aries: nasa langley's airborne research facility michael s

ARIES: NASA Langley's Airborne Research Facility

Michael S. Wusk

NASA Langley Research Center

Hampton, Virginia

Abstract

In 1994, the NASA Langley Research Center (LaRC)acquired a B-757-200 aircraft to replace the aging B-737 Transport Systems Research Vehicle (TSRV).The TSRV was a modified B-737-100, which servedas a trailblazer in the development of glass cockpittechnologies and other innovative aeronauticalconcepts. The mission for the B-757 is to continuethe three-decade tradition of civil transporttechnology research begun by the TSRV. Since itsarrival at Langley, this standard 757 aircraft hasundergone extensive modifications to transform itinto an aeronautical research "flying laboratory".With this transformation, the aircraft, which has beendesignated Airborne Research IntegratedExperiments System (ARIES), has become a uniquenational asset which will continue to benefit the U.S.

aviation industry and commercial airline customersfor many generations to come. This paper willdiscuss the evolution of the modifications, detail thecurrent capabilities of the research systems, andprovide an overview of the research contributionsalready achieved.

Figure 1: NASA's Boeing 757-200 aircraft is'equipped to conduct a range of research flight tests.

Introduction

A Boeing 757-200 aircraft acquired by NASA in1994 is now serving as a "flying laboratory" foraeronautical research. The aircraft has been

extensively modified to support a broad range offlight research programs to benefit the U.S. aviationindustry and commercial airline customers. Called

ARIES, or Airborne Research IntegratedExperiments System, the aircraft is being used to

conduct research to increase aircraft safety, operatingefficiency and compatibility with future air trafficcontrol systems. It is a vital research tool in supportof the agency's Airframe Systems, Aviation Safety,and Aviation Systems Capacity programs.

The 757 is continuing work begun by the NASA 737-100 in state-of-the-art technologies such as electroniccockpit displays, flight management systems andflight safety devices. Langley's 737 was the first 737off Boeing's production line in 1967 and was inservice with NASA until it was decommissioned in

1997. Existing and projected research needs greatlyexceeded the capabilities of the 737. The 757 offereda more modern airplane that utilized electronicsystems to a much greater extent, and more closelyrepresented the current and projected commercialfleet. During the coming decades, the 757 will bettersupport research and development of the aeronauticalsub-systems for the airlines and the airframe andsystems manufacturers. The airplane has already beenused for several research programs, including:

• Flight-tests to characterize the internalelectromagnetic environment (EME) andvalidate the computational assessment of

electromagnetic effects in commercialtransport aircraft. 4

• The study of jet-engine contrails todetermine their effects on the atmosphere 5.

• Flight-tests using Global Positioning System(GPS) satellite data to perform automatedlandings of the airplane. 6

• Testing of a system to improve the safetyand efficiency of aircraft during landing,taxiing and takeoff by giving pilots acomputerized map showing airport groundoperations. 7

• The study of Winter Runway Operations andaircraft braking performance oncontaminated runways. 8

• Testing of an airborne system that allowsclosely spaced approaches to landingsduring reduced visibility to increase airportcapacity. 9

1American Institute of Aeronautics and Astronautics

• Evaluationof systemsthatwouldprovidepilotswith betterstrategicandtacticalweatherinformationwhileinflight.]o

• Flight evaluations of integrated syntheticvision systems. ]]

Future research will continue to focus on

technologies to improve air safety, efficiency andperformance.

Historv

NASA Langley Research Center operated a B-737-100 for over twenty-five years as a "flyinglaboratory ''1. The aircraft was the prototype 737

produced by Boeing in 1967. After Boeing completedthe certification testing with the aircraft, it wasreconfigured with a research system, including anoperational aft research flight deck, and delivered toLangley. The aft flight deck allowed for safe andefficient testing of advanced cockpit displays andintegration of emerging navigation, communication,and flight guidance and control technologies. Overthe next several decades it completed severalthousand hours of research flight time, testing outmany of the concepts and technologies that exist intoday's modem civil transport aircraft. During the737's service at Langley, vital experience was gainedin the integration, modification, and operation of thishighly complex research facility. This would becomean important factor in the development of areplacement aircraft.

The candidate aircraft was the second 757 built and

the first one produced that was sold to an airline. It ispowered by two Rolls Royce RB211-535E4 turbofanjet engines with each engine generating 40,100 lbs. ofthrust. The maximum take-off weight is 251,000 lbs.The aircraft's max cruise is .86 Mach and it has a

service ceiling of 42,000 ft.

Figure 3:B-757 dimensions

Boeing used this number two aircraft during the FAAcertification testing. The FAA certified the 757 classof jet airliners on December 21, 1982, after 1,380hours of flight-testing over a 10-month period. Firstdelivery of a 757-200 took place December 22, 1982,to launch customer, Eastern Airlines. Eastern placedthe aircraft into service January 1, 1983. Thisdigitally equipped transport, designated N501EA,was flown by the airline until it's bankruptcy in 1991.The aircraft was mothballed at McCarran

International Airport in Las Vegas, Nevada untilNASA finally obtained it from the Eastern Airlinebankruptcy estate. Langley took possession of the$24-million aircraft March 23, 1994. 2

Figure 2: NASA's First Flying Laboratory, theBoeing 737

In the early 1990's it became evident that theemerging research demands and evolvingprogrammatic focuses were starting to overtake theaging B-737. A search was begun for a replacementaircraft that would meet these growing demands andprovide an able research platform to carry forwardthe research effort well into the new millennium. Thesoon-to-be NASA B-757 was located after an

exhaustive analysis of the projected needs and anextensive survey of the jet airliner market.

Figure 4: NASA 557 after the purchaseJ?om Eastern,beJbre changing to the NASA color scheme.

After undergoing a thorough inspection andcompletion of scheduled heavy maintenance checksthe aircraft was delivered to Langley on May 19,1994. Initial familiarization flights were conductedand some minor modifications were begun which


wouldallowthecompletionoftheElectromagneticEnvironmentexperiment.4Followingthecompletionoftheseinauguralflighttests,themomentoustaskofreconfiguringthe aircraft into its researchconfigurationwasbegunin earnest.WhereastheB-737 cameto Langleyalreadyconfiguredas afunctioningtestfacility,manyfactorsdictatedthatthe B-757wouldundergoits metamorphosisatLangley,completedby Langleycivil servantandcontractorstaff.Theexperiencegainedovertheyearsof operationswiththeB-737provideda wealthofcorporateknowledgeand an extremelycapableworkforcetocarryoutthetask.Regardlessoftheseinvaluableresources,thetaskathandwouldbeamonumentalonerequiringtheeffortsofmanypeopleand organizations,includingextensivetechnicalinputsfromBoeingandmanyof theirsubsystemsuppliers.Overthe next severalyears,throughmultiplephases,theaircraftcontinueditsevolutionintoafunctioningflighttestfacility.

It wasduringthistime,inDecember1998,thattheaircraftwasofficiallygiventhe nameARIES,helpingto furtheridentifyits uniquerole as acontributingentityinthefieldofaviationresearch.

Sim-to-Flight Concept

Even before its arrival at Langley, ARIES had beenenvisioned as an integral part of the TransportResearch Facilities (TRF). The TRF is a set of toolsused in a simulation-to-flight concept. This conceptincorporates common software, hardware, andprocesses for both ground-based flight simulators andthe B-757, providing Government and industry withan efficient way to develop and test new technologyconcepts to enhance the capacity, safety, andoperational needs of the ever-changing nationalairspace system 3. These facilities enable a smoothcontinuous flow of the research from simulation to

actual flight test.

Three major facilities are used in the simulation-to-flight concept. The first is the Cockpit MotionFaility (CMF), a multiple -cab, fixed- and motion-based flight simulation laboratory that contains theIntegration Flight Deck (IFD) simulator cab, theResearch Flight Deck (RFD) simulator cab, and theResearch System Integration Laboratory (RSIL). TheIFD cab closely resembles the 757 forward flightdeck or cockpit and is used in support of flight-testing on the ARIES and for aircraft systemsintegration studies. The RFD cab is an advancedsubsonic transport flight deck used for full-crew-workload and full-aircraft-systems integration

development and tests by the research community.The RSIL is a ground-based laboratory version of theARIES on-board research system (described below)and is used for the integration of key hardware andsoftware systems required for simulation. The secondmajor facility is the Flight System IntegrationLaboratory (FSIL), a flight-testing counterpart to theRSIL. The FSIL is used for the aircraft integrationand preflight validation of key hardware and softwaresystems destined for ARIES. The third facility is the757. ARIES currently features an on-board researchsystem called Transport Research System (TRS) andthe Flight Deck Research Station (FDRS), both ofwhich are described later in detail.

ARIES Concept Overview

One of the attributes that made the B-737 such a

powerful research tool was the research or Aft FlightDeck (AFD) located in the cabin area of the aircraft.This allowed a great majority of the research work tobe accomplished in the AFD while still maintaining asterile two-crew safety cockpit up front, in theForward Flight Deck (FFD). In retiring the B-737,Langley's plan for the B-757 has always included the

integration and installation of an AFD onto theaircraft. Resource and budgetary constraints havedictated that a delayed phased approach be used toachieve this full-up research system implementation.

Initial modifications to the B-757 cabin and cockpithave been focused at the establishment of the basic

experimental infrastructure, called the TransportResearch System. The TRS is comprised of theresearch computers and data collection systems usedto support the experiments and tests. This hardware isdistributed throughout the cabin, cockpit, and cargohold areas of the aircraft at both manned and

unmanned pallet stations. Major modificationscompleted in support of the TRS included installationof cooling ducts and distribution of ship's power toeach pallet location, and the installation of overheadcable trays in the cabin to accommodate data signalwiring. Pallet configurations and cabin layouts havechanged as the aircraft modifications have progressedto meet the intermediate research needs, but evenwith the achievement of the current Coupled Baselineconfiguration, the system maintains a great deal ofdesigned-in flexibility. Several of the pallet locationsare reserved for project-specific pallet installations.The modification and integration of project specificresearch equipment is the quintessential goal of theaircraft and the TRS.

Many of the evolving research efforts targeted to flyon ARIES require a real-world, out-the-window


view,or the abilityto fully controltheaircraftthroughanygivenphaseofflightincludingtake-off,landingroll-outandtaxi.EvenwiththeeventualAFD,theleftseatoftheforwardflightdeckis theonlylocationthatallowsboth.Theconceptof theFlightDeckResearchStation(FDRS)wasdevelopedto accommodatetheseresearchrequirements,yetmaintainthenormalutilityoftheaircraft,andprotectthelevelof safetyandoversightneededto conductviableresearchoperations.TheFDRSisessentiallyareconfigurationoftheleftsideoftheforwardflightdeckfortestsubjectsto evaluateflightsystemsandoperationalprocedures.As partof this concept,severalmodificationsandoperationalcontrolshavebeenimplementedontheaircraftandarediscussedbelowinmoredetail.

Theaircrafthasundergoneseveraldistinctphasesinreachingits currentconfiguration.In ordertocontinueto advancethe researchprograms,modificationphaseshavebeeninterspersedwithperiodsofresearchoperations.TheaircraftachievedanoperationalTransportResearchSystem(TRS)inJune1997.TheinitialTRScapabilitiesallowedthecompletionof the Low VisibilityLandingandSurfaceOperations(LVLASO)experimentin JulyandAugustof 1997.Completionof theUncoupledBaselineTRSwasaccomplishedinDecember1998,allowingthedisplayofexperimentalguidancetotheFDRS.Followingthis,theaircraftcompletedtheWinerRunwayOperationsresearchin February1999.ThethirdmajorphaseofmodificationfortheTRSresultedin the currentCoupledBaselineconfiguration.TheCoupledBaselineallowsfortheaircraftto be coupledto and flown usingexperimentalguidance.ThefirstresearchprogramtomakeuseoftheCoupledBaselinewastheAirborneInformationforLateralSpacing(AILS)flightsduringAugust1999.

Duringtheaircraft'stransformationamajorityofthemodificationswerecompletedbyNASAcivilservantandcontractorpersonnelat LaRC.Severalmajorstructuralmodificationshavebeencompletedduringscheduledheavymaintenancebycontractfacilities.Theupcomingintegrationof theaft flightdeckrepresentsthefinalstageof thecurrentlyplannedBaselinemodifications.This installation,incombinationwithmultiplesystemsupgrades,willrequiresomerearrangementof theBaselinepalletlocationsasshownin thispaper,butwill retain orenhance all the existing capabilities. At the time ofthis writing, this effort is in the final design reviewsand dedicated installation efforts are scheduled to

begin in summer 2003.

ARIES Coupled Baseline Configuration

The cabin layout for the current Coupled Baselineconfiguration is show in Figure 5. The two mainelements are the Flight Deck Research Station andthe Transport Research System. The followingsections detail each of these elements respectively.

VIDEO/TEST DIRECTOR DATA PROCESSING

AND DISPLAY- SYSTEMONYX OPERATOR

VIDEO RECORDINGFLIGHT MANAGEMENT

TECHNOLOGYSYSTEM SGI ONYX

FLIGIIT DECK EXPERIMENTAL

RESEAIlCIt POWER / VIDEO ROUTING SWITCH

STATION [ DISTRIBUTION [

FLIGtIT SYSTEMS ] DATA ACQUISITION SYSTEM/

INTERFACE [ DO CONCENTRATOR

WIRE INTEGRAI'ION UNII

Figure 5: ARIES Baseline Cabin Layout

Flight Deck Research Station (FDRS)With the Coupled Baseline configuration, the FFD'sleft side primary flight display (PFD), navigationdisplay (ND), and control display unit (CDU) can bereplaced with research units that can be driven byexperimental inputs from the Onyx computer. Anexperimental head up display (HUD), shown inFigure 7, has also been installed, providing another

method of displaying experimental displays to anevaluation pilot. Additionally, the experimentalsystem can provide inputs to the ship's flight controlcomputers, thus allowing automatic flight, includingcoupled autolands. Whether flown manually orcoupled, the FDRS provides an evaluation pilot the

ability to assess the desired research concepts, bethey advanced displays, cockpit procedures, oraircraft performance.

Figure 6: The 757 features a Flight Deck ResearchStation on the left, or captain% side of the cockpit.


Toensuretheabilityoftherightseatsafetypilottoadequatelyprotecttheaircraftfromundesiredevents,severalstandbyinstrumentshavebeenaddedtotheinstrumentpanel.(MostofthesemodificationsweredrivenbythebasicdesignphilosophyoftheB-757,wheresystemsfailuremodesareall basedonensuringsufficientcontrolfor the left seat.)Inadditionthecenterislestandhasbeenreconfiguredfortheinstallationof anadditionalCDU,allowingforasecondsafetypilottositinthemiddlejumpseatandbeabletoprovideinputintoeithertheship'sortheresearchnavigationsystem.A fourthjumpseatbehindtherightpilotseatprovidesseatingfor aresearcherorobserver.

Figure 7: The FDRS experimental HUD

Transport Research System (TRS)Fourteen test pallets/research workstations are in the

baseline layout as shown in Figure 5. Others areadded depending on research needs. There are twentyavailable pallet locations. Pallet stations aresequentially numbered by location, starting with theodd numbered pallets on the port side of the aircraftand the even numbered pallets on the starboard side.

1. Flight Systems Interface2. Flight Management6. Onyx Computer7. Experimental Power Distribution7A. Wire Integration Unit8. Onyx Operator9. I/O Concentrator

10. Video #1 (Video/Test Director)11. Data Acquisition System (DAS)12. Data Processing & Display Station (DPDS)13. Video #3 (Video Routing Switch)14. Video #2 (Video Recording)15 Technology Transfer Area 1 (TTA1)16 Technology Transfer Area 2 (TTA2)

Stations 3, 4, 18, and 19 have been used forindividual project pallet installations at various times.The cabin area of stations 3 and 4 has been designedfor the eventual installation of an aft research flightdeck.

Standard audio, video and time functions exist at allmanned pallet locations. Each of these pallets has anaudio panel that provides the pallet occupants withthe ability for two-way communications over any ofthe four intercoms and two of the four radio sources.

The remaining two radios can be monitored byanyone, but only the flight deck crew is able totransmit. Each manned pallet also contains two 8"monitors that allow the pallet operators to select andmonitor video images for enhanced situationalawareness. Additionally, each pallet has an electronictime display driven by GPS-provided time code and adiscrete event marker button that can be used to mark

events on the data recording.

Pallet #1 - Flight Systems Interface

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This pallet provides flight controlssystems, thrust managementsystems, and the Pilot SelectionPanel (PSP) monitoring. (The PSPis located in the flight deck and isthe switch that selects between the

standard ship's control and theexperimental control.) Thispallet's systems provide the

FDRS experimental displays (PFD and ND) andExperimental Display Control Panel (EDCP) withpower and setup control, as well as providing theHUD power, and signal conversion control andmixing. This station will play a major role in theintegration and operation of the proposed AFD flightcontrols interface unit (FCIU). A secondary locationfor the aircraft's Crew Chief, who would normally flyin the cockpit, is also provided at this pallet. Duringcertain types of operations where a third safety pilot

or research observer is required in the flight deck, theCrew Chief can be repositioned to the number onepallet where he has appropriate communications andmonitoring capability.

Pallet #2 - Flight Management

Operators at this pallet oversee and manipulate theexperimental Flight Management and Navigation

systems. The pallet houses theexperimental Flight ManagementComputer (FMC) and a secondexperimental CDU, as well astwo Ashtech GPS receivers, and aprototype WAAS GPS receiver,any of which can be used toprovide positional information tothe experimental system. The

pallet also controls three differential GPS (DGPS)datalink radios that can also be used to transmit or

receive a pseudo- Automatic DependentSurveillance-Broadcast (ADS-B) signal.


Pallet #6 - Onyx ComputerThis is the primary researchcomputer on the aircraft. Itdrives the research displays andserves as the experimental FlightManagement System (FMS)and/or the Flight ControlComputer (FCC). The computeris a Silicon Graphics Inc. Onyx

mainframe that has been specially re-housed andflight hardened. It has eight Computer ProcessingUnit's (CPU's) @ 200 MHz each and three graphicpipes capable of driving 18 displays at1024x768x60hz. The computer draws 7kva powerand requires 850 cubic feet per minute cooling air at40 degrees Fahrenheit.

Pallet #7 - Experimental Power DistributionThis pallet is the interface between the aircraft

electrical system generators and the experimentalsystem. It controls the distribution of electrical power

to the individual research systempallets and components throughswitches and circuit breakers

located on the pallet.Experimental system power canbe disconnected with an

emergency shutdown switchlocated in the cockpit. Status ofthe research system electrical

loading can be monitored using the panel meters andanalyzers located within the pallet. The researchsystem receives power inputs from each of the twoengine generators (90 kva), auxiliary power unit (90

kva), and external power sources. Researchequipment located in the forward cargo bay isolates28 volts DC and 115 VAC, 60 Hz from the l15V AC400 Hz bus generators. The research electrical systemthen distributes power via two power buses to eachpallet station. Each research pallet station is

interfaced to the research power buses through a localpower sub-panel to distribute power on that pallet.All research power wiring is distributed to the palletsunder the cabin floor to isolate it from research

signal/data wiring that is routed in the overhead cabletrays.

Pallet #7A - Wire Integration UnitThis unmanned pallet is the central wiring point forall signals used by the experimental system. Its patchpanel configuration allows for relatively easyreconfiguration of multiple wire integration unit's(WIU) sub-chassis for patching of signals to variouspallets

Pallet #8 - Onyx OperatorThe Onyx Operator stationserves to monitor and control

the Onyx computer. Operatorsstart, monitor, and stop theresearch software running inthe Onyx computer. Thissoftware typically runs theexperimental displays andmay also run any experimentalalgorithms or calculations

required by the research.

Pallet #9 - I/O Concentrator

The I/O Concentrator pallet is the primary signalconcentration point for the aircraft's subsystems

ARINC 429 data busses; 757research sensors, researchcomputer, Data AcquisitionSystems (DAS), and otherexperimental system analog,digital, synchro and ARINC 429signals. Utilizing a suite of VMEcards and a 133 MHz MCP604

PowerPC processor, the palletconverts the above signal

information to and from the SCRAMNet (SharedCommon Random Access Memory Network)protocol that is used when transmitting data over theresearch system's fiber optic network ring. TheSCRAMNet maximum throughput is 16 MB/sec. Thepallet houses a quad switch junction box that formsthe research system's fiber optic network ring. Inaddition, it provides high-fidelity IRIG-B time to the

research system by utilizing a Time FrequencyProcessor (TFP) card whose internal oscillator istrained by signals from a GPS receiver

Pallet #10 - Video #1/Test Director

This pallet serves a dual role. It provides the primary

monitoring and control station for the entire videosubsystem (total of 3 pallets).In addition, it serves as theFlight Test Director station,providing the Test Directorwith communications

capabilities and enhancedsituational awareness with atotal of eleven video monitors

and a computer for datamonitoring and GPS-drivenpositional display. The Test

Director has a separate communications panel toallow independent communications on any availableradio and intercom channel. The panel also includes a


tunableVHFradio(w/enableswitchwhichallowsanyaftcabinstationstotransmitviathisVHF),andapublic address handset for intra-aircraftannouncements.As thevideosystemcontrol,thepalletusesninemonitorsfor verifyingrecordedimagesandtwo feedbackmonitorscapableofselectinganyofthefourcameraandfourcomputergeneratedvideosources.Thepalletalsohousescameracontrolunitsforthefourcamerasources,thetailcameraheaterandcontroller,andavideoselectorswitchthatallowsanyoftheaudiosourcesonboardtoberecordedonanyofthevideorecordings.

Pallet # 11 - Data Acquisition System (DAS)The DAS provides the dataacquisition and storage ofaircraft parameters from analogsensors, SCRAMNet fiber opticlink, and the aircraft 429 busses.A setup computer is used forsystem setup, control, andmonitoring. The heart of theDAS is the Advanced Airborne

Test Instrumentation System (AATIS) pulse codedmodulation (PCM) system. The AATIS has thecapability to monitor 96 analog data channels and192 discrete inputs. Direct connection to analogsensors is via the wire interface unit (WIU) and it'sassociated signal-conditioning integrated circuitry.The DAS is connected to the aircraft 429 busses via acustom built 429 interface to the Advanced Airborne

Test Instrumentation System (AATIS). The system iscurrently configured to record 1,000 aircraftparameters to magnetic tape using a Mars II taperecorder. Parameters can be recorded at a bit rate of

555,555 bits/second for 20 hours at sampling rates of200, 50, 25, 12.5 and 6.25 Hz. The system isconnected to the research system via SCRAMNet+fiber optic link.

Pallet #12 - Data Processing & Display Station

(DPDS_The DPDS takes serial PCM

data, processed and recorded byDAS, and converts any of 1,000data parameters to engineeringunits (i.e., altitude in feet) fordisplay to a researcher at theDPDS pallet in real-time.The system provides variouseasily configured displayoptions, including plots, tabulardata, time histories, and many

different graphical formats. The display can be drivenby real-time data, or used to play back previouslyrecorded data. The DPDS can record as many as 500

parameters per second on an optical disk. The filescan be moved to a floppy disk for later use by anexperimenter or it may be sent to any device on theaircraft LAN. Once on the ground, the files may betranscribed to a CD for permanent storage. Thesystem controller is a Force Computer 68040processor installed in a VME chassis runningVxWorks.

Pallet #13 - Video #2

This is the primary video palletfor recording the video sourcesand for scan converting thesignals into the correct outputformat. The system is capable ofrecording all of the videosources and contains a playbackfeature on VCR #1 for playingback video onboard the aircraft.

The pallet contains 8 Super VHSvideo recorders, 4 YEM scan

converters for converting the computer-generatedsources, and 4 SONY scan converters for convertingthe video sources to the correct format for telemetry.

Pallet #14 - Video #3

The Video three pallet providesswitching for the videosubsystem and recording of allaudio sources. Two RM5000

routing switch matrices providethe ability to switch theappropriate video sourcesthroughout the aircraftDiagnostic and troubleshooting

equipment as well as multiple video distributionamplifiers for duplicating various video sourcesreside on this unmanned pallet. A Stancil audiorecorder continuously records all audio sources,including the cockpit voice audio.

Pallets #15 & 16 - Technology Transfer Area (TTA)#1 #2This area allowsresearchers to

accommodate up to18 onboard

observers, andprovides them withthe appropriateinformation tofacilitate the real-

time transference of technological knowledge duringvarious flight tests. Each pallet has a 20" flat-paneldisplay that can be configured to display the desiredresearch images. Additionally, two 8" monitors


locatedon eachpalletallowsthemonitoringofadditionalimages.AudiospeakersareutilizedduringonboardplaybackfromVCR#1.Theseprovideanaudiblesourcefordemonstrationsin theTTA.TheTTAareaalsoprovidesspaceforadditionalresearchpalletlocations.

ARIES's Accomplishments

Since ARIES was purchased in 1994 the aircraft hascompleted a variety of research efforts, most ofwhich have been focused at furthering the efficiency,effectiveness, and safety of civil transport aviation.These studies have helped develop the technologythat will enable the aviation industry to reach the

national goal, set by President Clinton, of reducingthe fatal aircraft accident rate by 80% in ten yearsand 90% in 25 years. A discussion of ARIES'involvement in some of these programs follows.

High Intensity Radiated Field Sources - (HIRF) 4

In February 1995, the NASA LARC conducted aseries of aircraft tests aimed at characterizing theelectromagnetic environment (EME) in and around aBoeing 757 airliner. As the complexity and criticalityof the functions performed by the on-boardelectronics increases, so does concern about thevulnerability of these systems to electromagneticinterference (EMI). Sources of EMI that are ofparticular concern are man-made radio frequency(RF) sources generated external to the aircraft, suchas radar and radio transmitters. These potentialsources of EMI are collectively known as HIRF orHigh Intensity Radiated Field sources.

During the EME flight test, measurements were madeof the electromagnetic energy coupled into theaircraft and the signals induced on select structures asthe aircraft was flown past known RF transmitters.The aircraft was instrumented with an array ofsensors positioned to study the electromagneticcoupling characteristics and shielding effectivenessof the aircraft's three main compartments; the flightdeck, the avionics bay, and the passenger cabin.ARIES flew a total of 56 data runs against four RFsources. Predetermined flight profiles were flown toensure that electromagnetic energy impinged uponthe aircraft fuselage at various angles of incidence.The flight test provided data used to validatecomputational techniques for the assessment ofelectromagnetic effects in commercial transportaircraft. Such knowledge will improve the designprocess, resulting in more robust and cost effectivedesigns.

Low Visibility Landing and Surface Operations(LVLASO) and Runway Incursion PreventionSystem (RIPS) 7A main focus of the research conducted at Langley is

the investigation of technology that will improve thesafety and efficiency of aircraft movements on thesurface during the operational phases of landingrollout, turn-off, inbound taxi and outbound taxi. Inpoor visibility, at night, or at unfamiliar airports,operating safely on the airport surface at rates equal(or better) to those in clear weather requires that bothpilots and controllers be provided with supplementalinformation about the state of the airport and relevanttraffic. It is hoped that by providing supplementalguidance and situational awareness information toboth pilots and controllers, safety margins will beincreased and operations can be maintained at VisualMeteorological Conditions (VMC) capacities,regardless of actual visibility conditions.

Initially conducted as part of the Low VisibilityLanding and Surface Operations (LVLASO)program, this effort has evolved into what is nowcalled the Runway Incursion Prevention System(RIPS). The change in name represents aprogrammatic evolution from a joint research projectworking capacity issues to a national effortaddressing a critical safety issue. Certainly thedemands for air travel continue to grow, but reportedsurface incidents have continued to increase at an

alarming rate. Hazardous runway incursions ratesincreased by more than 50 percent and at least fivefatal airport surface accidents occurred from 1990-1999. In 2000, 431 surface incidents were reported,an all-time high. Reduced visibility was a

contributing factor in many of these accidents andincidents.

Since 1996, ARIES has participated in a series offlight experiments and demonstrations supporting thiseffort. ARIES has performed flight and taxi

operations for LVLASO at the Hartsfield AtlantaInternational Airport in 1997, and for RIPS at theDallas-Ft. Worth Airport in 2000. To complete theLVLASO and RIPS testing, ARIES was equippedwith experimental displays that were designed toprovide flight crews with sufficient information toenable safe expedient surface operations in anyweather condition down to a runway visual range(RVR) of 300 feet. In addition to flight deck displaysand supporting equipment onboard the B-757, therewere also ground-based components of the systemthat provided for ground controller inputs and theuplink of surveillance of airport surface movements.The prototype system consisted of several advancedtechnologies that made up an integrated


Figure 8: RIPS HUD and Electronic Map Displays

communication, navigation, and surveillance (CNS)system. Airport Surface Detection Equipment-3(ASDE-3) data was fused with other surveillance dataand was provided to both the controller and the testaircraft. Various algorithms analyzed the potential forincursions and generated appropriate alerts. Thisspecific implementation was designed to showwhether the concept was both operationally andtechnically feasible.

for similar potentially hazardous runway conditions,and establishing reliable correlation between groundvehicle friction measurements and aircraft brakingperformance. Accomplishing these objectives wouldnot only give airport operators a better way toevaluate runway friction and maintain acceptableoperating conditions, but would also contribute toreducing traction-related aircraft accidents.

These technologies were tested using the ARIESaircraft with both NASA test pilots and commercial

757 captains acting as evaluation pilots. Theintegrated ground and airborne components resultedin a system that has the potential to significantlyimprove the safety and efficiency of airport surfacemovements, particularly as weather conditionsdeteriorate. Data resulting from these tests are being

used to enhance the system's capabilities for futureimplementations and to develop and validaterequirements for using these technologies in thefuture.

Runway Winter Operations 8

Runway water, ice or snow was a factor in more than100 airplane accidents between 1958 and 1993. Mostof those accidents involved fatalities. In support ofthe national effort to reduce the fatal aircraft accident

rate, the NASA Langley Research Center partneredwith Transport Canada and the FAA in a five-yearwinter runway friction measurement program. Theon going research effort uses instrumented aircraft,friction-measuring ground vehicles and test personnelfrom around the world. The major objectives of theJoint Winter Runway Friction Program includecoordinating different ground vehicle frictionmeasurements to develop a consistent friction scale

Figure 9: NASA B757 makes a test run on a snowyrunway in Michigan.

Since testing started in January 1996, fiveinstrumented aircraft, including the Langley 737 and757, and 13 ground test vehicles have been evaluatedat sites in Canada, the United States, and Norway,completing nearly 400 instrumented aircraft test runsand more than 8,000 ground vehicle runs. Tests havebeen performed on a variety of runway conditions,where researchers have taken manual measurementsto monitor conditions before and after a test run

series. From this substantial friction database,engineers have developed an international runway


frictionindex(IRFI)tostandardizefrictionreportingfrom differentdevicesand to minimizepilotdifficultiesin makingcriticaltakeoffandlandingdecisions.An IRFI methodologystandardthatdefinesprocedureandaccuracyrequirementsisunderreviewforapprovalbyaninternationalcommittee.

Theoverallresultsfromthisprogramwill increaseaircraftsafetyandthecapacityof airportswherewinterconditionsaresevere.Someoftheresultsandtestproceduresmayalsoapplytohighwaysafety.

Airborne Information for Lateral Spacin_ (AILS)9

In 1999 NASA and Honeywell collaborated on ajoint effort to develop concepts, procedures, andsupporting technology to safely enable closelyspaced, independent, parallel approach operations.The Airborne Information for Lateral Spacing (AILS)system expanded on existing communication andnavigation technology to allow planes to land safelyin bad weather on parallel runways spaced as close as2,500 feet. Currently, the minimum runwayseparation during low visibility is 4,300 feet, whichmeans that some of the nation's biggest airports have

to shut down one of their closely spaced runwayswhen weather conditions deteriorate. Among thefacilities AILS technology could impact are airportsin Detroit, Seattle and Minneapolis.

evasive maneuver. Fewer bad-weather delays wouldmean financial savings for the airline industry, moreefficient airport operations, and travelers arriving attheir destinations on schedule.

Synthetic Vision 11Synthetic Vision System (SVS) research is beingconducted as a potential mitigation to the number oneaviation safety hazard, Controlled Flight Into Terrain(CFIT), and the growing safety problem of runwayincursions. SVS utilizes integrated, high-resolutiondatabases and photo-realistic display concepts toprovide improved situational awareness and pathcontrol. Used in conjunction with integritymonitoring sensors such as radar or Forward-LookingInfra-Red (FLIR), Synthetic Vision Systems have thepotential to provide substantial safety andperformance benefits.

The NASA B-757 ARIES and a Honeywell

Gulfstream IV (G-IV) were used in the flight testeffort. Honeywell provided the airborne DGPS,ADS-B datalink, Traffic Alerting and CollisionAvoidance System (TCAS) II w/AILS algorithms,and ground DGPS components. During the flight-testing, both aircraft would be set up on closely-spaced parallel approach paths when the Gulfstreamwould begin to "stray" off course toward the B-757.With the AILS system, the aircraft would "talk" toeach other via the ADS-B. DGPS signals providedprecise information about each plane's location. TheAILS algorithms would monitor the intrusion andtrigger multiple levels of alerts. Ultimately, ifrequired, the system could initiate an automaticallyflown evasive maneuver. Validation flights werecompleted at the NASA Wallops Flight Facility andin-flight demonstrations of the system werecompleted at Minneapolis-St. Paul InternationalAirport in November 1999 for FAA officials andother Government and industry representatives. Thedemonstrations showed that safe weather-

independent operations with closely-spaced runwayscould be viable through the simultaneous use of the,the AILS alerting fimctions, and simple, consistentpilot procedures that included a basic emergency

Figure 1O: SVS HUD image

The ARIES aircraft has been a key player in the SVSwork completed at the NASA LaRC. Photo-realisticconcepts have been successfully flown at Dallas-Ft.Worth in 2000, and Eagle-Vail, Colorado in 2001.Using GPS positioning, the synthetic vision softwarecreates a three-dimensional map of the surrounding

terrain. As the aircraft's position changes, this mapchanges accordingly, providing the pilot with anaccurate, 3D, moving display in the cockpit. Inaddition to the terrain, runways, path guidance, andother aircraft can also be integrated into the display.Digitally superimposing aerial photographs gives theimages a photo-realistic look. These images can bepresented to the pilot on either a head down display(HDD) or a head up display (HUD). Themonochromatic HUD uses outlines and shading tocreate the 3D terrain effect. Figure 10 is a HUDimage showing the mountainous terrain aroundEagle, Colorado.


Figure 11: SVS HDD image

The HDD projects full color images, making the mostof the photo quality. Figure 11 shows a similar imageas displayed on the HDD. Note the image detail,including buildings and streets.

Recent terrain database information has been

compiled using images collected by the Shuttle RadarTopography Mission (SRTM) conducted in February2000. With this increased database information and

the ever-increasing computational power available,the ability of the technology is expected to growsubstantially in the coming years. The benefits ofSVS will undoubtedly be realized in the coming

generations of aircraft, but the ability to retrofitSynthetic Vision Systems into current glass and non-glass cockpits is proving to be a viable alternativeand will provide future safety and performancebenefits to the existing fleet as well.

Summary

The NASA Langley Research Center operates ahighly modified B-757 aircraft to further theAgencies aviation research objectives. The aircraft'sexperimental system can be re-configured toaccommodate a wide variety of advancedaerodynamic, airframe, and avionic systems testing.The aircraft is just one part of the integrated researchprocess and facilities at Langley that allowsresearchers to take their concepts and programs easilyfrom the simulator or laboratory straight to flighttesting.

Acknowledgements

This paper is an overview of a variety of effortsconducted over the span of many years by a largenumber of individuals at the NASA Langley

Research Center. As such, it is largely a compilationof works by a number of different writers. In puttingthis together the author would like to acknowledgethe help and input of the researchers and engineerswho were directly responsible for the variousprograms and systems. The collective goal was todocument the evolution, capabilities, and operationalrecord of this unique national asset. Special thanks toKathy Barnstorff Randy BaileyLucille Crittenden Stella HarrisonKevin Shelton Denise Jones

Barbara Trippe Tom Yager

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aries: nasa langley's airborne research facility michael s

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