The Role of Aircraft Simulation in Improving Flight Safety … … · · 2013-06-27The Role of...

NASA/TM-2002-210731

The Role of Aircraft Simulation in Improving Flight Safety Through Control Training

Karla S. Shy, Jacob J. Hageman, and Jeantette H. LeNASA Dryden Flight Research CenterEdwards, California

August 2002

The NASA STI Program Office…in Profile

Since its founding, NASA has been dedicatedto the advancement of aeronautics and space science. The NASA Scientific and Technical Information (STI) Program Office plays a keypart in helping NASA maintain thisimportant role.

The NASA STI Program Office is operated byLangley Research Center, the lead center forNASA’s scientific and technical information.The NASA STI Program Office provides access to the NASA STI Database, the largest collectionof aeronautical and space science STI in theworld. The Program Office is also NASA’s institutional mechanism for disseminating theresults of its research and development activities. These results are published by NASA in theNASA STI Report Series, which includes the following report types:

• TECHNICAL PUBLICATION. Reports of completed research or a major significantphase of research that present the results of NASA programs and include extensive dataor theoretical analysis. Includes compilations of significant scientific and technical data and information deemed to be of continuing reference value. NASA’s counterpart of peer-reviewed formal professional papers but has less stringent limitations on manuscriptlength and extent of graphic presentations.

• TECHNICAL MEMORANDUM. Scientificand technical findings that are preliminary orof specialized interest, e.g., quick releasereports, working papers, and bibliographiesthat contain minimal annotation. Does notcontain extensive analysis.

• CONTRACTOR REPORT. Scientific and technical findings by NASA-sponsored contractors and grantees.

• CONFERENCE PUBLICATION. Collected papers from scientific andtechnical conferences, symposia, seminars,or other meetings sponsored or cosponsoredby NASA.

• SPECIAL PUBLICATION. Scientific,technical, or historical information fromNASA programs, projects, and mission,often concerned with subjects havingsubstantial public interest.

• TECHNICAL TRANSLATION. English- language translations of foreign scientific and technical material pertinent toNASA’s mission.

Specialized services that complement the STIProgram Office’s diverse offerings include creating custom thesauri, building customizeddatabases, organizing and publishing researchresults…even providing videos.

For more information about the NASA STIProgram Office, see the following:

• Access the NASA STI Program Home Pageat

http://www.sti.nasa.gov

• E-mail your question via the Internet to [email protected]

• Fax your question to the NASA Access HelpDesk at (301) 621-0134

• Telephone the NASA Access Help Desk at(301) 621-0390

• Write to:NASA Access Help DeskNASA Center for AeroSpace Information7121 Standard DriveHanover, MD 21076-1320

NASA/TM-2002-210731

The Role of Aircraft Simulation in Improving Flight Safety Through Control Training

Karla S. Shy, Jacob J. Hageman, and Jeantette H. LeNASA Dryden Flight Research CenterEdwards, California

August 2002

National Aeronautics andSpace Administration

Dryden Flight Research CenterEdwards, California 93523-0273

NOTICE

Use of trade names or names of manufacturers in this document does not constitute an official endorsementof such products or manufacturers, either expressed or implied, by the National Aeronautics andSpace Administration.

Available from the following:

NASA Center for AeroSpace Information (CASI) National Technical Information Service (NTIS)7121 Standard Drive 5285 Port Royal RoadHanover, MD 21076-1320 Springfield, VA 22161-2171(301) 621-0390 (703) 487-4650

THE AIRCRAFT SIMULATION ROLE IN IMPROVING FLIGHT SAFETY THROUGH CONTROL ROOM TRAINING

Karla S. Shy*, Jacob J. Hageman† and Jeanette H. Le‡

NASA Dryden Flight Research Center Edwards, California

Abstract

NASA Dryden Flight Research Center uses itssix-degrees-of-freedom (6-DOF) fixed-base simulationsfor mission control room training to improve flightsafety and operations. This concept is applied tonumerous flight projects such as the F-18 High AlphaResearch Vehicle (HARV), the F-15 Intelligent FlightControl System (IFCS), the X-38 Actuator Control Test(XACT), and X-43A (Hyper-X). The Dryden 6-DOFsimulations are typically used through various stages ofa project, from design to ground tests. The roles of thesesimulations have expanded to support control roomtraining, reinforcing flight safety by building controlroom staff proficiency. Real-time telemetry, radar, andvideo data are generated from flight vehicle simulationmodels. These data are used to drive the control roomdisplays. Nominal static values are used to completeinformation where appropriate. Audio communication isalso an integral part of training sessions. This simulationcapability is used to train control room personnel andflight crew for nominal missions and emergencysituations. Such training sessions are also opportunitiesto refine flight cards and control room display pages,exercise emergency procedures, and practice controlroom setup for the day of flight. This paper describesthis technology as it is used in the X-43A and F-15 IFCSand XACT projects.

1American Institute of Aero

*Simulation Engineer†Simulation Engineer, Member‡Simulation Engineer

Copyright 2002 by the American Institute of Aeronautics andAstronautics, Inc. No copyright is asserted in the United States underTitle 17, U.S. Code. The U.S. Government has a royalty-free licenseto exercise all rights under the copyright claimed herein forGovernmental purposes. All other rights are reserved by the copyrightowner.

Notice: The use of trade names or names of manufacturers in thisdocument does not constitute an official endorsement of suchproducts or manufacturers, either expressed or implied, by theNational Aeronautics and Space Administration.

Nomenclature

CVT current value table

DOF degrees-of-freedom

GRIM Global Real-Time Interactive Map

GUI graphical user interface

HARV High Alpha Research Vehicle

IFCS Intelligent Flight Control System

IFPC Integrated Flight Propulsion Control System

MCC Mission Control Center

NT operating system, Microsoft Corp. Redmond, Washington

OTW out-the-window

PAGE Project Application Graphics Executable

PCM pulse code modulation

PDF Parameter Description File

PDS Parameter Display Software

RES Real-Time Ethernet Server

RS 232 asynchronous serial data stream, ITU-T international standard

SID simulation interface device

TMF test maneuver feature

TRAPS Telemetry and Radar Acquisition Processing System

UNIX operating system, The Open Group, San Francisco, California

XACT X-38 Actuator Control Test

VME Versa Module Eurocard

nautics and Astronautics

Introduction

Flight safety and mission success are two primaryobjectives in flight-test programs at NASA DrydenFlight Research Center (Edwards, California). Manyprocesses are exercised through the duration of a flightprogram to ensure that both objectives are met by allresearch disciplines and support facilities. The Drydensix-degrees-of-freedom (6-DOF) simulation has longbeen a valuable tool for achieving mission success. Itplays a role during vehicle design and development,ground testing, mission planning, and postflight dataanalysis. In the last decade, simulation capabilities wereexpanded to contribute towards flight safety bysupporting control room training.

One way to ensure flight safety is to gather the controlroom staff with the flight crew, connected through audiocommunication, to simulate a day of flight. With thesimulation driving the Mission Control Center (MCC),the control room personnel and flight crew can exercisenominal missions, emergency situations, andcommunications protocol. Such simulated flight provesespecially beneficial for projects with few flights, orprojects with new engineers who have little or noprevious control room experience. These sessions giveboth primary and backup personnel the opportunities todevelop familiarity with the control room setup, thedisplays, the flight cards, emergency procedures, and theoverall dynamics in the control room on the day offlight. The training also benefits people behind thescenes who are setting up the control room forday-of-flight operations. The MCC support staff canexecute many of their control room procedures andevaluate their readiness and efficiency during thesetraining exercises.

These training sessions are also opportunities toimprove control room displays. Prior to formal controlroom training, the simulation can be used to drive thedisplay pages, both statically and dynamically, to checkfor both aesthetics and function. This can be done eitherwith the displays running in the simulation laboratory,or with the data connection between the simulation andthe actual control room. The final test is to use thesedisplays during a day-of-flight training scenario in orderto evaluate their effectiveness during an actual mission.Engineers can then verify that the data displayed arepertinent, easy to analyze, and function well with theprocedures in the flight cards. Refinements to better suitcontrol room displays to flight objectives, can then bemade, contributing to both the safety and success of themission.

Control room training using flight simulation is also achance to refine the flight cards for the mission. For anominal piloted mission, time is critical, emphasizingthe necessity for a well thought out, efficientprogression through the flight test. During a simulatedmission, various sequencing combinations can easily beperformed to find the optimum order for maneuvers tomaximize the amount of important data gathered whileminimizing fuel usage. In the realm of flight safety, thesmooth and timely execution of emergency proceduresis even more vital. Safety demands emergencyprocedures be in place for all imaginable off-nominalsituations. It also requires that the project procedureswork effectively and efficiently as intended. Withsimulation, failures can be introduced, to test thatappropriate and effective emergency procedures are inplace.

This paper describes how control room training thatuses Dryden simulations is applied in the X-43A(Hyper-X) project and the Intelligent Flight ControlSystem (IFCS) and X-38 Actuator Control Test (XACT)projects. The IFCS and XACT are both flown on theF-15 research aircraft. These programs demonstrate howDryden consolidates resources between the controlroom and simulation facilities to provide a valuablecapability that meets project objectives. In addition,these efforts reduce both cost and time spent forresource development of tools that can be usedcenter-wide, and expand capabilities of Drydensimulation, from vehicle design to preparation for flight.

Background

This section discusses the simulation environmentand the Mission Control Center, and provides anoverview of the capabilities and uses of these facilities.This information broadens understanding and informsreaders regarding Hyper-X and F-15 control roomtraining configurations.

Simulation Environment

The Dryden 6-DOF simulation varies in complexityto reflect the requirements of the flight researchprogram. Simulations are designed to be operable by asingle user, whether it be a batch version running on aworkstation, or a full pilot-in-the-loop configuration.Simulations can also integrate with the actual flighthardware, or software in the hardware-in-the-loopconfiguration, or both. The fullest use of a simulation isin the aircraft-in-the-loop configuration, where thesimulation is integrated with the aircraft itself.

2American Institute of Aeronautics and Astronautics

Each project may require any or all of these levels ofsimulation complexity. The hardware configurations canbe designed specifically for a project, using a dedicatedlaboratory and simulator cockpit (such as the case forthe F-15 simulation), or the project may choose to use ageneric glass cockpit and heads-up displays such as inthe case for Hyper-X. Regardless of the level ofcomplexity, data monitoring tools are available in thereal-time simulation environment, including mechanicalstrip charts, simulated heads-up graphics, and controlroom displays, as well as a variety of data analysissoftware.

The simplest configuration of a typical simulation isthe batch mode, also referred to as either an “allsoftware” mode or a “non-real-time” mode. The onlyhardware required for the batch simulation is a UNIXworkstation. The applications for a batch simulationinclude development and testing of aircraft models,evaluation of aircraft performance, Monte Carloanalysis, and development of new simulation features tofacilitate certain applications, if necessary. The batchsimulation can also be used to develop procedures forground tests that use the simulation. The simulation canalso serve as a tool to evaluate the test data. Engineerscan run a simulation in batch mode at their desk for anyof these applications. A graphical user interface (GUI) isprovided, allowing easy access to information

calculated in the simulation and control of the variousfunctions.

The real-time mode supports configurations thatinvolve a pilot-in-the-loop, hardware-in-the-loop, oraircraft-in-the-loop. The key differences between batchand real-time modes are the addition of a scheduler andthe ability to communicate with the desired hardware. Inmost cases the same program executable is used for bothmodes, with flags provided at the start determining thedesired configuration. Figure 1 shows an illustration ofthe typical simulation hardware setup.

The pilot-in-the-loop simulation is used to evaluateaircraft performance and stability, test experimentalobjectives, conduct mission planning and rehearsals,perform overall pilot system assessment, and conductcontrol room training and checkout of control roomdisplays. This simulation can also be used during theearly stages of simulation development, to design theguidance and controls for autonomous vehicles. In thepilot-in-the-loop configuration, the simulation interfacesto a cockpit that uses the Dryden simulation electricstick for pilot inputs and a control panel for push-buttoncontrol of the simulation.

Visual cues in the pilot-in-the-loop configurationinclude heads-up graphics and a heads-down instrumentpanel. The heads-up graphics, projected onto a


Figure 1. Simulation environment (hardware configuration).1

2.5-meter diagonal projection screen, includes theterrain, roads, and several base facilities (such asrunways, tower, and hangars). The graphics also containa three-dimensional model of the vehicle witharticulated flight controls surfaces and a heads-updisplay. From the simulation, the user can choose fromseveral viewpoints including an out-the-window (OTW)view, a ground fixed view (such as from the tower orrunway), an aircraft fixed view from a chase aircraft, ora view from some other fixed point in space. Thecockpit heads-down instrument panel can vary from afull analog replication of the actual aircraft cockpit to aglass-cockpit display with an 8-ball and genericinstruments.

Control room displays can also be run in thesimulation real-time environment for additional datamonitoring capability, either in the laboratoryenvironment or during ground tests. Engineers can usethis environment to design and evaluate theeffectiveness and functionality of control room displays.This environment also gives the users an additionalopportunity to familiarize themselves with thesedisplays in preparation for the day of flight.

Strip charts, driven by simulation data, allow theengineers to monitor data and evaluate various dataconfigurations for use in the control room. In the case ofthe F-15 simulation laboratory, the same model of stripcharts are used as in the control room, allowing users tosave the desired configuration to a disk for use at eitherlocation.

The hardware-in-the-loop simulation configurationsupports (1) functional checks for both flight hardwareand flight software; (2) closed-loop performance; and(3) preparations for aircraft-in-the-loop testing. In thisconfiguration, the simulation interfaces with actualflight hardware or software. The simulation can monitordata output from these elements and provide inputs todrive these flight articles. The controlled environmentprovided by the simulation is often used for failuremodes and effects testing and validation of newhardware before it is installed in the aircraft. In theaircraft-in-the-loop configuration, the simulationinterfaces to the vehicle in a similar manner to supportfull mission, integrated closed-loop testing.

All Dryden simulations use the same basic softwareskeleton (fig 2).2 The aircraft models vary in eachsimulation to reflect the corresponding research vehicle.The basic models include the flight control system,actuator model, aerodynamics model, and enginemodel. In the real-time configurations, the simulationhas routines to interpret inputs from the simulationcockpit or flight hardware. Outputs from the simulationare also sent to drive cockpit instruments and displays,and flight hardware and software. Simulations featurestypically include the ability to produce linear models,automated maneuvers, data recording and use of scripts,as well as many project-specific tools.

Mission Control Center (MCC)

A Mission Control Center (MCC) is composed of acontrol room, and Telemetry and Radar AcquisitionProcessing System (TRAPS) facility with input from


Figure 2. Simulation software structure.

pulse code modulation (PCM), radar, and video streams,as shown in figure 3.

The control room includes numerous flight testengineer and research stations supporting manydifferent functions such as range safety and control,mission control, flight operations, and research. Thecontrol room is configured with overhead videomonitors, communication panels, strip chart recorders,weather and timing displays, and graphics workstations.

Video monitors are used for the display of aircraftdownlink and tracking video. Fixed and mobile camerasystems acquire operational video data for monitoring,control, and safety purposes. Communication panels areavailable at every workstation in the control room,providing voice links between the TRAPS area, thecontrol room, the simulation laboratory, and theresearch aircraft. Graphics workstations are availablethroughout the control room, while strip chart recordersare located at the research stations only.

The TRAPS processes data for the control room andis composed of several front-end computers, a dataserver, and data recorders. The TRAPS performs thedata processing and delivery service for the control

room. The system can process multiple PCM streamssupporting data rates up to 20 Mbits/sec, providing thecapacity of a maximum of 64,000 downlink parametersfor display in the control room. The front-end computersare responsible for data processing of the telemetry andradar streams. This processing includes decommutationof the PCM streams and conversion of PCM data fromtelemetry count values to engineering units. Thefront-end computers are also responsible for parameterderivations, data storage in reflective memory, at-ratedata delivery to the strip charts, and data archiving forpostflight analysis. The Real-time Ethernet Server(RES) gathers the data from the reflective memory anddistributes it to the control room through Ethernet. Theraw PCM and radar data, as well as time-stamps arestored on the data recorders in the TRAPS.

Two types of data are available in the control room:at-rate and RES. At-rate data consists of the downlinkparameters only and is supplied to the strip chartrecorders. The RES provides a current value table(CVT) to the graphics workstations in the control roomfor special purpose displays. The CVT contains allparameters; PCM, radar, system, and derived—at agiven instance in time.


Figure 3. Mission Control Room configuration.

The special purpose displays consist of the GlobalReal-Time Interactive Map (GRIM), Parameter DisplaySoftware (PDS), and Project Application GraphicsExecutable (PAGE). The GRIM application (fig 4)allows range safety personnel the ability to trackmultiple targets anywhere in the world by providing agraphical representation of vehicle position on asimplified map with range information. The PDSapplication (fig 5) is a re-configurable display tool, withfeatures such as alphanumeric displays, light panels, bargraphs, and discrete messages. Where limitations inPDS occur, the PAGE application (fig 6) can be used toprovide custom graphical displays. The page applicationis most commonly used to display vehicle stick, rudder,and control surface positions. Logic can be built intothese displays for fault-error detection, either throughthe derivations in the front-end or through theapplications themselves.

Control Room Training Configurations

Several current projects demonstrate how thesimulation drives the MCC to support control roomtraining, such as the X-43A (Hyper-X) and two F-15(IFCS, XACT) projects. These projects were selected todemonstrate the different configurations for which thesimulation environment can be adapted. For eachproject, this section will outline how the simulationfacility interfaces with the control room and how

information is generated to drive the mission controlroom facilities, simulating day-of-flight operations.

Hyper-X Training Configurations

Control room training is accomplished on theHyper-X project using the simulation in two ways. Thefirst method is to combine training with a ground testthat uses the simulation in the aircraft-in-the-loopconfiguration, shown in Figure 7. The data is typicallytransmitted to the control room through the downlinksystem for data recording and provides an opportunityfor additional control room display checkout. The testcan be conducted from the vehicle location or thecontrol room, allowing engineers the ability to walkthrough various parts of a simulated mission and gaincontrol room familiarization.

The more common configuration used on Hyper-Xhas the real-time simulation residing on a UNIXworkstation installed in the TRAPS facility (fig 8). Adirect connection from the control room to thesimulation lab is not required, since the Hyper-X projectinvolves an autonomous vehicle and no pilot-in-the-loopcapability is needed. All one needs is a simulationcomputer that broadcasts data to whomever wants tolisten, in this case the control room.

The control room displays get their data through anEthernet broadcast from the RES. Since the Hyper-X


Figure 4. F-15 Global Real-Time Interactive Map (GRIM) example.

7

American Institute of Aeronautics and Astronautics

Figure 5. F-15 Parameter Display Software (PDS) example.

Figure 6. F-15 Project Application Graphics Executable (PAGE) example.

8


Figure 7. Hyper-X ground test using the simulation in the aircraft-in-the-loop configuration.

Figure 8. Hyper-X control room training configuration using real-time simulation to simulate flight data and theReal-Time Ethernet Server function.

simulation already includes the ability to mimic RES, itis used as the interface to the control room, drivingeverything downstream of this junction. The softwareused by the control room to compute the derivedparameters is also run in this simulation since many ofthese parameters appear on the displays.

Simulated Real-Time Ethernet Server

The simulated RES function does basically twothings: maps simulation parameters to the CVT, andsends the CVT data to the applications that need it. First,it creates and writes a CVT using the simulation datawith the aid of two input files. The initial file is the CVTitself that is provided by the MCC. Both the simulationand the MCC must use the same CVT file or theparameter mapping will be incorrect. Second is aparameter description file (PDF) that may contain all, orjust a subset of, the CVT parameters. It also contains theassociated simulation parameter name that will be usedto drive that CVT parameter. The parameters in the PDFfile are PCM, radar, system, and derived parameters.Once the simulated RES has built the CVT, the data isbroadcast on Ethernet. The CVT data then becomesavailable to the graphics workstations in the controlroom.

The software that simulates the RES runs as aseparate process, either synchronously orasynchronously with the simulation. This process isstarted by the simulation software and can also bestopped and restarted at any time through the simulationGUI. The user then has the ability to update the inputfiles for the data mapping and restart RES withoutbringing down the entire simulation. For the Hyper-X

project the RES process was synchronized with thesimulation.

Hyper-X Training Objectives and Scenarios

The primary objectives of the control room trainingsessions for the Hyper-X project are to prepare thecontrol room staff for nominal and off-nominalmissions, improve the quality of the flight cards, andoptimize the effectiveness of the control room displays.

Building control room proficiency improves flightsafety and mission success. The opportunities to walkthrough a day-of-flight training scenario are critical forprojects like Hyper-X, where there are few missions andlarge time gaps between flights. These also prove to bebeneficial for personnel who have little to no experiencebeing in the control room to support a flight.

The project also used control room training sessionsto improve the quality of flight cards and emergencyprocedures. These training sessions ensure thatprocedures are in place for all anticipated scenarios andthat they function correctly. Engineers check to see thatprocedures are sequenced properly and serve theirintended purpose. They also check that the control roomdisplays allow them to make their decisions in a correctand timely manner.

For Hyper-X, there were a total of three nominaltraining sessions and three emergency procedurestraining sessions within a five-month period before firstflight. The flight scenario usually begins at or before taxiand continues until the end of the flight experiment orsplashdown. Figure 9 shows the Hyper-X flight profile.During all sessions, the control room is fully staffed


Figure 9. Hyper-X flight profile.

with either primary or back-up personnel. The B-52flight crew is also present on audio communication toperform duties specified by the flight cards.

For each session, engineers have access to allavailable control room displays designed for the project;mechanical strip charts; and the GRIM display showingthe ground track for the B-52, launch vehicle, andresearch vehicle. The simulation provides all datarequired to drive the control room displays during themission, which is usually a subset of the entire downlinkparameter set. For Hyper-X, approximately 25 percentof the CVT data (or close to 1200 parameters) weredriven for the training sessions, either statically ordynamically.

Communication in the control room during the day offlight is also a critical element factored into thesetraining sessions. Various audio communication linesare set up to reflect the day of flight. One line connectsthe test conductor, flight crew, and the mission lead.Another communication line allows all the disciplineleads to communicate with each other. Then a separateline is available to allow members of each discipline totalk amongst themselves. For these training sessions, anisolated line is also set up between the simulationengineer (sitting in the TRAPS area) and the safetyrepresentative (in the control room) who calls to thesimulation engineer to initiate the various scenarios.During emergency procedures training, only these twoindividuals know what the off-nominal scenarios are inorder to maintain the element of surprise for theremaining control room staff.

For off-nominal training scenarios, the simulation caninject a failure on any control room parameter driven bythe simulation, to provide opportunities to exercisego-no-go criteria and emergency procedures. Engineers

who need to make these calls have to rely on the displaypage information to make their decisions correctly andin the time allowed. Thus, the emergency training alsohelps them design the displays to provide them with thedata they need, when they need it. If an abort is called,the simulation can take the project through thatsequence and end the training session. Alternatively, thereactions to the failure are noted, then the simulationreturns to a nominal state and the training proceeds tothe next scenario. Failures may not be modeled exactly,but the first-order effects are included for trainingpurposes.

As in the day of flight, there is a briefing before eachtraining session, but more importantly there is a debriefimmediately afterwards to evaluate the training. In thedebrief, the project reviews the results of the training,the quality of the flight cards, how well peoplecommunicated in the control room, the quality of thecontrol room displays, the setup and stationassignments, and any other issues that came up duringthe training. Feedback from people is also used to helpformulate or improve future training sessions.

Hyper-X Training Data Manipulation

Figure 10 shows data can be manipulated in severalways. The simulation has a feature called “Autotest”that allows the user to force a profile on a desiredparameter. The user can superimpose steps, squarewaves, doublets, ramps, sine waves, or frequencysweeps to create the desired parameter profile. The userspecifies the parameter name, location in the real-timeloop where this profile is injected, and characteristicsabout the profile, such as times, amplitudes, andfrequencies. Up to 512 parameters with four test legsper parameter can be manipulated through this feature.


Figure 10. Simulation data manipulation to drive control room displays.

Another method of manipulation is the Test ManeuverFeature (TMF) that uses an input file containing aspecified time history profile of a desired parameter. Foreach parameter, the user provides a time array and a dataarray and the location in the real-time loop. The user canspecify whether to add this time history profile on top ofthe existing data value produced by the simulationmodels or equations of motion; or replace the valueentirely by the time history profile. Each profile is readin during simulation initialization, and can be turned onor off at any time from a simulation display page andcommand line.

Data produced by both the Autotest and TMF areentirely time-based. In other words, the userpre-determines when a test profile is applied to aparameter, especially on parameters that are producedfrom simulation models and must be overridden toproduce an off-nominal condition. For example, thesquare wave of the Autotest feature was used tointroduce an intermittent failure on certain parametersduring emergency procedure training. Similarly, theTMF was used to generate the ground-track for themission from taxi to launch, overriding the outputs ofthe equations of motion. The data values can also bechanged from the simulation command line to set a newvalue for a desired parameter. This can be done at anytime, as the safety representative makes the call from thecontrol room.

The simulation can imitate a telemetry data loss withthe ability to stop and restart RES from the simulationGUI command line. Though it doesn’t truly depict atelemetry loss that normally results in data being frozenat randomly large numbers, the simulated telemetry lossholds the data at last-value until RES is restarted.

Generally, for all these training sessions, simulationscripts are used to ensure repeatability and easy updatesfor other training sessions. The scripts are just lists ofcommands that the user would normally type from thesimulation command line along with commentstatements. Scripts are run to initialize all theparameters on the control room displays and tointroduce various failure scenarios. Scripts can also benested within others, making it easy to re-use scriptsfrom other sessions if applicable.

Since the simulation has a feature that allows the userto freeze the simulation, the training session can betemporarily halted at any time if a discussion amongstthe control room staff is needed before moving on.When ready, the simulation can resume the test where itwas left off.

F-15 Training Configuration

Unlike the Hyper-X program, the F-15 projectrequires a pilot-in-the-loop, making the simulationlaboratory cockpit an essential part of the control roomtraining configuration. While the F-15 simulation doesuse simulated RES to drive control room displays, itdoes so only when these displays are used in thelaboratory environment. To communicate with theMCC, flight data is instead generated by the simulationas raw PCM, radar, and video streams. The PCM andradar streams are sent to the TRAPS facility throughfiber connections for decommutation and processing,with the resulting data being sent to the control room.The heads-up graphics produced by the simulation arealso sent to the control room to simulate aircraftdownlink or tracking video through a fiber connection.Audio communication is set up to allow the controlroom personnel to talk to the pilot as if on day-of-flight,with a separate communication line for the simulationengineer used in a manner similar to the Hyper-Xprogram. A graphical representation of the configurationis shown in figure 11.

The F-15 configuration is more complex than that ofHyper-X, and it exercises more of the MCC systems,allowing a more complete test of the associatedhardware and software. Additional hardware andsoftware is required in the simulation laboratory tocreate the required data streams, but once these streamsreach the control room they appear exactly as if theywere coming from the aircraft. This configurationallows for a complete end-to-end check of the MCCsystems including all of the TRAPS.

Simulated PCM, Radar, and Video

For the F-15 IFCS and XACT projects control roomtraining, the PCM, radar, and video streams must begenerated in the simulation laboratory using dataproduced by the simulation and PCM processingpackages, as shown in figure 12.

The PCM processing package is composed of twoapplications, the PCM Server and the PCM Formatter.The PCM Server is generated as a separate process fromthe F-15 simulation. The PCM Server determines whichsimulation parameters are required for the PCMstreams, converts the simulation values to telemetrycount values, and stores the resulting values in reflectivememory. The “pcm_process” file is used by the PCMServer to indicate which simulation parameters are to bemapped to which PCM parameters, and contains thenecessary information to convert the engineering units


12


Figure 11. F-15 IFCS and X-ACT control room training configuration using the F-15 simulation.

Figure 12. F-15 methodology for simulating PCM, radar, andvideo data streams for the MCC.

of the simulation values to telemetry count values.3 ThePCM Formatter builds the two required PCM streamsfor the F-15 projects on a system located in a versamodule eurocard (VME) chassis using the telemetrycount values in the reflective memory. The “pcm_vme”file is used by the PCM Formatter to identify whichparameters are needed, where to find them in reflectivememory and how to build the PCM streams. Once thePCM streams are built they are transmitted on fiberconnections, one line for each system, to the MCC.When the PCM streams reach the TRAPS they appearexactly as if they were coming from the aircraft and areprocessed accordingly.

The radar stream is generated in the F-15 simulationbased on positional information that is converted into araw radar format. The raw radar stream leaves the F-15simulation computer on an RS-232 connection that isconverted to fiber and then proceeds to the MCC whereit enters the TRAPS for processing.

The heads-up graphics are used to simulate video forthe control room. A scan converter is required in theF-15 simulation laboratory to transmit the graphics fordisplay in the control room. The video stream is sentover a fiber connection, directly to the control room fordisplay on the overhead video monitors.

F-15 Training Objectives

The objectives of the control room training sessionsfor the F-15 IFCS and XACT projects, like the Hyper-Xproject, are to prepare the control room staff for nominaland off-nominal missions, improve the quality of theflight cards, test various communication protocols, andoptimize the effectiveness of control room displays.

Building control room proficiency contributes greatlyto improving flight safety and mission success. The F-15IFCS and XACT projects used these sessions fortraining primary and backup project personnel. Theproject personnel ranged from new inexperiencedengineers who required more extensive training,experienced engineers who needed refresher training, toengineers covering new responsibilities who requiredmore specialized training. As an additional benefit, newproject pilots were given the chance to interact in thesimulation environment with both primary and backupproject personnel, and at the same time become morefamiliar with the upcoming missions.

As in the Hyper-X project, the control room trainingsessions were used to improve the quality of the flightcards and emergency procedures. Fuel use andcoordination with other aircraft and range activities

require the flight to be efficiently planned out frombefore takeoff to after landing. Executing these missionsin the simulation environment allow personnel toprioritize and rearrange test maneuvers to acquire themaximum amount of useful data within the allowedflights. In emergency situations, there are manyprocedures involved in attempting to regain control ofthe system, such as system resets or activation ofemergency systems. The coordination of activities is ofutmost importance in such a high-stress situation, andthrough practice, personnel can better learn their rolesand responsibilities.

Communication in the control room duringday-of-flight is a critical element factored into thesetraining sessions. During the real mission, too little ortoo much communication can be disastrous. Adding tothe complexity, the F-15 aircraft has two simultaneousexperiments being flown. Since F-15 was training a newtest conductor, multiple communication configurationswere tested in search of one ideal to the missions. In thefinal configuration, three communication paths were setup for the project personnel, with one additional pathused for simulation control information to be sharedamong the people running the session. The first lineincluded the pilot, test conductor, simulated tower andtraffic, and the lead for each of the two experiments. Thesecond line was for the discipline leads to communicatewith each other, as well as with the experiment leads. Athird communication line was set up for internaldiscipline conversations. The line used for simulationcontrol included the simulation engineer, a veteran pilot,the test information engineer, and a safetyrepresentative. The veteran pilot and safetyrepresentative notify the simulation engineer when toinject errors, and the test information engineer andsimulation engineer verify that all the requiredequipment is working correctly.

The control room displays and strip charts show allimportant aircraft and experimental information to thecontrol room personnel. This information gives acomplete view of the aircraft, allowing the engineers tocontrol the flight test and ensure safety. Some of thecritical parameters are not available in the cockpit forthe pilot, requiring the responsible engineer to interpretthe display or strip chart and communicate the results tothe proper people. As an objective of the training, thecontrol room personnel evaluate their displays and stripcharts to verify reception of all required information in aclear, timely manner. Corrections and modifications aremade and then tested, with this cycle repeating untilrequirements are met.


F-15 Training Scenarios

For the F-15 projects, many training sessions wereconducted within a nine-month period before the firstflight. The flight scenario usually begins at or beforetaxi, then continues until landing for the majority ofmissions, or loss of aircraft in extreme emergencysituations. During all sessions, the control room is fullystaffed with either primary or backup personnel, and thesimulation laboratory is staffed with the pilot in thecockpit and a simulation engineer monitoring andcontrolling the required hardware and software. Thehardware and software include the simulated cockpitsystems, related flight hardware, video converter andswitches, and PCM processing equipment, as well as thestandard simulation software and simulation computer.

Before any simulated flight began, a flight brief wasconducted in the same ways as for a real flight. Weatherand range conditions were covered and no-goparameters were reiterated and assigned to theappropriate control room personnel. This is also whenflight cards are given the final review, and any specialresponsibilities are assigned.

During each session, the engineers have access to allavailable control room displays designed for the project,mechanical strip charts, and the GRIM display showing

the ground track of the research vehicle. The simulationprovides all the data required to drive the control roomdisplays during the mission, which is usually a subset ofthe entire downlink parameter set. For the F-15 projects,over 900 parameters were driven for the trainingsessions, either statically or dynamically. The simulatedvideo (fig 13 and 14) is available for display on theoverhead monitors in the control room, with the abilityto simulate the pilot’s view, chase aircraft view, andvarious fixed views.

Unlike the Hyper-X, the F-15 training scenarios werevery dynamic in nature. The first sessions approximateda nominal mission, with the injected errors corrected orworked around and flights continued successfully tocompletion. This was done to allow the control roompersonnel a chance to become accustomed to theenvironment, and evaluate their displays for nominaloperation. The third session began the emergencytraining, where the observing veteran pilot and safetyrepresentative evaluated the rest of the project team. Onthe private communication line, either the veteran pilotor safety representative requested the initiation of anerror. Once an emergency procedure started, the veteranpilot or safety representative could call for more errorsto be injected or allow the procedures to correct theproblem. In one of the later scenarios, the errors wereallowed to compound until ejection of the pilot was


Figure 13. F-15 heads-up out-the-window graphics.

Figure 14. F-15 simulated video.

required, ending the mission. In this way, the team as awhole had a wide range of experiences, from a goodflight to a very high-stress, difficult mission ending withloss of the aircraft.

A debrief was conducted after each training session,covering all the significant portions of the flight. Theveteran pilot and safety representative assessed theperformance of pilot and crew, making suggestions forfuture training. This also gave a chance for the projectpersonnel to suggest changes to displays, procedures,and flight cards.

F-15 Training Data Manipulation

For the F-15 project, there are many failures ofvarying likelihood that could occur, ranging from totaldata loss to a nuisance error on an experiment. In thetraining sessions a set of anomalies are chosenrepresenting some of the more common problems aswell as scenarios requiring in-depth knowledge of theemergency procedures. Some events were thrown in assimple annoyances, for such uncontrollable occurrencescan add to the stress level in the control roomenvironment. The four categories of problems involvethe environment, pilot or communications (or both), theexperiment, and basic aircraft systems.

The environmental problems are simulated usingtower and traffic communications. The safetyrepresentative performed tower communication, and anexperienced person from outside the project simulatedthe traffic communication. Delays were simulated on theground by wind conditions exceeding the no-go limit forthe aircraft and objects on the runway. Once in the air,traffic was noted and adjusted for, and cloud conditionscaused changes in flight plans. On landings, differentrunways were utilized to avoid hazards, or in case ofemergency landings to avoid creating hazards for otheraircraft.

Communication and pilot errors were also injected atinconvenient times in the flights. Simulated loss ofcommunication with the pilot was done by simply notallowing the pilot to talk over the headsets, requiringinteraction with the chase aircraft. Skipping flight cardsand incorrectly performing maneuvers simulated piloterror. There was even a point where the pilot requestedan unauthorized refueling.

Experimental and basic aircraft systems failures weredone both with the simulation software, and by simplyannouncing an error had occurred. From the simulation,flight control failures can be induced on a single channelof a subsystem, multiple channels of a subsystem,complete channel failures for the entire system, or any


combination of the above. This allows for anyassortment of failures for systems, such as air datameasurements, surface controllers, nosewheel steering,gyro sensors, and accelerometers. For each type of error,there is a specific emergency procedure to follow, oftenincluding resetting the system, using alternate systems,or immediate return to base. A random set of these flightcontrol failures were injected during the trainingsessions, both individually and in conjunction withother failures. Simulated engine failures were conductedby simply not allowing the pilot to use the throttles, orannouncing an anomaly, such as that an engine fireoccurred. In the case of the engine fire, the emergencyprocedures were ineffective, forcing the project team toproceed to a pilot ejection.

Concluding Remarks

Good mission preparation is key to both flight safetyand mission success. As demonstrated in the X-43A andF-15 projects, the Dryden simulation is an existingdesign and analysis tool that can also support controlroom training to help achieve these objectives in anefficient, cost-effective manner. The training sessionsnot only prepare the control room staff for the day offlight, but they also allow for improvements in controlroom setup and displays, flight cards, and emergencyprocedures. Also, by taking advantage of existingtechnologies and resources, the training configurationsrequire less cost and time to develop, while greatlyexpanding the capabilities of the Center.

The project manager for F-15 described this ability asan “excellent training opportunity and extremely usefulfor the project team”. For the autonomous X-43Aproject, the project chief engineer found that “throughthese near-realistic practices, we were able to effectively(train) primary personnel and backups, … ended upwith highly effective control room displays, … (and)developed a high level of confidence and preparedness.”

References

1MIL-STD 1553B, Military Standard, AircraftInternal Time Division, Command/Response MultiplexData Bus, Department of Defense, January 1996.

2Norlin, Ken, Flight Simulation Software at NASADryden Flight Research Center, NASA TM-104315,October 1995.

3Fantini, Jay, Conversion From Engineering Units toTelemetry Counts on Dryden Flight Simulators, NASACR-1998-206563, October, 1998.


REPORT DOCUMENTATION PAGE

Form ApprovedOMB No. 0704-0188

Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering andmaintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information,including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington,VA 22202-4302, and to the Office of Management and Budget, Paperwork Reduction Project (0704-0188), Washington, DC 20503.

1. AGENCY USE ONLY (Leave blank) 2. REPORT DATE 3. REPORT TYPE AND DATES COVERED

4. TITLE AND SUBTITLE 5. FUNDING NUMBERS

6. AUTHOR(S)

8. PERFORMING ORGANIZATION REPORT NUMBER

7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES)

9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSORING/MONITORING AGENCY REPORT NUMBER

11. SUPPLEMENTARY NOTES

12a. DISTRIBUTION/AVAILABILITY STATEMENT 12b. DISTRIBUTION CODE

13. ABSTRACT (Maximum 200 words)

14. SUBJECT TERMS 15. NUMBER OF PAGES

16. PRICE CODE

17. SECURITY CLASSIFICATION OF REPORT

18. SECURITY CLASSIFICATION OF THIS PAGE

19. SECURITY CLASSIFICATION OF ABSTRACT

20. LIMITATION OF ABSTRACT

NSN 7540-01-280-5500 Standard Form 298 (Rev. 2-89)

Prescribed by ANSI Std. Z39-18298-102

The Role of Aircraft Simulation in Improving Flight Safety ThroughControl Training

706 51 54 T4 56 00 X43

Karla S. Shy, Jacob J. Hageman, and Jeanette H. Le

NASA Dryden Flight Research CenterP.O. Box 273Edwards, California 93523-0273

H-2501

National Aeronautics and Space AdministrationWashington, DC 20546-0001 NASA/TM-2002-210731

NASA Dryden Flight Research Center uses its six-degrees-of-freedom (6-DOF) fixed-base simulations formission control room training to improve flight safety and operations. This concept is applied to numerous flightprojects such as the F-18 High Alpha Research Vehicle (HARV), the F-15 Intelligent Flight Control System(IFCS), the X-38 Actuator Control Test (XACT), and X-43A (Hyper-X). The Dryden 6-DOF simulations aretypically used through various stages of a project, from design to ground tests. The roles of these simulationshave expanded to support control room training, reinforcing flight safety by building control room staffproficiency. Real-time telemetry, radar, and video data are generated from flight vehicle simulation models.These data are used to drive the control room displays. Nominal static values are used to complete informationwhere appropriate. Audio communication is also an integral part of training sessions. This simulation capabilityis used to train control room personnel and flight crew for nominal missions and emergency situations. Suchtraining sessions are also opportunities to refine flight cards and control room display pages, exercise emergencyprocedures, and practice control room setup for the day of flight. This paper describes this technology as it isused in the X-43A and F-15 IFCS and XACT projects.

Computer programs, flight safety, flight training, integrated mission controlcenter, simulation

29

Unclassified Unclassified Unclassified Unlimited

August 2002 Technical Memorandum

Also presented at the AIAA Modeling and Simlation Technologies conference at Monterey, CA, August 5-8, 2002

Unclassified—UnlimitedSubject Category 05

This report is available at http://www.dfrc.nasa.gov/DTRS/

The Role of Aircraft Simulation in Improving Flight Safety … … · · 2013-06-27The Role of...

Documents

Transcript of The Role of Aircraft Simulation in Improving Flight Safety … … · · 2013-06-27The Role of...