NASA Ames Aviation Systems Division: Main

Copyright ©1996, American Institute of Aeronautics and Astronautics, Inc.

AIAA Meeting Papers on Disc, 1996, pp. 374-384A9635043, AIAA Paper 96-3517

The NASA 747-400 flight simulator - A national resource for aviation safetyresearch

Barry T. SullivanNASA, Ames Research Center, Moffett Field, CA

Paul A. SoukupNSI Technology Services Corp., Sunnyvale, CA

AIAA Flight Simulation Technologies Conference, San Diego, CA, July 29-31, 1996,

Technical Papers (A96-35001 09-01), Reston, VA, American Institute of Aeronautics and

Astronautics, 1996

We describe the NASA-Ames Current Technology Glass Cockpit Flight Training Simulator, located at MoffettField, California. This unique simulator is used to conduct aviation human factors and airspace operationsresearch. The simulator is an exact replica of a cockpit of one of the most sophisticated and advanced aircraftflying in the world today. Although the simulator replicates a typical flight training simulator, it has uniqueresearch capabilities above and beyond the normal training simulator that is used to train today's airline pilots. Wedescribe the NASA simulator and its advanced features, including its unique research capabilities. We alsodescribe some of the research that has been conducted in the cab since its installation, and review some of theupgrades that are currently in progress or will be conducted in the near future. (Author)

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96-3517

A96-35043AIAA-96-3517-CP

THE NASA 747-400 FLIGHT SIMULATOR: A NATIONAL RESOURCE FORAVIATION SAFETY RESEARCH

Barry T. Sullivan, NASA-Ames Research Center *Paul A. Soukup, NSI Technology Services Corp. **

ABSTRACT

This paper describes the NASA Ames Research Center'sCurrent Technology Glass Cockpit Flight TrainingSimulator located at Moffett Field, California. Thisunique simulator is used to conduct aviation humanfactors and airspace operations research. The simulatoris an exact replica of a cockpit of one of the mostsophisticated and advanced airplanes flying in the worldtoday. Although the simulator replicates a typicalflight training simulator, it has unique researchcapabilities above and beyond the normal trainingsimulator that is used to train today's airline pilots.This paper will describe the NASA simulator and it'sadvanced features, including it's unique researchcapabilities. It will also describe some of the researchthat has been conducted in the cab since its installation,and will also review some of the upgrades that arecurrently in progress, or will be conducted in the nottoo distant future.

INTRODUCTION

During recent years commercial airplanes havetransitioned from cockpits equipped with analoginstruments, gauges and switches to highly automatedcomputer driven glass cockpits. Despite numerousadvances in technology, most aviation accidents are stillthe result of human error. In order for scientists tostudy these types of errors a unique facility was neededwhich would enable them to examine the types ofissues that are existent in today's modern cockpits. Inlate 1993, a unique Current Technology Glass CockpitFlight Simulator was installed at the NASA AmesResearch Center's Crew-Vehicle Systems ResearchFacility (CVSRF). This simulator provides researcher'sand scientists with a means to explore issues pertainingto aviation human factors and airspace operations in afull-mission simulation environment. This uniquesimulator is but one integral component of theCVSRF. The CVSRF, located at Moffett Field inCalifornia, is a national research facility which wasbuilt in the early 1980's to study aviation safety issues.

The CVSRF is comprised of two full-mission flightsimulators - an Advanced Concepts Flight Simulator(ACFS) and a Current Technology Glass CockpitFlight Simulator, as well as an air traffic control (ATC)simulator. The ACFS represents a "generic"operational flight deck of the future, while the CurrentTechnology Glass Cockpit Flight Simulator reflects astate of the art aircraft equipped with today's latesttechnological advances. Each of the simulators areintegrated with the facility's ATC simulation providingthe capability to perform complex full-mission humanfactors and airspace operations studies. This paper willfocus strictly on the features and capabilities of theCurrent Technology Glass Cockpit Flight Simulatorand how these features are utilized in supportingnational research programs related to improving aviationsafety.

The NASA Current Technology Glass Cockpit FlightSimulator is an exact replica of a United AirlinesBoeing 747-400 airplane cockpit. It represents amodern commercial transport aircraft incorporatinghighly advanced autoflight and guidance systems,including a sophisticated integrated avionics andwarning system (A picture of the 747-400 simulatorcockpit is shown in Figure 1). All systems within thesimulator function and operate just as they do in theactual airplane, allowing researchers and scientists toconduct studies examining the human-to-human andhuman-to-machine interfaces encountered in the flightdeck environment with a high degree of fidelity andrealism. Unlike the typical flight training simulatorused by the airlines, the NASA 747-400 simulator isenhanced with special research capabilities to supportthe many programs utilizing the cab. Customersoriginate from within NASA, industry, the airlines,universities and other government agencies such as theFederal Aviation Administration (FAA). Researchobjectives include developing fundamental analyticexpressions of the functional performance characteristicsof aircraft flight crews; formulating the principles anddesign criteria for aviation environments of the future;evaluating the integration of new subsystems incontemporary flight and air traffic control scenarios; andthe development of new training and simulationtechnologies that are required by the continued technicalevolution of flight systems and of the operationalenvironment.

* NASA 747-400 Simulator Manager, AIAA Member** 747-400 Simulator Project Engineer

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AMERICAN INSTITUTE OF AERONAUTICS AND ASTRONAUTICS

SIMULATOR DESCRIPTION

The NASA 747-400 Simulator was built by CAEElectronics Ltd. and was installed at the CVSRF inSeptember 1993. The 747-400 simulator is configuredto United Airlines Tail #RT612 and is certified to theFederal Aviation Administration's (FAA) Level Drequirements in accordance with Federal AviationRegulation (FAR) Part 121 Appendix H and AdvisoryCircular AC120-40B, dated 29 July 1991. Thesimulator is also certified to the International CivilAviation Organization's (ICAO) Level II InternationalQualification Standards, as defined in the internationaladvisory circular, International Standards for theQualification of Airplane Flight Simulators, datedJanuary 1, 1992. These levels of certification arerecognized by the FAA and industry as the highestpossible levels of certification for airplane simulators inthe world and provide immense credibility to thenumerous research programs that are conducted in theNASA 747-400 simulator. The simulator compartmentincludes the cockpit flight deck, observer seats, anexperimenter operator control station, and anengineering terminal. A floor mounted access stairwayis provided to allow access to and from the flight deckcompartment. Simulator features include a VITAL Vilevisual system, a digital control loading and motionsystem, a weather radar system simulation, and a trafficalert and collision and avoidance system. Other keyfeatures which will be described include the 747-400cab's advanced aircraft avionics, integrated displaysystem, digital sound/aural cues system, the simulator'shardware and software architecture, and it's uniqueresearch specific capabilities.

VITAL Vile VISUAL SYSTEM

In compliance with FAA Level D requirements, the 747cab is equipped with a Flight Safety InternationalVITAL Vile visual system. The VITAL Vile withphoto texturing and superior scene quality depicts outthe window scenes in either day, night, dawn or duskconditions. The visual system is a 3 channel, 4monitor cathode ray tube (CRT) based system driven bya Motorola Delta series computer providing a 36 degreesvertical by 88 degrees horizontal field of view, usingzero gap optics. The CRT monitors are raster-calligraphic and are capable of producing approximately500,000 pixels and between 600 to 750 texturcdpolygons per channel, as well as 1,000 calligraphiclightpoints for a day scene, and 5,000 lightpoints fornight/dusk/dawn scenes. Numerous customized airportvisual database scenes are simulated including airportscenes for San Francisco, Atlanta, Los Angeles,Boston, Chicago, Denver, Dallas-Fort Worth, NewYork, Honolulu, Hong Kong, Melbourne and Heathrowto name a few. Other customized databases can bedeveloped through the use of an off-line visual modeling

station. The ability to model terrain profiles is alsopossible. In addition, a generic airport scene capabilityis also provided in order to simulate non-customizedairport scenes. Special weather scenes includingweather fronts, thunderstorms, rain, lightning, hail,snow, fog and patchy fog are also available. Control ofvisibility, runway, airport and ambient terrain lighting,as well the presentation of other ground and air traffic isalso available.

Figure 1 - Picture of 747-400 Simulator Cockpit

CONTROL LOADING and MOTION SYSTEM

Also in compliance with Level D requirements, thesimulator includes an advanced digital control loadingand six degree-of-freedom motion system. This systemutilizes hydrostatic actuators powered by a remotelylocated hydraulic power supply to provide accuratemotion and control feel forces. The hydraulic systemconsists of a CAE 600 series motion hydraulic supplyunit consisting of two motor pump units connected inparallel. The hydraulic supply unit, connected to themotion base frame hydraulic system by flexible hoses,feeds the six servoactuator assemblies and the controlloading actuators. The motion base frame hydraulicassembly consists of one pressure line, one return line,two drain lines for upper and lower servojack drains, andthree precharged accumulators so that the systempressure does not fall below safe operational levelsduring worst case conditions. Hydraulic pressurerequired for control loading is supplied by the controlloading pump in the hydraulic power supply unit. Inthe event of a control loading pump failure, the motionpump is also capable of supplying the control loadingsystem with no adverse effect on motion performance.The cabinet housing the digital control electronics alsoserves as an interface to the host computer driving the

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simulator. This stand-alone DN1 cabinet houses thedigital electronics, associated controls, display panels,power supplies, and test features required to control themotion and control loading systems. A CAEcustomized C30 board is the primary computingelement in the DN1 based motion and control loadingsystems. The C30 computes aircraft manufacturercontrol surface models at a rate greater than 500 Hz.Control loading and motion servo loops run at aniteration rate of greater than 2 kHz. The software forthe C30 is downloaded from the simulator hostcomputer at load time. The C30 software communicateswith the host-resident control loading and motionsimulation through a serial ethernet link.

The motion system software provides cockpitmovements in six degrees of freedom with movement inspace of the cockpit of the simulated aircraft. Thecockpit location is calculated as a moment arm from theaircraft's dynamic center of gravity. An adaptive filtersoftware driver program is used to generate motioncommands from linear and angular accelerations fromthe flight equations. The motion system providesphysical sensations felt at the onset of an acceleration,which is then followed by low-level accelerationwashout. Sustained longitudinal and lateral accelerationcues are created by use of the earth's gravity vector, andpitch and roll tilts of the cockpit. Buffet characteristicsoccur during appropriate flight conditions and matchaircraft flight test data within very tight tolerances asdetermined in the FAA Advisory Circular AC120-40B.Special effects include the simulation of bodyaccelerations, flap and gear buffets, stall buffets, highspeed buffets, spoiler buffets, thrust reversers, enginevibrations, ground reaction forces, and weather effectssuch as turbulence, thunderstorms, and windshears.

The CAE 600 series motion system has an actuatorstroke length of 54 inches and is capable of supportinga load of 22,000 Ibs. It can simulate accelerations of+/- 1 g in the vertical direction and +/- 0.7 g's in thelateral and longitudinal axes. The maximum excursionis at least -37.5 deg to +32.5 deg in the pitch axis, +/-32 deg in the roll axis, and +/-37.S deg in the yaw axis.The maximum velocities are at least +/-30 deg/sec inthe pitch axis and +/-32 deg/sec in the roll and yawaxes. The maximum accelerations are at least +/-250deg/sec/sec in all three rotational axes.

The simulator also includes automated testing andtuning features to assure control loading and motionsystem fidelity. In addition, the simulator is man-ratedto ensure that the simulator is safe and that all possibleprecautions have been implemented for all users andparticipating subject pilots using the cab. A series ofinterlocks have been implemented to ensure operationalsafety. In order for the motion system to be activatedeach of the interlocks must be closed. Should any of

the interlocks be opened, the motion system willdeactivate and come to a rest position, thus ensuringoperational safety. Figure 2 depicts the 747 simulatoron motion.

Figure 2 - Picture of 747 simulator on motion.

WEATHER RADAR SYSTEM SIMULATION

The 747 simulator includes a weather radar systemsimulation which is based on using stored weather cellshapes, which are scanned under software control topresent a realistic radar display of a weather front.These fronts must be closely coupled with the 747simulator's visual and motion systems to ensuresimulation fidelity and realism and include precipitationand turbulence effects. Weather radar displayinformation is presented to the pilots via the navigationsystem displays. Each of the weather cells has avertical profile enabling the simulation of antenna tilteffects by displaying the projected image of the cloudhorizontal plane at the intersection of the antennaboresight and the centerline of the weather cell. Specialeffects such as visibility, lightning and thunder can alsobe selected for added realism. Range attenuation andweather cell occultation are also simulated. Sensitivitytime control and path attenuation compensation are alsosimulated with respect to receiver characteristics. Up to20 weather fronts can be built and stored in the NASA747's weather radar system simulation. Each weatherfront can contain up to 20 weather cells, with amaximum of 5 cells along any azimuth. Nonadditivemixing of weather cells is also possible to create newshapes by overlapping existing shapes. The weatherradar system software resides partly in the hostcomputer and partly in the weather radar processorboard. The host resident software performs databasemanagement, radar control monitoring and data

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processing. The board resident software performs theweather cell scanning and the radar beam processing foroccultation, range attenuation and compensation.

TCAS

The 747 simulator includes a Traffic Alert and CollisionAvoidance System (TCAS II) which has beenimplemented according to the Minimal OperationalPerformance Standards (MOPS) RTCA DO-185. ATCAS II processor which provides the necessaryinterface to drive the 747 TCAS displays and thecorresponding aural warnings for traffic and resolutionadvisories is simulated in the simulator's hostcomputer. The host computer simulation softwaregenerates the flight paths for intruders and other traffic,as well as controls and formats all TCAS processorinputs and outputs. The 747's navigation display andprimary flight display are used to depict traffic andresolution information. TCAS intruders can becontrolled by one of two methods on the 747 simulator.The first is by the simulator's own TCAS controlutility which can generate as many as 12 intruders atone time within a 15 mile radius. The second is bysending intruder information via the CVSRF's air trafficcontrol simulator. Typical threats include trafficadvisories, resolution advisories with no climb/nodescend commands, resolution advisories withclimb/descend commands, resolution advisories withfurther crew action required commands, and resolutionadvisories with further crew action required in thepresence of a second threat commands. Transponderequipment for intruder aircraft can be selected by anoperator as either mode A, mode C, mode S, or none.Intruder aircraft with mode A transponders provide onlybearing and range information on the TCAS displays.Mode C and S transponders provide relative altitude,bearing and range information, and nontransponderequipped intruders do not generate any displayinformation. Resolution advisories are provided foronly mode C and mode S transponder equipped aircraft.

AIRCRAFT AVIONICS

The B747-400 simulator's advanced avionics includesseven aircraft Line Replaceable Units (LRUs) - twoFlight Management Computers (FMCs), three Multi-function Control Display Units (MCDUs), an ARINCCommunications, Addressing and Reporting System(ACARS) Management Unit, and a Ground ProximityWarning System (GPWS) Unit. The Honeywell FMCshandle flight performance management, navigation,guidance, thrust control, and display data processing.Through an ARINC interface, the FMCs receiveinformation from other LRUs such as the MCDUs andthe ACARS, and also from simulated systems such asthe Inertial Reference System (IRS), Global NavigationSatellite Sensor Units (GNSSUs), radios, Air Data

Computers (ADC), and fuel system. The data receivedby the FMCs must behave exactly as in the aircraft.Any discontinuity or irregularity will result in theFMCs acting abnormally. However, certain actionsthat do not occur in the aircraft cannot be avoided in thesimulator. For example, maneuvers such asrepositioning the simulation from point to point in asingle iteration or freezing the simulation will causeundesired effects such as winds or inaccurate trajectorycalculations. Software in the FMCs called SIMSOFThandles these situations by using an ARINC 610protocol which will inhibit certain FMC inputs andcomputations. Outputs from the FMCs go to the hostcomputer on the ARINC interface to be used as inputsto the various simulated systems such as the IntegratedDisplay System (IDS), the Central MaintenanceComputer (CMC), and the autoflight system. TheFMCs also send outputs to the MCDUs, the ACARS,and the cockpit printer. The FMCs are loaded withoperational software and a navigational database. Theoperational software also contains a performancedatabase in order to provide the FMCs with data it needsto calculate pitch and thrust commands. Thenavigational database includes information that wouldbe contained on navigational charts such as location ofnavigational aids, airports, runways and other selectedairline information. New operational software can beloaded when required, and a new navigation database isnormally updated every 28 days.

The three MCDUs, which are also built by Honeywell,allow the pilots to interact with the FMCs through akeypad and display. The majority of system messagesand warnings are displayed through the IDS. However,the FMCs can generate forty-two different messages tobe displayed in the scratch pad of the MCDUs. Thesemessages are related to guidance and navigational itemsthat require action by the flight crew. The two forwardMCDUs permit the Captain and First Officer tointerface with and monitor the FMCs, the navigationradios, the ACARS, and SATCOM. The center, rearMCDU only interacts with the ACARS, SATCOM,and CMC. SATCOM is a voice and data satellite basedcommunications system that represents a significantimprovement over HF radio for connectivity, voicequality, and traffic volume capacity, especially in theoceanic environment. The CMC software simulation islimited to warning system confidence tests and selectionof various aircraft system maintenance pages.

The Collins built ACARS unit serves as a method ofcommunication between a ground station and the B747-400 aircraft using VHP radio or SATCOM. TheACARS interfaces directly with the FMCs, theMCDUs, the VHF/SATCOM receiver, and the cockpitprinter. ACARS has a voice and data mode,respectively. In the voice mode, conventional audiotechniques are employed. While in the data mode, the

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flight crew transmits and receives data from a groundstation via a digital data-link. The flight crew can send(downlink) position reports, fault reports formaintenance, and requests for information to the airlinedispatcher. Information such as departure details,dispatch release, or free text can be sent (uplink) to theflight crew. In the simulator, information is data-linkedvia a dedicated interface card to the experimenter operatorstation (EOS). The simulated ground station on theEOS has the capability of receiving downlinks andgenerating uplinks.

The Sundstrom GPWS unit provides ground proximitywarnings with appropriate voice, and other aural andvisual indications.

DIGITAL SOUND/AURAL CUES SYSTEM

An 8-channel sound system with 19 speakersimplemented throughout the entire flight compartmentsimulates the various sounds and aural warnings that areaudible within the 747 flight simulator. Simulatedsounds are generated, processed and controlled digitallyusing digital signal processing techniques. Attention todirection, frequency and amplitude of simulated soundsensures realism. Controls have been provided foroverall sound system volume, as well as softwarecontrol to adjust the relative levels of simulated sounds.Simulated sounds are automatic and are representative oftypical sounds heard throughout all phases of flight.These include aerodynamic hiss, engine surge, reversersounds, compressor stall, runway rumble, explosivedecompression, crash, rain, hail and thunder. The soundsystem produces the appropriate noises through a seriesof frequency generators, noise generators, and soundlook-up tables. The sounds are derived from audio tapessupplied by the aircraft manufacturer. Data obtainedfrom the spectral analysis of these recordings is enteredinto the host computer using various utilities. A serialethernet and a Datapath C Microprocessor ControllerDMC-16 card links the host computer to the soundcards in the sound chassis. Pure sounds are generated ona dedicated circuit card and sent to the appropriateloudspeakers via mixers and amplifiers. Other cards arededicated to producing noise such as white noise andimpact sounds. Using host based sound frequencyanalysis tools, sound measurements can be taken andverified against flight test results ensuring fidelity andrealism. This is a requirement for FAA Level Dcertification.

The audio interface is composed of an audio chassis anda Digital Audio System Interface Unit (DASIU). In theaudio chassis, signal generator cards produce varioustones for communications and avionics including auralalerts generated as part of the Modular Avionics andWarning Electronics Assembly (MAWEA) system.These include bells indicating an engine or APU fire,

unsafe warning sounds, caution sounds, selectivecalling, ground proximity warnings, altitude alerts, andstall warning alerts. A personal computer based digitalvoice system simulates the ATIS and VOICE.

SIMULATOR HARDWARE ARCHITECTURE

The simulator is composed of computers that simulateon board systems and stimulated computers that existon the B747-400 aircraft. Taking advantage of IBM'slatest technology over the last few years, the hostcomputer driving the majority of the simulation, is asingle processor IBM RISC 6000, Model 580. Thehost is networked to various computers including aseparate data collection computer which is an IBMRISC 6000, Model 560, and four Silicon Graphics Inc.(SGI) Indigos which control the graphics for the twoexperimenter operator stations. Using a non-standardethernet protocol for real-time and higher bandwidth, thehost is connected to an interface that drives thesimulator hardware. The simulation system interfaceincludes a CAE standard input/output (I/O) interface, aspecial ARINC interface, a High Resolution GraphicsCard (HRGC) interface, a control loading and motionsystem interface, a visual system computer interface,and an audio and sound system interface.

The CAE standard I/O interface handles analog signalsfor such systems as the flight instruments and discretesignals such as push buttons and circuit breakers. TheARINC-429 interface is a serial data bus that connectsthe host computer to the busses of stimulated aircraftcomponents that utilize the ARINC-429 standard. TheARINC-429 protocol specifies a serial system for datainterchange between different aircraft LRUs. Thehardware portion of this interface is based on three typesof boards that exchange and format data between thehost computer via the ethernet and the ARINC DMCcard.

The HRGC interface between the host computer IDSsimulation and the six high resolution CRT displays inthe cockpit consists of three chassis containing elevenHigh Resolution Graphics Cards and five DMC-16boards. The HRGC is a microprocessor based card thathas computing power comparable with an SGI IRISworkstation. It displays 1280x1024 pixels at a refreshrate of 60Hz. It is capable of simultaneous display of256 colors and draw rates of 117,000 vectors per secondand 44,000 filled triangles per second. The DMC-16boards provides control and communications betweenthe HRGCs and the host computer system. EightHRGCs are used to drive the IDS pages and three areused for weather radar system applications. TheHRGCs contain all the graphics information needed todrive the CRTs. A videoswitcher carries the red, greenand blue (RGB) signals from one set of HRGCs to agiven CRT. A block diagram depicting the 747

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VisualComputer

HostComputer

EOS Computers

DataCollectionComputer

TAL

BM

-580

To ATC Simulator

EOS Computers

Interface

sS

B747 Simulator

Figure 3 - NASA 747-400 Simulator Hardware Architecture

simulator's hardware architecture is shown in Figure 3.

SIMULATOR SOFTWARE ARCHITECTURE

All software on the IBM 6000s and SGI Indigos operatein a UNIX environment. The simulation softwareprograms are written in high level languages such asFORTRAN or C, and are structured in a modularfashion. Configuration and control of the software isperformed by a CAE developed real-time executivecalled SIMEX-Plus. It controls the linking, loading,executing, and scheduling of software modules. Forconfiguration control the utility uses the load moduleconcept. Each load module is a complete andindependent package of the simulation called aconfiguration. Therefore, a configuration can bedeveloped and maintained for an experiment withoutimpacting other experiments. SIMEX-Plus alsoensures that software resident on the simulator isproperly controlled and that a history of changes is kept.Other utilities include a computerized test system whichenables users to monitor, set, or plot global variables.The performance evaluation utility monitors the timingof all modules and processes so that users can be surethat no excessive computation is occurring. Also, anavigational database development tool allows users tocreate or modify navigational features such as radio aidsor runways. There are also utilities for softwaremaintenance and simulator status reporting.

All critical simulation models such as flight controls,aerodynamics, motion, flight instruments, aircraftposition, and visuals execute at the critical rate of 30Hz. The scheduling is dictated by two dispatcherprograms, one for synchronous operations and the otherfor asynchronous operations. Modules are called atdefined intervals anywhere from 33 to 266 millisecondson the synchronous dispatcher, and from 50 to 300milliseconds on the asynchronous dispatcher. Amodule's position in the dispatcher depends on thenature and significance of it's computations. Preciseand balanced scheduling on the IBM RISC 6000-580ensures that the facility enjoys a fifty percent spare timecapability that can be used for development and otherexternal purposes.

RESEARCH SPECIFIC CAPABILITIES

The NASA B747-400 simulator is unique in that itspurpose is to support human factors and airspaceoperations research rather than being dedicated to flightcrew training. This requires differences primarily inthree areas - the ability to modify the flight displays andother flight crew interfaces, enhanced control overexternal effects, and the capability for powerful butflexible data collection and performance measurement.

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PROGRAMMABLE FLIGHT DISPLAYS

The 747-400 is equipped with an Integrated DisplaySystem (IDS) which is composed of the ElectronicFlight Instrument System (EFIS) and the EngineIndication and Crew Alerting System (EICAS). TheEFIS portion of the IDS is composed of the PrimaryFlight Display (PFD) and the Navigation Display (ND)for both the Captain and First Officer. The PFDdisplays attitude/direction/altitude/airspeed information,while navigation, performance, and weather radarinformation is displayed on the ND. The EICASdisplays engine data, caution and warning messages, andsubsystem data and faults. On the B747-400 simulator,the IDS is programmable to support the development ofnew or revised flight displays and/or system synopticsto support aviation safety research. The actual aircraftIDS is normally comprised of six integrated displayunits (IDUs), which are driven by three EFIS/EICASInterface Units (EIUs). The information displayed onthe IDUs is controlled by the unique IDU location,control panel command, and automatic or manual sourceswitching. On the simulator, the IDUs are simulatedthrough the use of six commercial, raster-based CRTdisplays which are driven by the HRGC chassis. Whenthe simulator is loaded, the HRGCs contain down loadfiles which include all the EFIS and EICAS displayinformation. The down load files can be modified inorder to create or alter IDS display pages. The files canbe edited using a CAE developed utility called TIGERSon a remote graphics workstation. The TIGERS utilityis a windows based tool that allows the user to create ormodify dynamic objects with attached attributes such ascolor, scale, or position that can be driven from the hostcomputer. The IDS simulation model, resident on thehost computer, provides the EFIS and EICAS systemlogic to drive, in real-time, the HRGC graphicssoftware on the IDS pages. The software also providesfor EIU functions, including data processing andformatting for EICAS message generation, andinterfacing with other simulator hardware and softwaresystems. Using the videoswitcher, there is nolimitation as to which IDS page can be displayed onwhich IDU, giving the user even greater flexibility.The IDS simulation facilitates system modifications onan experimental basis without being dependent onaircraft hardware. The NASA 747 simulator was thefirst U.S. simulator with programmable flight displaysto receive FAA Level D certification.

EXPERIMENTER OPERATOR SYSTEM

The Experimenter Operator System on the NASAB747-400 simulator, not unlike training simulators,provides the capability to initiate, monitor, and controlactivities in the cockpit during a simulator session.However, the NASA 747 flight simulator has additionalfeatures such as an off-board experimenter operator

station (EOS), repeater monitors, data collectionfacilities, and the ability to connect with the CVSRFATC simulator and other simulators outside the facility.Each EOS is composed of two touch-screen SGI IRISdisplay systems providing both display of currentinformation and user friendly, touch screen controls formanipulating the simulator. In addition, both the on-board and off-board stations provide control of thesimulator through programmable control panels (PCP's)and various buttons and switches. Each EOS enablesthe operator to manipulate or control a variety ofvariables via different pages and windows, (i.e. theposition set page establishes the simulator on therunway or gate, or trimmed in flight at any airport inthe world that can support a B747-400 aircraft). Weatheris altered on the weather set page where winds,temperatures, turbulence, and special effects such aslightning, thunder, or blowing snow can be set.Aircraft weight and balance are controlled on the aircraftconfiguration page. Approximately three-hundredsystem malfunctions are accessible through individualmalfunction control pages. However, the primarymeans by which an operator can control an experimentand the flight tasks in a repeatable manner are throughscenarios developed off-line in advance of theexperiment, using a PC-based Scenario Editor Utility(SEDU). Scenarios provide the researchers with theability to automate and control configurations andevents during a simulation by preprogramming a seriesof EOS functions. Another important tool available onthe EOS is the capability of creating a "snapshot" of thesimulator that can be recalled at a later time. Snapshotscan be permanently saved as "setups" and then usedwithin a scenario. This feature is important in theresearch environment so that a researcher can repeat aprocedure from a precise initial starting point in order toattain reproducible results. An additional benefit to theresearchers are the off-board EOS station repeatermonitors which display all six cockpit displays and anout-of the-cockpit scene to allow the researchers toobserve, in real-time, exactly what the pilots are seeinginside the cab.

EXPERIMENT DATA COLLECTION

The B747-400 simulator is equipped with a specializedsystem for collecting run data during a simulatorsession. A list of variables and the rate at which theywill be captured is created on the IBM RISC 6000-560data collection computer before the session. The nameof the list is then entered on the EOS to initiate therecording of the data. The information is recorded bythe data collection computer and is stored on hard drives.An average of 2000 parameters (4 bytes) at 30 Hz canbe recorded on contiguous disk space of up to 11.3gigabytes. Experimental data can also be collected inthe form of audio and video. The EOS can control theon/off state and vary the volume of up to eight different

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microphones in the cockpit or at the EOS stations. Theaudio channels are then mixed together via adigital/audio mixer to provide an analog output to theoff-board speakers and the video recorder. In addition,six miniature, low light video cameras arc installedaround the cockpit giving the researcher the ability tovideotape six specific views plus an out-of-the-cockpitview during the simulator session. Time-stampedvideo/audio recording combined with digital datacollection gives the researcher a powerful tool to studythe crew and crew-to-vehicle interactions during asimulator session or experiment.

AIR TRAFFIC CONTROL (ATC) SIMULATIONINTERFACE

The CVSRF has a separate air traffic control (ATC)simulator which provides realistic air-groundcommunications and coordinates the appearance ofaircraft visible from the simulator cockpit. This systemis hosted on a separate computer, a VAX-6310. TheATC simulation consists of four air traffic controllerstations and four "pseudo-pilot" stations. Each one ofthese stations is equipped with multi-channel voicedisguisers and are linked to each other, as well as to the747 simulator. The four "pseudo pilot" stations areable to control numerous pseudo-aircraft at one time.The ATC simulator interacts with the communications,TCAS, and visual systems on the B747-400 hostcomputer. The EOS provides a control switch whichdetermines whether the pseudo aircraft are displayed asTCAS intruders on the B747-400 or whether theintruders originate from the host computer'spreprogrammed TCAS scenarios. This gives researchersthe option to monitor and record the interaction betweenthe flight crew and ATC, or the flight crew withresearcher-designed TCAS scenarios. The ATCsimulator is connected to the host computer via the datacollection computer through a direct memory access(DMA) link. This link consists of a DR11W interfaceresiding on the data collection computer and a DRB32Winterface on the ATC simulator's VAX 6310.

LINKS TO OTHER SIMULATION FACILITIES

The B747-400 simulator is currently linked with twoother facilities: the FA A Technical Center in AtlanticCity, and the FAA Aeronautical Center in OklahomaCity. The FAA Technical Center includes a unique airtraffic control simulation complex which is used toconduct airspace operations research. The facility islinked to several other simulators throughout thecountry via a high speed digital voice/datacommunications system. The 747 is linked to theTechnical Center by two discrete voice and data linesrespectively, which operate at 9600 bps each. Thesefour lines are fed through a multiplexor that combinesall of the voice and data communications into a single

56 Kbps dedicated line. The 747 is one of severalparticipating simulator's around the country, each ofwhose lines are combined into a single 1.544 Mbps T-lline at the FAA Technical Center. The voice linestransmit all of the flight crew-controllercommunications. The data lines transmit flightsimulator state information such as airspeed, positionand altitude to the Technical Center and ATCinformation such as the time and aircraft designation tothe flight simulator.

An additional link to the FAA's Aeronautical Center inOklahoma City allows FAA personnel to monitor real-time results of an on-going experiment. This linkemploys a simple modem protocol over the telephonelines. Flight simulator state information such asposition, airspeed, altitude, spatial deviations, and autopilot modes are sent at 9600 bps.

RESEARCH PROGRAMS

Although the NASA 747-400 flight simulator ismaintained to the highest recognized certificationstandards for training simulators, it is not used fortraining. It is used strictly for aviation human factorsand airspace operations research. Participating subjectcrews are line-qualified 747-400 pilots, thus furthervalidating the value of the results of the researchprograms conducted in the simulator. Since thesimulator's activation in the fall of 1993, over twentystudies have been conducted in the NASA 747simulator. Typical studies include the following:

Data-Link: A series of studies have been conducted byNASA and FAA to examine the use of digitizedinformation transfer for the presentation of air trafficcontrol information. These studies are concerned withtrying to reduce the number of incidents due tocommunications problems between pilots and air trafficcontrollers. The results of these studies will help in thefuture design and development of guidelines andprocedures for the implementation of digital informationtransfer in future commercial transport aircraft.

Converging Approaches: The FAA's System CapacityOffice developed a program to focus on the improvedutilization of instrument landing system (ILS)converging approaches and examined the relatedoperational aspects towards improving efficiency.Currently, ILS terminal procedures (TERPS) missedapproach primary obstacle clearance surface criteriaimpose capacity constraints on ILS convergingapproach operations. The FAA investigated proceduresutilizing flight management system equipped aircraft toconduct simultaneous converging missed approachesfrom decision heights between 500 to 700 feet aboveground level. Results from these studies showed that

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converging approaches were possible and could beperformed safely using lateral offsets from the localizerbetween 90 to 100 degrees, thereby allowing decisionheight minimums to be reduced. Implementation ofthese new procedures are currently in process forChicago O'Hare and Dallas-Fort Worth Airports using areduced decision height of 650 feet.

Center TRACON Automation System DescentAdvisories: This experiment examined thecompatibility of a new air traffic control CenterTRACON Automation System (CTAS) descentadvisory clearance with the operational proceduresavailable on current commercial aircraft. The intent ofthis study was to identify and eliminate any problemswith the delivery, timing or execution of successfullyflying CTAS descent advisories. CTAS is a new airtraffic controller automation tool which helpscontrollers schedule traffic more efficiently. Results ofthis study will help develop new phraseology andguidelines for using CTAS descent advisories whichwill eventually be tested during field tests at DenverInternational Airport.

Moving Map Display: This NASA study evaluated theuse of an integrated moving map display for presentingground taxi information which enabled pilots tonavigate about the terminal area in low visibilityweather conditions. Navigation data to the map displaywas provided via a simulated differential globalpositioning system (DGPS). The information waspresented to participating flights crews on theirnavigation displays via data-link. The enhanced mapdisplay depicted a topographical view of the terminalarea including runways, taxiways, gates, position ofother aircraft, ATC clearance information, relativeaircraft position, heading and ground speed. Results ofthis study indicated a definite reduction in crew workloadin using the integrated map display versus the use of theconventional paper Jeppesen maps that are typicallyused today. In addition, crew's taxi time performancewas improved as well by using the enhanced mapdisplay. Other potential benefits possibly gained bythis type of display include improved terminal areacapacity by enabling airplanes equipped with thisadvanced technology to operate in reduced visibilityconditions, and a possible increase in safety by reducingthe chances of possible ground incursions.

Multiple Parallel Approaches Program: This on-goingFAA program evaluated the traffic handling capabilitiesof conducting multiple simultaneous independentinstrument landing system approaches in instrumentmeteorological conditions. These studies evaluated thefeasibility of conducting dual and triple parallel runwayoperations with varying runway separation distances bytaking advantage of advanced radar systems such as thePrecision Runway Monitor (PRM). This advanced radar

system employs a faster radar sweep, allowing moreaccurate tracking of terminal area traffic. The 747-400simulator was one of several simulators connected tothe FAA Technical Center's air traffic controlsimulation complex via a high speed digital voice/datacommunications system. The results of this studyprovided the FAA with a new separation standard forparallel approach operations.

3-D Audio: This NASA study evaluated the use ofspatialized sound techniques for detecting other groundtraffic during taxi operations in the terminal area. Forthis study, directionalized auditory warnings were brieflyenunciated over customized (stereo) pilot headsets toattempt increasing the crew's situational awarenessabout non-visible hazards such as other nearby aircraft,or as annunciations for intersecting taxiways during taxioperations. The main thrusts of this study were todetermine the time to complete taxi routes underspatially-audio assisted and non-assisted conditions,incursion warnings and taxiway announcements.Preliminary results indicated that all participating pilotsexpressed a strong preference for the ground collisionavoidance alert to be included with a future system,hopefully decreasing the amount of time a pilot wouldneed to respond to a possible ground incursion.

Propulsion Controlled Aircraft: This study evaluated theuse of a propulsion only flight control system in theevent in which an airplane's primary flight controlsystem malfunctioned or became inoperative. Thisstudy made use of control laws developed at NASADryden to control aircraft flightpath angle bymanipulating aircraft thrust to maintain pitch and rollcontrol during approach and landing operations. Resultsof this study indicated that participating pilots were veryexcited about the fly-by-throttle concept. A follow-onstudy is currently being planned that will extend the useof the propulsion controlled flight algorithms to includeengine out performance as well as other phases of flightfor a four engine aircraft.

These programs are just a representative sample of thetype of programs that are supported on the NASA 747-400 simulator. Over the upcoming years, the 747simulator will be used extensively in support ofNASA's Terminal Area Productivity (TAP) andAdvanced Air Traffic Technologies (AATT) Programs.In addition, NASA will continue to work with the FAAin trying to resolve human factors and airspaceoperations issues by supporting the FAA's NationalPlan for Human Factors and Free Flight Programs.

FUTURE PLANS

Although the NASA 747-400 simulator represents astate of the art aircraft, it too will evolve over the

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upcoming years. Probably the most significant upgradeto the simulator which is currently taking place in theairplane as well, is the implementation of the FutureAir Navigation System (FANS). FANS is an advancedavionics system upgrade that will utilize global satellitebased information for communications, navigation,surveillance and air traffic management for the twenty-first century. The FANS upgrade is primarily a Boeing-Honey well implementation to upgrade the 747-400 withFANS compliant avionics, taking advantage of satellitenavigation and communications systems, andtechnology advances in automation. FANS will utilizeGlobal Positioning System (GPS) information foraircraft tracking and navigation, supporting enroute andterminal area non-precision approaches. In the future,ground based augmentation is expected to extend theGPS capabilities by including precision approaches.Other FANS modifications to the simulator includeupgrades to the various installed avionics, specificallythe two FMC's, the three MCDU's, the Multi-inputCockpit Printer, the ACARS Management Unit andSATCOM. Also, there are changes integrated as part ofthe FANS package which require modifications to theappropriate simulated systems including the 747-400'sEICAS, MAWEA system for pending data-linkmessages, and the modification of the navigationdisplays depicting the use of GPS data for primarynavigation. New key features resulting from the FANSupgrade include Automatic Dependent Surveillance(ADS) allowing more precise aircraft tracking, AirlineOperational Communications Data-Link (AOC DL) offlight plan information, winds forecast data and routemodifications, and Air Traffic Control Data-Link (ATCDL) of air-ground messages including clearance uplinks.In the real world environment the ADS and ATC DLfunctions are generally hosted on controllerworkstations with graphical user interfaces for selectingor displaying the data-link information for the airplanesflying in the airspace in the controller's jurisdiction.For the simulated environment, the interaction forground support functions such as AOC DL, ATC DL orADS are provided via specially designed control pageson the 747-400 simulator's Experimenter Operator'sStation (EOS). All data-link applications have airborneand ground-based counterparts which exchange datathrough specially formatted messages and aretransmitted via an ACARS network. The airborne sideof these applications are included as part of the upgradedavionics. The ground based applications requireddevelopment for a simulated environment. Some ofthese features include Required Time of Arrival (RTA)utilizing time based navigation, and RequiredNavigation Performance (RNP) which compares actualposition versus required position on a given route. Thesignificance of the FANS upgrade is that it will enablethe CVSRF to support important national programssuch as NASA's AATT Program and the FAA'sDynamic Aircraft Route Planning (DARP) Program.

These two programs will rely very heavily on the newcapabilities provided by the FANS upgrade.

Other upgrades envisioned over the upcoming yearsinclude the integration of some advanced displaysymbology depicting potential conflict alertingschemes, enhanced collision and avoidance logic,reduced separation, vertical situation, and advancedground taxi displays to name a few. These advanceddisplays will take advantage of the 747 simulator'sreprogrammable flight display capabilities, and willattempt to increase aviation safety by hopefullyreducing pilot workload. In addition, integration of aheads up display is being considered for the 747-400simulator. Technology advances in the future willenable the integration of a smaller and less obtrusiveHUD system which can be used to study advanced HUDsymbologies that will allow pilots to navigate aboutthe terminal in low or zero visibility conditions. As anextension of the FANS upgrade, integration of ADS-Bis envisioned to be installed in all aircraft some time inthe not so distant future. This will allow aircraft todetermine the detection and flight path of other aircraftin the nearby vicinity representing an enhanced trafficand collision avoidance capability.

SUMMARY

The NASA 747-400 Flight Simulator is an essentialand vital tool for studying issues pertaining to aviationhuman factors and airspace operations research. Sinceits inception, numerous studies have been conductedaimed at improving aviation safety and the overallefficiency of the national airspace system. This uniquefacility has enabled and will continue to enablescientists to develop and test new concepts in a realisticcockpit environment through the use of full-missionsimulation. The NASA 747 simulator will allowresearchers to conduct studies that examine how crewmembers interact with each other and how they interfacewith advanced automation concepts in the ever changingflight deck environment. The facility will continue tomake an impact on the current and future aviationenvironment by it's continuous support of importantnational programs such as NASA's TAP Program,AATT Program, the FAA's National Plan for HumanFactors and Free Flight. This facility will continue toplay a vital role in enhancing aviation safety over theyears to come.

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REFERENCES

1. CAE Boeing 747-400 Full Flight Simulator forNASA, Volume 1: Technical Specification, TPD08593-1 Rev. 3, CAE Electronics Ltd., St.Laurent, Canada, June 1992.

2. Shiner, R., Sullivan, B., Man-Vehicle SystemsResearch Facility: Design and OperatingCharacteristics. AIAA/AHS Flight SimulationTechnologies Conference, Hilton Head Island,South Carolina, August 1992.

3. CAE Boeing 747-400 Full Flight Simulator,Software Documentation, Software Avionics,Integrated System Display, 10015347 Rev. 0, CAEElectronics Ltd. St. Laurent, Canada, January 1994.

4. CAE Boeing 747-400 Full Flight Simulator, AudioSystem Maintenance Manual, TPD 10483 Rev. 0,CAE Electronics Ltd., St. Laurent, Canada, January1994

5. CAE Boeing 747-400 Full Flight Simulator, SerialCommunication System Maintenance Manual,TPD 10485 Rev. 0, CAE Electronics Ltd. St.Laurent, Canada, March 1994.

6. CAE Boeing 747-400 Full Flight Simulator,Sound System Maintenance Manual, TPD 10488Rev. 0, CAE Electronics Ltd., St. Laurent, Canada,October 1993.

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