In-flight upset - 154 km west of Learmonth, WA, 7 October 2008,

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RAMRTCASATCOMSAESAOSDSECSEESEUSSASSMTATTHSTSDUTCVHFVLFRandom access memoryRadio Technical Commission for AeronauticsSATellite COMmunicationsSociety of Automotive EngineersSpécification assistée par ordinateur (computer assistedspecification)System displayCommon name for flight control secondary computer (FCSC)Single event effectsSingle event upsetSystem safety assessmentSign/status matrixTotal air temperatureTrimmable horizontal stabiliserTroubleshooting dataUniversal Time CoordinatedVery high frequencyVery low frequency- xiv -
EXECUTIVE SUMMARYKey investigation outcomesThe in-flight upset on 7 October 2008 occurred due to the combination of a designlimitation in the flight control primary computer (FCPC) software of the AirbusA330/A340, and a failure mode affecting one of the aircraft’s three air data inertialreference units (ADIRUs). The design limitation meant that, in a very rare andspecific situation, multiple spikes in angle of attack (AOA) data from one of theADIRUs could result in the FCPCs commanding the aircraft to pitch down.When the aircraft manufacturer became aware of the problem, it issued flight crewprocedures to manage any future occurrence of the same ADIRU failure mode. Theaircraft manufacturer subsequently reviewed and improved its FCPC algorithms forprocessing AOA and other ADIRU parameters. As a result of this redesign,passengers, crew and operators can be confident that the same type of accident willnot reoccur.The investigation identified several lessons or reminders for the manufacturers ofcomplex, safety-critical systems. With the knowledge that systems are becomingincreasingly complex, it also identified a need for more research into how designengineers and safety analysts evaluate system designs, and how their tasks, tools,training and guidance materials could be improved to minimise design errors.Although in-flight upsets are very rare events, the accident on 7 October 2008 alsoprovided a salient reminder to all passengers and crew of the importance of wearingtheir seat belts during a flight whenever they are seated.Summary of the occurrenceAt 0132 Universal Time Coordinated (0932 local time) on 7 October 2008, anAirbus A330-303 aircraft, registered VH-QPA and operated as Qantas flight 72,departed Singapore on a scheduled passenger transport service to Perth, WesternAustralia. At 0440:26, while the aircraft was in cruise at 37,000 ft, ADIRU 1started providing intermittent, incorrect values (spikes) on all flight parameters toother aircraft systems. Soon after, the autopilot disconnected and the crew startedreceiving numerous warning and caution messages (most of them spurious). Theother two ADIRUs performed normally during the flight.At 0442:27, the aircraft suddenly pitched nose down. The FCPCs commanded thepitch-down in response to AOA data spikes from ADIRU 1. Although thepitch-down command lasted less than 2 seconds, the resulting forces were sufficientfor almost all the unrestrained occupants to be thrown to the aircraft’s ceiling. Atleast 110 of the 303 passengers and nine of the 12 crew members were injured; 12of the occupants were seriously injured and another 39 received hospital medicaltreatment. The FCPCs commanded a second, less severe pitch-down at 0445:08.The flight crew’s responses to the emergency were timely and appropriate. Due tothe serious injuries and their assessment that there was potential for furtherpitch-downs, the crew diverted the flight to Learmonth, Western Australia anddeclared a MAYDAY to air traffic control. The aircraft landed as soon asoperationally practicable at 0532, and medical assistance was provided to theinjured occupants soon after.- xv -
Page 1: ATSB TRANSPORT SAFETY REPORTAviatio
Page 4 and 5: Published by: Australian Transport
Page 6 and 7: 3 FACTUAL INFORMATION: AIR DATA INE
Page 9 and 10: DOCUMENT RETRIEVAL INFORMATIONRepor
Page 11: TERMINOLOGY USED IN THIS REPORTOccu
Page 14 and 15: CSMCSSCVRDADSDCDGACDMCDMUEASAECAMED
Page 18 and 19: FCPC design limitationAOA is a crit
Page 20 and 21: - xviii -
Page 22 and 23: associated with a master caution ch
Page 24 and 25: Figure 2: Aircraft track and key ev
Page 26 and 27: The crew decided that they needed t
Page 28 and 29: 1.3 Damage to aircraftThere was sig
Page 30 and 31: • The flight crew provided inputs
Page 32 and 33: exceeding a predefined safe flight
Page 34 and 35: Table 1: Examples of ADIRU flight d
Page 36 and 37: Inertial reference partThe IR part
Page 38 and 39: ADIRS switching controlsIn normal o
Page 40 and 41: Processing by ADIRUs and FCPCsEach
Page 42 and 43: The information presented on the fl
Page 44 and 45: A system could flag its output data
Page 46 and 47: Table 4: Summary of indications for
Page 48 and 49: Figure 17: ECAM engine / warning di
Page 50 and 51: Table 6: Required actions associate
Page 52 and 53: For internal aircraft communication
Page 54 and 55: Table 7: Sequence of events (from t
Page 56 and 57: In summary, the source of most of t
Page 58 and 59: Summary of IR data for the occurren
Page 60 and 61: Figure 22: QAR plot showing oscilla
Page 62 and 63: QAR dataOverall, the QAR recorded 4
Page 64 and 65: Flight crew pitch inputsDuring manu
Page 66 and 67:
They provided information for maint
Page 68 and 69:
Table 11: Cockpit effect messages d
Page 70 and 71:
Table 13: Troubleshooting data rela
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position 1 on QPA. Further details
Page 74 and 75:
class 1 fault messages shown in Tab
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If there was a discrepancy between
Page 78 and 79:
1.15 Survival aspectsInformation on
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did not identify any faults. The BI
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Comparison of the three occurrences
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1.17.2 Processes for reporting and
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2 FACTUAL INFORMATION: ELECTRICAL F
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monitored external systems that pro
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Each FCPC used a number of paramete
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AOA computation logicThe FCPC softw
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Figure 29: FCPC processing of sever
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Table 19: Characteristics of elevat
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Simulation of AOA values for the fi
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2.2.2 Review of recorded flight con
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second PRIM 3 FAULT. The role of ma
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The ACJ was built around the princi
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• It stated that the identificati
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The second part of the V-cycle invo
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• Functional requirements. These
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2.4.5 Safety assessment activitiesG
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equipment software and aircraft ins
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2.5.4 Factors associated with the i
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it is very difficult if not impossi
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applicable to highly-integrated or
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Ongoing developmentsA range of rese
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To conduct an effective fault tree
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According to this model, accidents
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3 FACTUAL INFORMATION: AIR DATA INE
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• inertial reference input/output
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3.3 Examination of data-spike patte
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Figure 38: ARINC 429 word for an AO
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3.3.4 Data-spike patterns for the 7
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Figure 43: Qualitative correlation
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etween the values of any of the fou
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3.4.3 Calculating parameter valuesA
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3.4.5 Packaging the ARINC 429 wordT
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3.4.8 Transmitting data to other sy
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ARINC 429 packaging analysisThe ADI
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component configurations of differe
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manufacturer reported such BITE dat
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3.6 Potential trigger types3.6.1 Ba
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such as liquids or small loose frag
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wires). The electric 144 field stre
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Although the investigation could no
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3.6.6 Single event effectsBackgroun
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until a few years ago, were not dir
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Unit testingIn 2005, as part of the
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that involved a NAV IR and/or NAV A
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EMI from other aircraft systems (su
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from ADIRU 1 was not correctly reco
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• Detected failure. Any failure w
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The ADIRU manufacturer’s analysis
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the aircraft and ADIRU manufacturer
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4 FACTUAL INFORMATION: CABIN SAFETY
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Summary details of the cabin crew
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section, and the ninth flight atten
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Table 29: Significant cabin communi
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Figure 48: Example of damage to the
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4.3.2 Seat belt examinationsSix pas
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The flight crew’s procedures requ
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takeoff, landing or when the seat-b
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Table 31: Levels of injuryInjury le
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4.6.4 Injuries to seated occupants
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The percentage of occupants who wer
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Statistical analyses 197 were done
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passengers reported that they had h
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that seat belts should be worn only
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4.8.2 Handholds in the cabinThe FAA
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Figure 53: Overview of the 7 Octobe
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process needs to ensure that there
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and determine whether they could le
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useful in this case. If the EFCS sp
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5.3.2 Risk associated with the fail
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• All three events occurred in a
Page 224 and 225:
place. Although aviation manufactur
Page 226 and 227:
equiring cabin crew to enforce the
Page 228 and 229:
With the information available to t
Page 230 and 231:
ADIRU 1 affected the operation of a
Page 233 and 234:
6 FINDINGSFrom the evidence availab
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• As of April 2010, the LTN-101 a
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did not illuminate. The new OEB (A3
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modifications were made to its guid
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this advice. At the time of the fir
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APPENDIX A: VERTICAL ACCELERATIONST
Page 247 and 248:
APPENDIX B: FLIGHT RECORDER INFORMA
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APPENDIX C: POST-FLIGHT REPORTThe f
Page 251 and 252:
- 231 -
Page 253 and 254:
- 233 -
Page 255 and 256:
APPENDIX D: OTHER DATA-SPIKE OCCURR
Page 257 and 258:
Occurrence on 27 December 2008Overv
Page 259 and 260:
Figure D2: FDR data for the 27 Dece
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ADIRU informationADIRU 1 was the sa
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APPENDIX E: ADIRU TESTINGTest plan
Page 265 and 266:
Visual inspectionsExternal visual i
Page 267 and 268:
(ADR) output databuses. Loading on
Page 269 and 270:
Unit 4167 passed 2,223 of 2,272 tes
Page 271 and 272:
dwells (sustained testing at a fixe
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APPENDIX F: AIRCRAFT LEVEL TESTINGI
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APPENDIX G: ELECTROMAGNETIC RADIATI
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cannot be ‘decoded’ by the rece
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APPENDIX H: SINGLE EVENT EFFECTSNot
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Factors affecting SEE exposureAn ai
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portions of memory are constantly b
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Depending on the form of EDAC, sing
Page 288 and 289:
• crew actions: the passenger’s
Page 290 and 291:
The questionnaire respondents were
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was centred across the passenger’
Page 294 and 295:
Previous occurrencesThe seat belt m
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Australian turbulence eventsThe mos
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APPENDIX L: SEAT BELT USE IN ROAD V
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Table L1: Recent seat belt use rate
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US Federal Aviation AdministrationT
Page 307 and 308:
APPENDIX N: SOURCES AND SUBMISSIONS
Page 309 and 310:
Hanson, RJ 1987, Conducted electrom
Page 311 and 312:
Tvaryanas, AP 2003, ‘Epidemiology
Page 313:
In-flight upset - 154 km west of Le
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In-flight upset - 154 km west of Learmonth, WA, 7 October 2008,

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