AVIATION GLOSSARY
AVIATION GLOSSARY
ABSOLUTE ALTITUDE - The measureable height of an aircraft above
the actual terrain.
ABSOLUTE CEILING - The maximum altitude above sea level at which
an aircraft can maintain level flight under Standard Air
conditions.
ACCELERATED STALL - Any stall made to occur at other than
1g.
ACCESSORY GROUP - Mechanical and electrical units mounted on an
engine necessary for its operation, such as starter, magnetos, fuel
pumps, etc.
ADCOCK RANGE - National radio navigation system replaced after
World War 2 by the omnirange system. It consisted of segmented
quadrants broacasting Morse Code "A" (dot-dash) and "N" (dash-dot)
signals in opposing quadrants so that pilots could orient their
position relative to a "beam" broadcasting a steady tone, and a
Morse Code station identifier. Using a "build-and-fade" technique,
a pilot could (ideally) pinpoint his location by the strength or
weakness of a signal.
ADF - Automatic Direction Finding via automated radio.
ADIABATIC LAPSE RATE - The rate at which ascending air cools and
descending air warms, given no heat is added or taken away. The
rate for dry air is based on 5.4 F per 1000' altitude (1 per 100
meters); saturated rates vary with barometric pressures and
temperatures, and must be adjusted for accuracy.
ADVERSE YAW - Yaw generated when the ailerons are used. The
lifting wing generates more drag, causing an airplane to yaw toward
it.
AGL - Above Ground Level, as a measurement of altitude above a
specific land mass, and differentiated from MSL.
AILERON - The movable areas of a wingform that control or affect
the roll of an aircraft by working opposite one anotherup-aileron
on the right wing and down-aileron on the left wing. French:
aileron small wing, diminutive of aile, from Latin: ala, wing. The
word "aisle" also derives from the same root. (Above pic proves
that birds invented ailerons long before man did.)
AIR DEFENSE IDENTIFICATION ZONE (ADIZ) - The area of airspace
over land or water, extending upward from the surface, within which
the ready identification, the location, and the control of aircraft
are required in the interest of national security.
Domestic Air Defense Identification Zone - An ADIZ within the
United States along an international boundary of the United
States.
Coastal Air Defense Identification Zone - An ADIZ over the
coastal waters of the United States.
Distant Early Warning Identification Zone (DEWIZ) - An ADIZ over
the coastal waters of the State of Alaska. ADIZ locations and
operating and flight plan requirements for civil aircraft
operations are specified in FAR Part 99.
AIRFOIL - The shape of any flying surface, but principally a
wing, as seen in side-view ("cross-section"). Its characteristics
are Center of Pressure (CP), DRAG (CD), LIFT (CL), Lift-Drag Ratio
(L/D), and Moment (CM).
AIR ROUTE TRAFFIC CONTROL CENTER (ARTCC) or "CENTER" - A
facility established to provide air traffic control service to
aircraft operating on IFR flight plans within controlled airspace
and principally during the en route phase of flight. When equipment
capabilities and controller workload permit, certain
advisory/assistance services may be provided to VFR aircraft.
AIR SPEED INDICATOR - An instrument or device that measures the
air speed of an aircraft through an air mass, but not its ground
speed.
AIR TAXI - An aircraft operator who conducts operations for hire
or compensation in accordance with FAR Part 135 in an aircraft with
30 or fewer passenger seats and a payload capacity of 7,500# or
less. An air taxi operates on an on demand basis and does not meet
the "flight scheduled" qualifications of a commuter.
AIR TRAFFIC CONTROL (ATC) - A service operated by the
appropriate authority to promote the safe, orderly, and expeditious
flow of air traffic.
AIRPORT TRAFFIC CONTROL TOWER (ATCT) - A terminal facility that
uses air/ground communications, visual signaling, and other devices
to provide ATC services to aircraft operating in the vicinity of an
airport or on the movement area. Authorizes aircraft to land or
takeoff at the airport controlled by the tower or to transit the
Class D airspace area regardless of flight plan or weather
conditions (IFR or VFR). A tower may also provide approach control
services (radar or non-radar).
ALCLAD - Trademark name of Alcoa for high-strength sheet
aluminum clad with a layer (approximately 5.5% thickness per side)
of high-purity aluminum, popularly used in airplane
manufacture.
ALPHABET (PHONETIC) - Devised for reasons of clarity in aviation
voice radio, this is the current NATO version in global use:
ALFA BRAVO CHARLEY DELTA ECHO FOXTROT GOLF
HOTEL INDIA JULIET KILO LIMA MIKE NOVEMBER
OSCAR PAPA QUEBEC ROMEO SIERRA TANGO
UNIFORM VICTOR WHISKY X-RAY YANKEE ZULU
The original, from early in World War 2, was:ABLE BAKER CHARLEY
DOG EASY FOX GEORGE
HOW ITEM JIG KING LOVE MIKE NAN OBOE
PETER QUEEN ROGER SUGAR TARE UNCLE VICTOR
WILLIAM X-RAY YOKE ZEBRA
ALTIMETER - An adjustable aneroid-barometic cockpit instrument
used to measure an aircraft's altitude.
AMPHIBIAN, AMPHIBION - A SEAPLANE or FLOATPLANE with retractable
wheels for use on land, as well. The latter spelling was used in
the '20s and '30s but has since fallen out of favor.
ANGLE OF ATTACK - The acute angle at which a moving airfoil
meets the airstream.
ANGLE OF INCIDENCE - The angle at which an airfoil is normally
fixed in relation to the longitudinal axis of an aircraft.
ANHEDRAL - The downward angle of a wing in relation to a
horizontal cross-section line; aka CATHEDRAL. SEE DIHEDRAL.
APPROACH CONTROL SEE RADIO NAVIGATION
APRON - The hard-surfaced or paved area around a hangar.
ARSA SEE CONTROLLED AIRSPACE
ARTIFICIAL HORIZON - A vacuum-powered panel instrument that
displays pitch and roll movements about the lateral and
longitudinal axes; aka Attitude Indicator.
ASPECT RATIO - The ratio of the span to the chord of an airfoila
high-aspect ratio wing has wide span and narrow chord, and
vice-versa.
ATA SEE CONTROLLED AIRSPACE
ATC - (1) Aircraft license as Approved Type Certificate, SEE
ATC; (2) AIR TRAFFIC CONTROL.
ATIS SEE AUTOMATIC TERMINAL INFORMATION SERVICE
AUTOGYRO, AUTOGIRO - An aircraft, often wingless, with unpowered
rotary airfoil blades that auto-rotate and serve as wings as it
moves through the air when driven by an engine. The latter spelling
is a trademark of the Autogiro Corporation.
AUTO-ROTATION - Automatic rotation of rotary blades from a
helicopter in an unpowered glide or the forward movement of an
autogyro.
AUTOMATIC TERMINAL INFORMATION SERVICE (ATIS) - Continuous
broadcast of recorded noncontrol information in selected terminal
areas, to improve controller effectiveness and to relieve frequency
congestion by automating repetitive transmissions of essential but
routine information.
BALANCED CONTROL SURFACE - A movable control surface, as an
aileron or rudder, having an added physical extension or weights
forward of the hinge-point to reduce forces on a joystick or yoke.
See ELEPHANT EARS (2).
BERNOULLI EFFECT (or LAW or THEOREM) - Since the pressure of a
fluid is proportional to its velocity, airflow over the upper
surface of an airfoil causes suction [lift] because the airstream
has been speeded up in relation to positive pressure of the airflow
on the lower surface.
BLEED AIR - Hot air at high pressure, usually from the bypass
section of a gas turbine engine, for de-icing, heating, and other
uses.
BOUNDARY-LAYER CONTROL - The design or control of slotted or
perforated wings with suction methods to reduce undesirable
aerodynamic effects caused by the boundary layer, that region
adjacent to the boundary where shear stresses dominate in the
airflow over a wingform.
BUMPED COWLING - An engine fairing, generally circular, with
welts or compound shapes in its surface to accommodate cylinder
heads.
CABANE STRUT - Wing strut attached to the fuselage.
CALIBRATED AIRSPEED (CAS) - The indicated air speed of an
aircraft, corrected for position and instrument error. CAS is equal
to true air speed in standard atmosphere at sea level. Compare
INDICATED AIRSPEED and TRUE AIRSPEED.
CAMBER - The convex or concave curvature of an airfoil.
CANARD - An arrangement in which the horizontal stabilizer and
elevators of an aircraft are mounted in front of the main
wing(s).
CAT - Clear-Air Turbulence.
CATHEDRAL SEE ANHEDRAL
CAVU - Ceiling and Visibility Unlimited; ideal flying
weather.
CEILING - (1) The heights above the earth's surface of the
lowest layer of clouds or obscuring phenomena that is reported as
"broken," "overcast," or "obscuration," and not classified as
"thin" or "partial". (2) The maximum height above sea level in
Standard Air attainable by an aircraft under given conditionsSEE
ABSOLUTE CEILING, SERVICE CEILING.
CENTER - An Air Route Traffic Control Center (ARTCC).
CENTER OF GRAVITY (c/g) - The longitudinal and lateral point in
an aircraft where it is stable; the static balance point.
CERTIFICATED AIRPORT - An airport operating under FAR Part 139.
The FAA issues airport operating certificates to all airports
serving scheduled or unscheduled air carrier aircraft designed for
more than 30 passenger seats. Certificated airports must meet
minimum safety standards in accordance with FAR Part 139.
CHORD - The measurable distance between the leading and trailing
edges of a wingform.
CLASS G AIRSPACE (Uncontrolled Airspace) - Airspace not
designated as Class A, B, C, D or E Controlled Airspace.
COAMING - A padded, protective rim around an open cockpit.
COLLECTIVE PITCH - A cockpit control that changes the pitch of a
helicopter's rotor blades; used in climbing or descending.
COLLECTOR RING - A circular duct on a radial engine into which
exhaust gases from its cylinders are discharged.
COMMON TRAFFIC ADVISORY FREQUENCY (CTAF) - A frequency designed
for the purpose of carrying out airport advisory practices while
operating to or from an airport without an operating control tower.
The CTAF may be a UNICOM, Multicom, FSS, or tower frequency and is
identified in appropriate aeronautical publications.
COMMUTER - An air carrier operator operating under 14 CFR 135
that carries passengers on at least five round trips per week on at
least one route between two or more points according to its
published flight schedules that specify the times, day of the week,
and places between which these flights are performed. The aircraft
that a commuter operates has 30 or fewer passenger seats and a
payload capability of 7,500# or less.
COMPASS COURSE - A bearing as indicated by the horizontal angle
between the compass needle and the centerline of the aircraft. A
Compass Course is equal to a True Course variation and deviation;
also equal to a Magnetic Course deviation.
COMPASS NORTH - The North point at which a liquid compass needle
points, rather than Geographical, or True, North. Compare MAGNETIC
NORTH.
CONE OF SILENCE SEE RADIO NAVIGATION
CONSTANT-SPEED PROPELLER - A hydraulically-controlled propeller
that governs an engine at its optimum speed by the blade pitch
being increased or decreased automatically.
CONTACT FLIGHT - Navigation in which altitude and flight path
can be maintained by visual reference to the ground and its
landmarks. Similar to VFR.
CONTOUR FLIGHT - Contact Flight in and around mountainous areas
following visual reference to the terrain's countours.
CONTRAILS - Streaks of condensed water vapor created in the air
by aircraft flying at high altitudes; aka Vapor Trails.
CONTROLLED AIRSPACE - An airspace of defined dimensions within
which air traffic control service is provided to IFR flights and to
VFR flights in accordance with the airspace classification.
Controlled airspace is a generic term that covers Class A, B, C, D,
and E airspace. Controlled airspace is also that airspace within
which all aircraft operators are subject to certain pilot
qualifications, operating rules, and equipment requirements in FAR
Part 91. For IFR operations in any class of controlled airspace, a
pilot must file an IFR flight plan and receive an appropriate ATC
clearance. Each B, C, and D airspace area designated for an airport
contains at least one primary airport around which the airspace is
designated (for specific designations and descriptions of the
airspace classes, refer to FAR Part 71.
Class A (formerly PCA - Positive Control Area) generally, that
airspace from 18,000' mean sea level (MSL) up to and including
flight level (FL) 600 (60,000' pressure altitude), including the
airspace overlying the waters within 12 nautical miles of the coast
of the 48 contiguous States and Alaska. Unless otherwise
authorized, all persons must operate their aircraft under IFR.
Class B (formerly TCA - Terminal Control Area) Generally, that
airspace from the surface to 10,000' MSL surrounding the nation's
busiest airports in terms of airport operations or passenger
enplanements. The configuration of each Class B airspace area is
individually tailored and consists of a surface area and two or
more layers (some Class B airspace areas resemble upside-down
wedding cakes), and is designed to contain all published instrument
procedures once an aircraft enters the airspace. An ATC clearance
is required for all aircraft to operate in the area, and all
aircraft that are so cleared receive separation services within the
airspace. The cloud clearance requirement for VFR operations is
"clear of clouds."
Class C (formerly ARSA - Airport Radar Service Area) Generally,
that airspace from the surface to 4,000' MSL above the airport
elevation surrounding those airports that have an operational
control tower, are serviced by a radar approach control, and that
have a certain number of IFR operations or passenger enplanements.
Although the configuration of each Class C area is individually
tailored, the airspace usually consists of a surface area with a 5
nautical mile (nm) radius, an outer circle with a 10 nm radius that
extends from 1,200' to 4,000' above the airport elevation and an
outer area. Each person must establish two-way radio communications
with the ATC facility providing air traffic services prior to
entering the airspace and thereafter maintain those communications
while within the airspace. VFR aircraft are only separated from IFR
aircraft within the airspace.
Class D (formerly ATA - Airport Traffic Area and CZ - Control
Zone) Generally, that airspace from the surface to 2,500' MSL above
the airport elevation surrounding those airports that have an
operational control tower. The configuration of each Class D
airspace area is individually tailored and when instrument
procedures are published, the airspace will normally be designed to
contain the procedures. Arrival extensions for instrument approach
procedures may be Class D or E airspace. Unless otherwise
authorized, each person must establish two-way radio communications
with the ATC facility providing air traffic services prior to
entering the airspace and thereafter maintain those communications
while in the airspace. No separation services are provided to VFR
aircraft.
Class E (formerly General Controlled Airspace) Generally, if the
airspace is not Class A, B, C, or D, and is controlled airspace, it
is Class E airspace. Class E airspace extends upward from either
the surface or a designated altitude to the overlying or adjacent
controlled airspace. When designated as a surface area, the
airspace will be configured to contain all instrument procedures.
Also in this class are Federal airways, airspace beginning at
either 700' or 1,200' AGL used to transition to/from the terminal
or enroute environment, enroute domestic, and offshore airspace
areas designated below 18,000' MSL. Unless designated at a lower
altitude, Class E airspace begins at 14,500' MSL over the USA,
including that airspace overlying the waters within 12 nautical
miles of the coast of the 48 contiguous States and Alaska, up to,
but not including 18,000' MSL, and the airspace above Flight Level
600.
CONVENTIONAL GEAR - Having two main landing wheels at the front
and a tailwheel or tailskid at the rear as opposed to having a
tricycle gear with three main wheels. Such an aircraft is popularly
called a TAILDRAGGER.
COWL, COWLING - A circular, removable fairing around an aircraft
engine (generally radial) for the purposes of streamling or
cooling; aka RING COWLING.
COWL FLAP - A controllable louvre to regulating airflow through
an engine's cowling.
CRAB - A rudder-controlled yawing motion to compensate for a
crosswind in maintaining a desired flight path, as in a landing
approach.
CTAF SEE COMMON TRAFFIC ADVISORY FREQUENCY
DEADSTICK - Descending flight with engine and propeller
stopped.
DECALAGE - The difference in angular settings [Angles of Attack]
of the wings of a biplane or multiplane.
DECISION HEIGHT - With respect to the operation of aircraft, the
height at which point a decision must be made during an instrument
approach to either continue the approach or to execute a missed
approach [abort].
DELTA-WING - A triangularly-shaped aircraft wing having a low
aspect ratio, a sharply-tapered leading edge, a straight trailing
edge, and a pointed tip.
DEPARTURE CONTROL SEE RADIO NAVIGATION
DEPARTURE STALL - A stall in the takeoff configuration with
power.
DEVIATION (MAGNETIC) - The error of a Magnetic Compass due to
inherent magnetic influences in the structure and equipment of an
aircraft.
DEWIZ SEE AIR DEFENSE IDENTIFICATION ZONE
DIHEDRAL - The acute angle, usually upward, between the wing of
an airplane and a horizontal cross-section line. Opposite of
ANHEDRAL.
DIRECTIONAL GYRO - A panel instrument providing a gyroscopic
reading of an aircraft's compass heading.
DIRIGIBLE - A lighter-than-air craft capable of being propelled
and steered for controlled flight. Latin: dirigo,to steer.
DME - Distance Measuring Equipment, a radio navigation device
that determines an aircraft's distance from a given ground station,
as well as its groundspeed and time to/from the station.
DORSAL FIN - A lateral fin/rudder extension on the top of a
fuselage.
DOWNWASH - The air deflected perpendicular to the direction of
movement of an airfoil.
DRAG - The resisting force exerted on an aircraft in its line of
flight opposite in direction to its motion. Compare THRUST.
DRAG WIRE - A wire designed to resist DRAG forces, usually
running from a forward inboard point to an outboard aft point.
DRIFT - The angle between the heading of an aircraft and its
Track, or flight path, over the ground as affected by winds.
DRY WEIGHT - The weight of an engine exclusive of any fuel, oil,
and coolant.
DURAL - Originally a tradename for a wrought aluminum-copper
alloy created by Bausch Machine Tool Co, now fallen into generic
use as any aluminum alloy containing 3.0-4.5% copper, 0.4-1.0%
magnesium, and 0.1-0.7% manganese. Alcoa's version is commonly
referred to as "Duraluminum," popularly used in aircaft
manufacture.
EARTH-INDUCTOR COMPASS - One whose indications depend on the
current generated in a coil revolving in the earth's magnetic
field.
ELEPHANT EAR - (1) An air intake characterized by twin inlets,
one on each side of the fuselage. (2) A type of balanced aileron in
which the outer edges are noticeably larger than the control
itself. See BALANCED CONTROL SURFACE and example Travel Air
4000.
ELEVATOR - The movable part of a horizontal airfoil which
controls the pitch of an aircraft; the fixed part being the
STABILIZER.
ELEVON - A hinged device on the rear portion of an aircraft wing
combining the functions of an elevator and an aileron. Usually
found on delta-wing aircraft, it can be moved in the same direction
on either side of the aircraft to obtain longitudinal control, or
differentially to obtain lateral control. Also see FLAPERON.
ELT - Emergency Locator Transmitter
EMPENNAGE - An aircraft's tail group, includes rudder and fin,
and stabilizer and elevator. Old French: empenner,to feather an
arrow, from Latin penna, feather. Other words derived from the same
root are panache, pen, pin, pinnacle, and pennant.
EN ROUTE AIR TRAFFIC CONTROL SERVICES - Air traffic control
services provided aircraft on IFR flight plans, generally by
centers, when these aircraft are operating between departure and
destination terminal areas. When equipment, capabilities, and
controller workload permit, certain advisory/assistance services
may be provided to VFR aircraft.
ETA - Estimated Time of Arrival.
ETD - Estimated Time of Departure.
FAIRING - An added streamlining structure or auxiliary member,
most often of light metal, whose only purpose is to reduce drag.
Fairings are not load-bearing and, therefore, are not meant to
carry any principal air loads placed on the airplane structure.
FBO - Fixed-Base Operator, a commercial operator supplying fuel,
maintenance, flight training, and other services at an airport.
FAN MARKER SEE RADIO NAVIGATION
FEATHERING - In the event of engine failure, the process of
adjusting a controllable-pitch propeller to a pitch position where
the blade angle is about 90 to the plane of rotation in order to
stop windmilling.
FEDERAL AIR REGULATION (FAR)
FAR Part 91 - General Aviation (portions apply to all
operators)
FAR Part 103 - Ultralight Vehicles
FAR Part 105 - Parachute Jumping
FAR Part 108 - Airplane Operator Security
FAR Part 119 - Certification: Air Carriers and Commercial
Operators
FAR Part 121 - Domestic, Flag, and Supplemental Air Carriers and
Commercial Operators of Large Aircraft
FAR Part 123 - Travel Clubs
FAR Part 125 - US Civil Airplanes, seating 20 or more passengers
or a maximum payload capacity 6,000# or more
FAR Part 127 - Air Carriers using helicopters for scheduled
interstate flights (within the 48 contiguous states)
FAR Part 129 - Foreign Air Carrier and Foreign Operators of US
registered aircraft engaged in common carriage
FAR Part 133 - Rotorcraft External Load Operations
FAR Part 135 - Air Taxi Operators and Commercial Operators
FAR Part 137 - Agricultural Aircraft Operations
FAR Part 141 - Pilot School
FERRY FLIGHT - A flight for the purpose of (1) returning an
aircraft to base; (2) delivering an aircraft from one location to
another; (3) moving an aircraft to and from a maintenance base.
Ferry flights, under certain conditions, may be conducted under
terms in a special flight permit.
FIN - The fixed part of a vertical airfoil that controls the yaw
of an aircraft; the movable part being the RUDDER. Sometime
referred to as Vertical Stabilizer.
FIREWALL - A fire-resistant bulkhead that isolates the engine
from other parts of an airplane's structure.
FISHTAILING - A rudder-controlled side-to-side [yawing] motion
to reduce air speed, generally prior to landing.
FIVE-BY-FIVE (5x5) - In radio jargon, affirms that a radioed
transmission was received clear and loud. Rated one to five, with
the first figure for clearness and the second second for
loudness.
FLAP - A movable, usually hinged AIRFOIL set in the trailing
edge of an aircraft wing, designed to increase LIFT or DRAG by
changing the CAMBER of the wing or used to slow an aircraft during
landing by increasing lift. Also see FOWLER FLAP, SLOTTED FLAP, and
SPLIT FLAP.
FLAPERON - A control surface combining the functions of a FLAP
and an AILERON.
FLARE - A maneuver performed moments before landing in which the
nose of an aircraft is pitched up to minimize the touchdown rate of
speed.
FLIGHT ENVELOPE - An aircraft's performance limits, specifically
the curves of speed plotted against other variables to indicate the
limits of speed, altitude, and acceleration that a particular
aircraft can not safely exceed.
FLIGHT LEVEL (FL) - A level of constant atmospheric pressure
related to a reference datum of 29.92 inches of mercury. Each is
stated in three digits that represent hundreds of feetflight level
250 represents a barometric altimeter indication of 25,000', flight
level 255 an indication of 25,500'.
FLIGHT PLAN - Specified information relating to the intended
flight of an aircraft that is filed orally or in writing with an
FSS or an ATC facility.
FLIGHT SERVICE STATION (FSS) - Air traffic facilities which
provide pilot briefing, enroute communications and VFR search and
rescue services, assist lost aircraft and aircraft in emergency
situations, relay ATC clearances, originate Notices to Airmen,
broadcast aviation weather and NAS information, receive and process
IFR flight plans, and monitor NAVAIDs. In addition, at selected
locations, FSSs provide Enroute Flight Advisory Service (Flight
Watch), take weather observations, issue airport advisories, and
advise Customs and Immigration of transborder flights.
FLOATPLANE - A water-based aircraft with one or more mounted
pontoons, as differentiated from a hulled SEAPLANE or Flying Boat,
but sometimes used generically.
FLYING WIRES - Interplane bracing wires that help support
wingloads when the plane is in flight. Direction of travel is
upward and outward from the fuselage to the interplane struts. Also
known as LIFT WIRES, the opposite of LANDING WIRES.
FOWLER FLAP - Trademark name of a split-flap attached to a wing
through a system of tracks and rollers to roll the flap backward
and downward, increasing the wing area.
FRISE AILERON - A type of aileron that has a beveled leading
edge projecting beyond its inset hinges. When lowered, it forms an
extension of the wing surface; when raised, its nose protrudes
below the wing, increasing DRAG and reducing YAW. Named after its
inventor, British engineer Leslie George Frise.
FSS SEE FLIGHT SERVICE STATION
FUSELAGE - An aircraft's main body structure housing the flight
crew, passengers, and cargo and to which the wings, tail and, in
most single-engined airplanes, engine are attached. French: fusel,
tapering.
g or G SEE LOAD FACTOR
GAP - The distance between two adjacent wings of a biplane or
multiplane.
GCA - Ground-Controlled Approach; part of ILS.
GENERAL AVIATION - That portion of civil aviation which
encompasses all facets of aviation except air carriers holding a
certificate of public convenience and necessity from the Civil
Aeronautics Board and large aircraft commercial operators.
GEOGRAPHIC NORTH - The northern axis around which the Earth
revolves; aka "Map North" and TRUE NORTH. Also see MAGNETIC NORTH,
TRUE NORTH.
GLASS COCKPIT - Said of an aircraft's control cabin which has
all-electronic, digital and computer-based, instrumentation.
GLIDER - An unpowered aircraft capable of maintaining altitude
only briefly after release from tow, then gliding to earth. Compare
SAILPLANE.
GLIDE SLOPE - (1) The angle between horizontal and the glide
path of an aircraft. (2) A tightly-focused radio beam transmitted
from the approach end of a runway indicating the minimum approach
angle that will clear all obstacles; one component of an instrument
landing system (ILS).
GPS - Global Positioning System; satellite-based navigation.
GREEN LIGHT - Approval for landing. A carryover expression from
days when aircraft for the most part had no radios, and
communication from a control tower was by means of a light-gun that
beamed various green, red, and yellow signals to pilots in the air
and on the ground.
GROSS WEIGHT - The total weight of an aircraft when fully
loaded; aka Takeoff Weight.
GROUND CONTROL - Tower control, by radioed instructions from air
traffic control, of aircraft ground movements at an airport.
GROUND CUSHION SEE GROUND EFFECT
GROUND EFFECT - Increased lift generated by the interaction
between a lift system and the ground when an aircraft is within a
wingspan distance above the ground. It affects a low-winged
aircraft more than a mid- or high-winged aircraft because its wings
are closer to the ground; aka GROUND CUSHION.
GROUND SPEED - The actual speed that an aircraft travels over
the groundits "shadow speed"; it combines the aircraft's AIR SPEED
and the wind speed relative to the aircraft's direction of
flight.
GULL-WING - Descriptive of wing in frontal view bent as the wing
of a seagull; a distinctive shallow, inverted "V" shapesee Stinson
SR-7 or inverted gull-wing Vought F4U.
GYROPLANE - A rotorcraft whose rotors are not engine-driven,
except for initial starting, but are made to rotate by action of
the air when the rotorcraft is moving and whose means of
propulsion, usually a conventional propeller, is independent of the
rotor system. Similar to AUTOGYRO.
HANGAR - An enclosed structure for housing aircraft. Originated
with lake-based floating homes of the original German Zeppelins in
which they were "hung" from cables, which explains the erroneous,
oft-seen spelling of "hanger." French: shed, outbuilding, from
Latin: angarium, shed.
HELICOPTER - A wingless aircraft acquiring its lift from
revolving blades driven by an engine about a near-vertical axis. A
ROTORCRAFT acquiring its primary motion from engine-driven rotors
that accelerate the air downward, providing a reactive lift force,
or accelerate the air at an angle to the vertical, providing lift
and thrust.
HIGH BLOWER - A blower-type supercharger set at high rpm.
HIGH-SPEED STALL - Any stall made to occur at more than 1g, such
as pulling out of a dive or while turning.
HORSEPOWER - The motive energy required to raise 550# one foot
in one second, friction disregarded.
HYPERSONIC - Speed of flight at or greater than Mach 5.0,
exceeding SUPERSONIC.
IFR - Instrument Flight Rules, governing flight under instrument
meteorological conditions.
ILS - Instrument Landing System. A radar-based system allowing
ILS-equipped aircraft to find a runway and land when clouds may be
as low as 200 feet (or lower for special circumstances).
INDICATED AIRSPEED (IAS) - A direct instrument reading obtained
from an air speed indicator uncorrected for altitude, temperature,
atmospheric density, or instrument error. Compare CALIBRATED
AIRSPEED and TRUE AIRSPEED.
INSTRUMENT METEOROLOGICAL CONDITIONS (IMC) - Meteorological
conditions expressed in terms of visibility, distance from clouds,
and ceiling less than minima specified for visual meteorological
conditions (VMC).
IRON COMPASS - Railroad tracks, as favored by pilots of yore as
a dependable aid to surface navigation.
JOYSTICK - A single floor- or roof-mounted control sticksideways
movement produces ROLL, and forward/backward movement produces
PITCH (rudder pedals produce YAW).
KNOT - One nautical mile, about 1.15 statute miles (6,080'); eg:
125kts = 143.9mph.
LAMINAR-FLOW AIRFOIL - A low-drag airfoil designed to maintain
laminar flow over a high percentage of the chord about itself.
Often relatively thin, especially along the leading edge, with most
of its bulk near the center of the chord.
LANDING WIRES - Interplane bracing wires that help support
wingloads when the plane is on the ground. Direction of travel is
downward and outward from the fuselage. Opposite of FLYING
WIRES.
LIFT - The force exerted on the top of a moving airfoil as a
low-pressure area that causes a wingform to rise.
LIFT-DRAG RATIO - The lift coefficient of a wing divided by the
drag coefficient, as the primary measure of the efficiency of an
aircraft; aka L/D Ratio.
LIFT WIRES - Interplane bracing wires that help support
wingloads when the plane is in flight. Direction of travel is
upward from the bottom of the fuselage to the top of the interplane
struts. Also known as FLYING WIRES, the opposite of LANDING
WIRES.
LIGHT SPORT AIRCRAFT - Special FAA certification class (LSA) for
an aircraft other than a helicopter or powered-liftsingle-engine
aircraft, airship, balloon, GLIDER, GYROCOPTER, ROTORCRAFT,
weight-shift-control aircraft. While limiting the types of aircraft
that could be flown by a Sport Pilot, it simplified requirements
for a obtaining a pilot license and did not require a medical
examination. SEE LSA feature.
LIQUID COMPASS - A non-electronic, calibratable compass floating
in a liquid as a panel instrument; aka Wet Compass.
LOAD FACTOR (g) - The proportion between lift and weight
commonly seen as g (sometimes capitalized)a unit of force equal to
the force of gravity times one.
LOFTING - Design or fabrication of a complex aircraft component,
as with sheet metal, using actual-size patterns or plans, generally
laid out on a floor. The term is borrowed from boat builders.
LONGERON - A principal longitudinal member of a fuselage's
framing, usually continuous across a number of supporting
points.
LOOP ANTENNA - A circular radio antenna, either in the open or
in a streamlined, teardrop housing, remotely turned 360 to
fine-tune a station in league with other radio-directive devices.
See also RADIO COMPASS, RADIO DIRECTION FINDER.
LORAN - Long Range Navigation system, which utilizes timing
differences between multiple low-frequency transmissions to provide
accurate latitude/longitude position information to within 50'.
LTA - Lighter-than-air craft, generally referring to powered
blimps and dirigibles, but often also includes free balloons.
LUNKENHEIMER VALVE - A manual fuel drain placed handily along a
fuel line for checking avgas, such as for water or sediment
contaminations.
Mach or m. - A number representing the ratio of the speed of an
object to the speed of sound in the surrounding air or medium in
which it is moving.
MAGNETIC COMPASS - The most common liquid-type compass, capable
of calibration to compensate for magnetic influences within the
aircraft.
MAGNETIC COURSE - COMPASS COURSE deviation.
MAGNETIC NORTH - The magnetic North pole, located near 71 North
latitude and 96 West longitude, that attracts a magnetic compass
which is not influenced by local magnetic attraction, as opposed to
GEOGRAPHIC NORTH.
MAGNETO, MAG - An accessory that produces and distributes a
high-voltage electric current for ignition of a fuel charge in an
internal combustion engine.
MAGNUS EFFECT - The effect on a spinning cylinder or sphere
moving through a fluid, in which force acts perpendicular to the
direction of motion and to the direction of spin. This is used to
advantage in baseball, in which the trajectory of a pitched ball is
a distinct curve. Applied to aeronautics in experimental wingforms,
the Magnus Theory states that if air is directed against a smooth,
revolving cylinder, whose circumferential speed is greater than
that of the air current, a force is directed against one side of
the cylinderair compressed on one side and vacuum formed on the
othercreating lift. Named after physicist Heinrich Gustav Magnus
(1802-70).
MARKER BEACON SEE RADIO NAVIGATION
MEAN SEA LEVEL SEE MSL
METAR - Acronym in FAA pilot briefings and weather reports
simply means an "aviation routine weather report," but nobody seems
certain about the original source. The format was introduced by the
French on 1 Jan 1968, but was not adopted by USA and Canada until 1
July 1996, and is thought to be a contraction from MTorologique
("Weather") Aviation Rgulire ("Routine"). FAA and NOAA specifically
define METAR as "an approximate translation from the French."
MOA SEE SPECIAL USE AIRSPACE
MONOCOQUE - Type of fuselage design with little or no internal
bracing other than bulkheads, where the outer skin bears the main
stresses; usually round or oval in cross-section. Additional
classifications are (1) Semi-Monocoque, where the skin is
reinforced by longerons or bulkheads, but with no diagonal web
members, and (2) Reinforced Shell, in which the skin is supported
by a complete framework or structural members. French:
monocoque,single shell.
MSL - Mean Sea Level. The average height of the surface of the
sea for all stages of tide; used as a reference for elevations, and
differentiated from AGL.
NACELLE - A streamlined enclosure or housing to protect
something such as the crew, engine, or landing gear. French:
nacelle,from Latin, navicella,little ship.
NATIONAL AIRSPACE SYSTEM (NAS) - The common network of US
airspace; air navigation facilities, equipment and services,
airports or landing areas; aeronautical charts, information and
services; rules, regulations and procedures, technical information,
and human resources and material. Included are system components
shared jointly with the military.
NDB - Non-Directional Beacon. An LF, MF, or UHF radio beacon
transmitting non-directional signals whereby the pilot of an
aircraft equipped with direction finding equipment can determine
his bearing to or from the radio beacon and "home" on or track to
or from the station. When the radio beacon is installed in
conjuncion with the Instrument Landing System (ILS) marker, it is
normally called a Compass Locator.
OVERSHOOT - To land well beyond a runwway or planned spot.
Opposite of UNDERSHOOT.
PANTS - A popular word for streamlined, non-load bearing
fairings to cover landing wheels. Also sometimes called Spats or,
when fully enclosing the wheel struts, Skirts.
PAR - Precision Approach Radar, a ground-radar-based instrument
approach providing both horizontal and vertical guidance
PATTERN - The path of aircraft traffic around an airfield, at an
established height and direction. At tower-controlled fields the
pattern is supervised by radio (or, in non-radio or emergency
conditions by red and green light signals) by air traffic
controllers.
PAYLOAD - Anything that an aircraft carries beyond what is
required for its operation during flight, theoretically that from
which revenue is derived, such as cargo and passengers.
PCA SEE CONTROLLED AIRSPACE
PHONETICS SEE ALPHABET
PILOT IN COMMAND (PiC) - The pilot responsible for the operation
and safety of an aircraft during flight time.
PITCH - (1) Of the three axes in flight, this specifies the
vertical action, the up-and-down movement. Compare ROLL and YAW.
(2) The angle of a propeller or rotor blade in relation to its arc;
also the distance advanced by a blade in one full rotation.
PITOT TUBE - More accurately but less popularly used,
Pitot-Static Tube, a small tube most often mounted on the outward
leading edge of an airplane wing (out of the propeller stream) that
measures the impact pressure of the air it meets in flight, working
in conjuction with a closed, perforated, coaxial tube that measures
the static pressure. The difference in pressures is calibrated as
air speed by a panel instrument. Named after French scientist Henri
Pitot (1695-1771).
POSITIVE CONTROL - The separation of all air traffic within
designated airspace by air traffic control.
POWER LOADING - The GROSS WEIGHT of an airplane divided by the
rated horsepower, computed for Standard Air density.
PUSHER - A propeller mounted in back of its engine, pushing an
aircraft through the air, as opposed to a TRACTOR
configuration.
QUADRAPLANE, QUADRUPLANE - An aircraft having four or more
wingforms.
RADAR APPROACH CONTROL FACILITY (RAPCON) - A terminal ATC
facility that uses radar and non-radar capabilities to provide
approach control services to aircraft arriving, departing, or
transiting airspace controlled by the facility. This facility
provides radar ATC services to aircraft operating in the vicinity
of one or more civil/military airports in a terminal area. The
facility may provide services of a ground-controlled approach
(GCA). A radar approach control facility may be operated by FAA or
a military service, or jointly. Specific facility nomenclatures are
used for administrative purposes only and are related to the
physical location of the facility and the operating service
generally:
Army Radar Approach Control (ARAC) (Army)
Radar Air Traffic Control Facility (RATCF) (Navy/FAA)
Radar Approach Control (RAPCON) (Air Force/FAA)
Terminal Radar Approach Control (TRACON) (FAA)
Tower/Airport Traffic Control Tower (ATCT) (FAA only towers
delegated approach control authority)
RADIO COMPASS SEE RADIO NAVIGATION
RAMJET - An aerodynamic duct in which fuel is burned to produce
a high-velocity propulsive jet. It needs to be accelerated to high
speed before it can become operative.
RING COWLING - A circular engine FAIRING.
ROGALLO WING - A flexible, delta-wing plan in which three rigid
members are shaped in the form of an arrowhead and joined by a
flexible fabric, which inflates upward under flight loads.
Originally specific to paragliders, but now found on some powered
aircraft.
ROLL - Of the three axes in flight, this specifies the action
around a central point. Compare PITCH and YAW.
ROTARY ENGINE - A powerplant that rotates on a stationary
propeller shaft. An American invention by Adams-Farwell Co (1896),
it was first used for buses and trucks in the US (1903), then
copied by French engineers for early aircraft engines (1914).
ROTORCRAFT - A heavier-than-air aircraft that depends
principally for its support in flight on the lift generated by one
or more rotors. Includes helicopters and gyroplanes.
RUDDER - The movable part of a vertical airfoil which controls
the YAW of an aircraft; the fixed part being the FIN.
SAILPLANE - An unpowered, soaring aircraft capable of
maintaining level flight for long periods of time after release
from tow and of gaining altitude using wind currents, as opposed to
a GLIDER.
SCRAMJET - Acronym for supersonic combustion ramjet, in which
combustion occurs at supersonic air velocities through the
engine.
SCUD - A low, foglike cloud layer.
SEAPLANE - A water-based aircraft with a boat-hull fuselage,
often amphibious.The term is also used generically to define a
similar Flying Boat and a pontoon FLOATPLANE.
SECONDARY STALL - Any stall resulting from pulling back too soon
and too hard while recovering from any other stall. Usually a
HIGH-SPEED or ACCELERATED STALL.
SERVICE CEILING - The height above sea level at which an
aircraft with normal rated load is unable to climb faster than 100'
per minute under Standard Air conditions.
SESQUI-WING - A lesser-span additional wingform, generally
placed below the main planes of an aircraft, generally a
biplane.
SHOULDER-WING - A mid-wing monoplane with its wing mounted
directly to the top of the fuselage without use of CABANE
STRUTs.
SIDESLIP - A movement of an aircraft in which a relative flow of
air moves along the lateral axis, resulting in a sideways movement
from a projected flight path, especially a downward slip toward the
inside of a banked turn.
SINK, SINKING SPEED - The speed at which an aircraft loses
altitude, especially in a glide in still air under given conditions
of equilibrium.
SKID - Too shallow a bank in a turn, causing an aircraft to
slide outward from its ideal turing path.
SLATS - Movable vanes or auxiliary airfoils, usually set along
the leading edge of a wing but able to be lifted away at certain
angles of attack.
SLIP - Too steep a bank in a turn, causing an aircraft to slide
inward from its ideal turing path.
SLIPSTREAM - The flow of air driven backward by a propeller or
downward by a rotor.
SLOT - A long, narrow, spanwise gap in a wing, usually near the
leading edge, to improve airflow at high angles of attack for
slower landing speeds.
SLOTTED FLAP - A flap that, when depressed, exposes a slot and
increases airflow between itself and the rear edge of the wing.
SMOH - "Since Major Overhaul," an acronym seen in reference to
the operating hours, or time remaining, on an engine.
SPECIAL USE AIRSPACE (SUA) - Airspace of defined dimensions
identified by an area on the surface of the earth wherein
activities must be confined because of their nature and/or wherein
limitations may be imposed upon aircraft operations that are not a
part of those activities:
Alert Area - Airspace which may contain a high volume of pilot
training activities or an unusual type of aerial activity, neither
of which is hazardous to aircraft. Alert Areas are depicted on
aeronautical charts for the information of non-participating
pilots. All activities within an Alert Area are conducted in
accordance with Federal Aviation Regulations, and pilots of
participating aircraft as well as pilots transiting the area are
equally responsible for collision avoidance.
Military Operations Area (MOA) - Airspace established outside of
Class A airspace area to separate or segregate certain
non-hazardous military activities from IFR traffic and to identify
for VFR traffic where these activities are conducted.
Prohibited Area - Airspace designated under part 73 within which
no person may operate an aircraft without the permission of the
using agency.
Restricted Area - Airspace designated under FAR Part 73, within
which the flight of aircraft, while not wholly prohibited, is
subject to restriction. Most restricted areas are designated joint
use and IFR/VFR operations in the area may be authorized by the
controlling ATC facility when it is not being utilized by the using
agency. Restricted areas are depicted on enroute charts. Where
joint use is authorized, the name of the ATC controlling facility
is also shown.
Warning Area - A warning area is airspace of defined dimensions
extending from 3 nautical miles outward from the coast of the USA,
that contains activity that may be hazardous to non-participating
aircraft. The purpose of such warning area is to warn
non-participating pilots of the potential danger. A warning area
may be located over domestic or international waters or both.
SPLIT FLAP - A FLAP built into the underside of a wing, as
opposed to a Full Flap wherein a whole portion of the trailing edge
is used.
SPOILER - A long, movable, narrow plate along the upper surface
of an airplane wing used to reduce lift and increase drag by
breaking or spoiling the smoothness of the airflow.
SPORT PILOT - Special FAA certification enabling "budget"
pilotry; see LIGHT SPORT AIRCRAFT and LSA feature.
SPONSON - A short, winglike protuberance on each side of a
seaplane to increase lateral stability.
SQUAWK - A four-digit number which is dialed into his
transponder by a pilot to identify his aircraft to air traffic
controllers
STABILATOR - A movable horizontal tail that combines the actions
of a stabilizer and elevator, increasing longitudinal stability
while creating a pitching moment.
STABILIZER - The fixed part of a horizontal airfoil that
controls the pitch of an aircraft; the movable part being the
ELEVATOR.
STAGGER - The relative longitudinal position of the wings on a
biplane. Positive Stagger is when the upper wing's leading edge is
in advance of that of the lower wing [eg: Waco YKS], and vice versa
for Negative Stagger [eg: Beechcraft D17].
STALL - (1) Sudden loss of lift when the angle of attack
increases to a point where the flow of air breaks away from a wing
or airfoil, causing it to drop. (2) A maneuver initiated by the
steep raising of an aircraft's nose, resulting in a loss of
velocity and an abrupt drop.
STANDARD AIR (Standard Atmosphere) - An arbitrary atmosphere
established for calibration of aircraft instruments. Standard Air
Density is 29.92 inches of mercury and temperature of 59 F,
equivalent to an atmospheric air pressure of 14.7# per square
inch.
STANDARD RATE TURN - A turn in which the heading of an aircraft
changes 3 per second, or 360 in two minutes.
STATIC WIRE - A clip-on wire used to ground an aircraft by
drawing off static electricity, a potential fire hazard, during
refueling.
SUA SEE SPECIAL USE AIRSPACE
SUPERSONIC - Speed of flight at or greater than Mach 1.0;
literally, faster than the speed of sound.
SWEEPBACK - A backward inclination of an airfoil from root to
tip in a way that causes the leading edge and often the trailing
edge to meet relative wind obliquely, as wingforms that are swept
back.
SWING-WING - A wing whose horizontal angle to the fuselage
centerline can be adjusted in flight to vary aircraft motion at
differing speeds.
TAILDRAGGER SEE CONVENTIONAL GEAR
TARMAC - (1) A bituminous material used in paving; a trade name
for Tar MacAdam. (2) An airport surface paved with this substance,
especially a runway or an APRON at a hangar.
TAS - True Air Speed. Because an air speed indicator indicates
true air speed only under standard sea-level conditions, true air
speed is usually calculated by adjusting an Indicated Air speed
according to temperature, density, and pressure. Compare CALIBRATED
AIR SPEED and INDICATED AIR SPEED.
TCA SEE CONTROLLED AIRSPACE
TERMINAL RADAR SERVICE AREA (TRSA) - Airspace surrounding
designated airports wherein ATC provides radar vectoring,
sequencing, and separation on a full-time basis for all IFR and
participating VFR aircraft. Service provided at a TRSA is called
Stage III Service. TRSAs are depicted on VFR aeronautical charts.
Pilot participation is urged but is not mandatory.
TETRAHEDRON - Ground-based, free-rotating, triangular-shaped
wind direction indicator, genrally placed near a runway.
THRUST - The driving force of a propeller in the line of its
shaft or the forward force produced in reaction to the gases
expelled rearward from a jet or rocket engine. Opposite of
DRAG.
TORQUE - A twisting, gyroscopic force acting in opposition to an
axis of rotation, such as with a turning propeller; aka
Torsion.
TOUCH-AND-GO - Landing practice wherein an aircraft does not
make a full stop after a landing, but proceeds immediately to
another take-off.
TRACTOR - A propeller mounted in front of its engine, pulling an
aircraft through the air, as opposed to a PUSHER configuration.
TRAILING EDGE - The rearmost edge of an AIRFOIL.
TRANSPONDER - An airborne transmitter that responds to
ground-based interrogation signals to provide air traffic
controllers with more accurate and reliable position information
than would be possible with "passive" radar; may also provide air
traffic control with an aircraft's altitude.
TRIKE - Nickname for a weight-shift-control aircraft, such as a
paraglider.
TRIM TAB - A small, auxiliary control surface in the trailing
edge of a wingform, adjustable mechanically or by hand, to
counteract ("trim") aerodynamic forces on the main control
surfaces.
TRUE AIRSPEED - The speed of an aircraft along its flight path,
in respect to the body of air (air mass) through which the aircraft
is moving. Also see CALIBRATED AIRSPEED, GROUND SPEED, INDICATED
AIRSPEED.
TRUE NORTH - The northern direction of the axis of the Earth;
aka "Map North." GEOGRAPHIC NORTH, as opposed to MAGNETIC
NORTH.
TURBOJET - An aircraft having a jet engine in which the energy
of the jet operates a turbine that in turn operates the air
compressor.
TURBOPROP - An aircraft having a jet engine in which the energy
of the jet operates a turbine that drives the propeller.
ULTRALIGHT - An aeronautical vehicle operated for sport or
recreational purposes which does not require FAA registration, an
airworthiness certificate, nor pilot certification. Primarily
single-occupant vehicles, although some two-place vehicles are
authorized for training purposes. Operation of an ultralight
vehicle in certain airspaces requires authorization from ATC.
UNCONTROLLED AIRSPACE - Class G Airspace; airspace not
designated as Class A, B, C, D or E.
UNDERCARRIAGE - The landing gear of a land-based aircraft,
including struts, frames, and wheels.
UNDERSHOOT - To land short of a runwway or planned landing spot.
Opposite is OVERSHOOT.
UNICOM - Universal Communication. A common radio frequency
(usually 121.0 mHz) used at uncontrolled (non-tower) airports for
local pilot communication.
UPWASH - The slight, upward flow of air just prior to its
reaching the leading edge of a rapidly moving airfoil.
UPWIND TURN - Long a point of contest among pilots, there is in
reality no such thing as far as the airplane is concerned.
Proponents claim that airplanes lose air speed when turning upwind,
while opponents (and the laws of physics) argue that an airplane,
like a boat in a river whose speed is only relative to the water
and not the shore, is unaffected within the movement of an air mass
and that it loses only ground speed.
USEFUL LOAD - The weight of crew, passengers, fuel, baggage, and
ballast, generally excluding emergency or portable equipment and
ordinance.
V - Velocity, now used in defining air speeds:
VA = Maneuvering Speed (max structural speed for full control
deflection)
VD = Max Dive Speed (for certification only)
VFE = Max Flaps Extended Speed
VLE = Max Landing Gear Extended Speed
VLO = Max Landing Gear Operation Speed
VNE = Never Exceed Speed
VNO = Max Structural Cruising Speed
VS0 = Stalling Speed Landing Configuration
VS1 = Stalling Speed in a specified Configuration
VX = Best Angle of Climb Speed
VXSE = Best Angle of Climb Speed, one engine out
VY = Best Rate of Climb Speed
VYSE = Best Rate of Climb Speed, one engine out
VARIOMETER - A panel instrument, often as simple as a tiny ball
in a vertical tube, indicating subtle OITCH movements of an
aircraft.
VENTRAL FIN - A fin/rudder extension on the bottom of a
fuselage. Opposite of DORSAL FIN.
VENTURI TUBE - A small, hourglass-shaped metal tube, usually set
laterally on a fuselage in the slipstream to create suction for
gyroscopic panel instruments. Now outdated by more sophisticated
means.
VFR - Visual Flight Rules that govern the procedures for
conducting flight under visual conditions. The term is also used in
the US to indicate weather conditions that are equal to or greater
than minimum VFR requirements. Also used by pilots and controllers
to indicate a type of flight plan.
VFR ON TOP - Flight in which a cloud ceiling exists but modified
VISUAL FLIGHT RULES are in effect if the aircraft travels above the
cloud layer.
VISUAL METEOROLOGICAL CONDITIONS (VMC) - Meteorological
conditions expressed in terms of visibility, distance from clouds,
and ceiling equal to or better than specified minima.
VOR - VHF OmniRange. A ground-based navigation aid transmitting
very high frequency (VHF) navigation signals 360 in azimuth, on
radials oriented from magnetic north. The VOR periodically
identifies itself by Morse Code and may have an additional voice
identification feature. Voice features can be used by ATC or FSS
for transmitting information to pilots.
VORTAC - VOR + TACAN (Tactical Air Navigation); combined radio
navigation aids.
VSI - Vertical Speed Indicator. A panel instrument that gauges
rate of climb or descent in feet-per-minute (fpm). Also Rate Of
Climb Indicator.
WASH-IN, WASH-OUT - A method of increasing lift by increasing
(Wash-In) or decreasing (Wash-Out) the angle of incidence on the
outer part of an airplane wing to counteract the effects of engine
torque.
WET COMPASS SEE COMPASS
WINGLET - A small, stabilizing, rudderlike addition to the tips
of a wing to control or employ air movement.
WING LOADING - The maximum take-off gross weight of an aircraft
divided by its wing area.
YAW - Of the three axes in flight, this specifies the
side-to-side movement of an aircraft on its vertical axis, as in
skewing. Compare PITCH and ROLL.
YOKE - The control wheel of an aircraft, akin to an automobile
steering wheel.