES− Rules that govern theprocedures for conducting flight under visualconditions. The term “VFR” is also used in theUnited States to indicate weather conditions that areequal to or greater than minimum VFR requirements.In addition, it is used by pilots and controllers toindicate type of flight plan.

(See INSTRUMENT FLIGHT RULES.)(See INSTRUMENT METEOROLOGICALCONDITIONS.)

(See VISUAL METEOROLOGICALCONDITIONS.)


VISUAL HOLDING− The holding of aircraft atselected, prominent geographical fixes which can beeasily recognized from the air.

(See HOLDING FIX.)

VISUAL METEOROLOGICAL CONDITIONS−Meteorological conditions expressed in terms ofvisibility, distance from cloud, and ceiling equal to orbetter than specified minima.

(See INSTRUMENT FLIGHT RULES.)(See INSTRUMENT METEOROLOGICALCONDITIONS.)

(See VISUAL FLIGHT RULES.)

VISUAL SEGMENT−(See PUBLISHED INSTRUMENT APPROACHPROCEDURE VISUAL SEGMENT.)

VISUAL SEPARATION− A means employed byATC to separate aircraft in terminal areas and en routeairspace in the NAS. There are two ways to effect thisseparation:

a. The tower controller sees the aircraft involvedand issues instructions, as necessary, to ensure thatthe aircraft avoid each other.

b. A pilot sees the other aircraft involved and uponinstructions from the controller provides his/her ownseparation by maneuvering his/her aircraft as



PCG V−4

necessary to avoid it. This may involve followinganother aircraft or keeping it in sight until it is nolonger a factor.

(See SEE AND AVOID.)(Refer to 14 CFR Part 91.)

VLF−(See VERY LOW FREQUENCY.)

VMC−(See VISUAL METEOROLOGICALCONDITIONS.)

VOICE SWITCHING AND CONTROL SYSTEM(VSCS)− A computer controlled switching systemthat provides air traffic controllers with all voicecircuits (air to ground and ground to ground)necessary for air traffic control.

(Refer to AIM.)

VOR− A ground-based electronic navigation aidtransmitting very high frequency navigation signals,360 degrees in azimuth, oriented from magneticnorth. Used as the basis for navigation in the NationalAirspace System. The VOR periodically identifiesitself by Morse Code and may have an additionalvoice identification feature. Voice features may beused by ATC or FSS for transmitting instructions/in-formation to pilots.

(See NAVIGATIONAL AID.)(Refer to AIM.)

VOR TEST SIGNAL−(See VOT.)

VORTAC− A navigation aid providing VORazimuth, TACAN azimuth, and TACAN distancemeasuring equipment (DME) at one site.

(See DISTANCE MEASURING EQUIPMENT.)(See NAVIGATIONAL AID.)(See TACAN.)(See VOR.)(Refer to AIM.)

VORTICES− Circular patterns of air created by themovement of an airfoil through the air whengenerating lift. As an airfoil moves through theatmosphere in sustained flight, an area of area of lowpressure is created above it. The air flowing from thehigh pressure area to the low pressure area around andabout the tips of the airfoil tends to roll up into tworapidly rotating vortices, cylindrical in shape. Thesevortices are the most predominant parts of aircraftwake turbulence and their rotational force isdependent upon the wing loading, gross weight, andspeed of the generating aircraft. The vortices frommedium to super aircraft can be of extremely highvelocity and hazardous to smaller aircraft.

(See AIRCRAFT CLASSES.)

(See WAKE TURBULENCE.)(Refer to AIM.)

VOT− A ground facility which emits a test signal tocheck VOR receiver accuracy. Some VOTs areavailable to the user while airborne, and others arelimited to ground use only.

(See CHART SUPPLEMENT U.S.)


VR−(See VFR MILITARY TRAINING ROUTES.)

VSCS−(See VOICE SWITCHING AND CONTROLSYSTEM.)

VTA−(See VERTEX TIME OF ARRIVAL.)

VTOL AIRCRAFT−(See VERTICAL TAKEOFF AND LANDINGAIRCRAFT.)



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WWA−

(See AIRMET.)(See WEATHER ADVISORY.)

WAAS−(See WIDE-AREA AUGMENTATION SYSTEM.)

WAKE TURBULENCE− A phenomenon that occurswhen an aircraft develops lift and forms a pair ofcounter−rotating vortices.

(See AIRCRAFT CLASSES.)(See VORTICES.)(Refer to AIM.)

WARNING AREA−(See SPECIAL USE AIRSPACE.)

WAYPOINT− A predetermined geographical posi-tion used for route/instrument approach definition,progress reports, published VFR routes, visualreporting points or points for transitioning and/orcircumnavigating controlled and/or special useairspace, that is defined relative to a VORTAC stationor in terms of latitude/longitude coordinates.

WEATHER ADVISORY− In aviation weatherforecast practice, an expression of hazardous weatherconditions not predicted in the Aviation SurfaceForecast, Aviation Cloud Forecast, or area forecast,as they affect the operation of air traffic and asprepared by the NWS.

(See AIRMET.)(See SIGMET.)

WEATHER RECONNAISSANCE AREA (WRA)−A WRA is airspace with defined dimensions andpublished by Notice to Airmen, which is establishedto support weather reconnaissance/research flights.Air traffic control services are not provided withinWRAs. Only participating weather reconnaissance/research aircraft from the 53rd WeatherReconnaissance Squadron and National Oceanic andAtmospheric Administration Aircraft OperationsCenter are permitted to operate within a WRA. AWRA may only be established in airspace within U.S.Flight Information Regions outside of U.S. territorialairspace.

WHEN ABLE−

a. In conjunction with ATC instructions, gives thepilot the latitude to delay compliance until acondition or event has been reconciled. Unlike “pilotdiscretion,” when instructions are prefaced “whenable,” the pilot is expected to seek the firstopportunity to comply.

b. In conjunction with a weather deviationclearance, requires the pilot to determine when he/sheis clear of weather, then execute ATC instructions.

c. Once a maneuver has been initiated, the pilot isexpected to continue until the specifications of theinstructions have been met. “When able,” should notbe used when expeditious compliance is required.

WIDE-AREA AUGMENTATION SYSTEM(WAAS)− The WAAS is a satellite navigation systemconsisting of the equipment and software whichaugments the GPS Standard Positioning Service(SPS). The WAAS provides enhanced integrity,accuracy, availability, and continuity over and aboveGPS SPS. The differential correction functionprovides improved accuracy required for precisionapproach.

WIDE AREA MULTILATERATION (WAM)– Adistributed surveillance technology which mayutilize any combination of signals from Air TrafficControl Radar Beacon System (ATCRBS) (Modes Aand C) and Mode S transponders, and ADS-Btransmissions. Multiple geographically dispersedground sensors measure the time-of-arrival of thetransponder messages. Aircraft position is deter-mined by joint processing of thetime-difference-of-arrival (TDOA) measurementscomputed between a reference and the groundstations’ measured time-of-arrival.

WILCO− I have received your message, understandit, and will comply with it.

WIND GRID DISPLAY− A display that presents thelatest forecasted wind data overlaid on a map of theARTCC area. Wind data is automatically entered andupdated periodically by transmissions from theNational Weather Service. Winds at specificaltitudes, along with temperatures and air pressurecan be viewed.

WIND SHEAR− A change in wind speed and/or winddirection in a short distance resulting in a tearing or


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shearing effect. It can exist in a horizontal or verticaldirection and occasionally in both.

WIND SHEAR ESCAPE− An unplanned abortivemaneuver initiated by the pilot in command (PIC) asa result of onboard cockpit systems. Wind shearescapes are characterized by maximum thrust climbsin the low altitude terminal environment until windshear conditions are no longer detected.

WING TIP VORTICES−(See VORTICES.)

WORDS TWICE−

a. As a request: “Communication is difficult.Please say every phrase twice.”

b. As information: “Since communications aredifficult, every phrase in this message will be spokentwice.”

WS−(See SIGMET.)(See WEATHER ADVISORY.)

WST−(See CONVECTIVE SIGMET.)(See WEATHER ADVISORY.)

1/30/20 Pilot/Controller Glossary PILOT/CONTROLLER GLOSSARY · 2020-01-30 · 1/30/20 Pilot/Controller Glossary PCG−1 PILOT/CONTROLLER GLOSSARY PURPOSE a. This Glossary was compiled

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