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

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Researchers have stated that much more research needs to be done to fullyunderstand how expert design engineers conduct their work, and how to effectivelytrain novices to become experts. The research to date in this area has examined arange of design tasks, but limited research has focused on the task of reviewingsystem designs for safety-related problems. In addition, very little research haslooked at the ways that safety analysts conduct activities such as FHA, fault treeanalysis or FMEA.As well as understanding how design engineers and safety analysts conduct theirevaluations of system designs, it is important to understand the factors that canaffect the performance of these personnel. The aviation industry has applied anenormous amount of effort into studying the human factors 121 issues forsafety-critical personnel such as flight crew, air traffic controllers and aircraftmaintenance personnel, and ensuring their work tasks are appropriately designed.However, the investigation found very little research that has examined the humanfactors issues affecting design engineers and safety analysts, or systematicallyexamined the types of factors most likely to lead to design errors.The large amount of human factors research conducted in other domains couldprovide insights into the types of issues that may be relevant for design evaluationtasks. Strigini (1996) noted that research into human performance limitations hasidentified many factors could adversely affect engineering judgements, includingjudgements such as whether a fault tree is complete. For example, research hasshown that human decision-making ability can be affected by a range of differentfactors, such as task complexity, previous experiences, and the availableinformation or cues about the decision or problem (Klein 1998). In addition, systemdesign and evaluation is generally a team activity, with all design decisions beingreviewed by others. Research has shown that detecting errors in other people’sperformance can vary widely depending on the context, and that errors of omissionare relatively difficult to detect (Reason 1990). 122Although general human factors research can be applied to the work of designengineers and safety analysts, it would be more useful if research was specificallyconducted for design evaluation tasks. A key principle of human factors is that thespecific context in which work tasks are conducted needs to be well understood inorder to determine how the design of the tasks, tools, training and guidance materialcan be improved to minimise the likelihood of errors or increase the ability to detectsuch errors.121122Human factors is the scientific discipline concerned with understanding the interactions amonghumans and other elements of a system, and applying theory, principles, data and methods todesign in order to optimise safety, human well-being and overall system performance.Fischoff et al. (1978) and some other researchers (see Silvera 2005) have examined some biasesthat occur with fault tree analysis when information about some failure scenarios is omitted, butnone of this research has been conducted with experienced safety analysts.- 108 -
3 FACTUAL INFORMATION: AIR DATA INERTIALREFERENCE UNITSThe recorded information from the 7 October 2008 flight showed that air datainertial reference unit (ADIRU) 1 (unit 4167) provided some incorrect flight data tothe aircraft’s other systems. This included data spikes on air data reference (ADR)parameters that were not flagged as invalid by the ADIRU. Several systemsdetected problems with ADIRU 1’s performance, but the unit itself did not recordany faults, and extensive testing of the unit did not identify any relevant problems.The same failure mode has occurred on two other occasions.Given that the reasons for the failure were not identified by unit testing or recordedfault messages, a more detailed examination of the ADIRU design, recorded data,and in-service performance was conducted.3.1 LTN-101 ADIRU history3.1.1 Equipment specificationDuring the development of the A330/A340 aircraft, the aircraft manufacturerdeveloped equipment specification SPE A 3410 A002 for the air data and inertialreference system (ADIRS). The version applicable to the LTN-101 ADIRU designwas issued in February 1990.The specification outlined the technical requirements that the air data inertialreference system (ADIRS) and its major components (including the ADIRUs)needed to satisfy. These included requirements for the ADIRU’s functions,operating conditions, data formats, performance levels, interface design, andgeneral characteristics. It also outlined general safety objectives, general reliabilityobjectives, built-in test equipment (BITE) requirements, safety analysisrequirements, and a software criticality level. Where applicable, the specificationreferred to regulatory requirements, industry standards and Airbus directives.The integration of the ADIRS with other systems was the responsibility of theaircraft manufacturer. Consequently, the ADIRS equipment specification did notstate how the data transmitted from the ADIRUs would be used by other aircraftsystems.3.1.2 Overview of LTN-101 usageThe LTN-101 ADIRU was initially designed to meet the Airbus equipmentspecification for use on A330/A340 aircraft, and it was certified in 1993. In additionto being used on A330/A340 aircraft, it was also certified for use on the AirbusA320, the Saab 2000, and the Bombardier CRJ, Q400 and CL604 models.The LTN-101 was one of two ADIRU models certified for the A330/A340. By theend of 2008, LTN-101 ADIRUs were fitted to about 44% of the A330/A340 fleet.As of April 2010, LTN-101 units had accrued over 128 million hours of operation,including 113 million hours in Airbus aircraft. Over 8,000 units had beenmanufactured by July 2010, and the units were used by over 60 different operators.- 109 -
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ATSB TRANSPORT SAFETY REPORTAviatio
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Published by: Australian Transport
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3 FACTUAL INFORMATION: AIR DATA INE
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DOCUMENT RETRIEVAL INFORMATIONRepor
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TERMINOLOGY USED IN THIS REPORTOccu
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CSMCSSCVRDADSDCDGACDMCDMUEASAECAMED
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RAMRTCASATCOMSAESAOSDSECSEESEUSSASS
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FCPC design limitationAOA is a crit
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- xviii -
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associated with a master caution ch
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Figure 2: Aircraft track and key ev
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The crew decided that they needed t
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1.3 Damage to aircraftThere was sig
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• The flight crew provided inputs
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exceeding a predefined safe flight
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Table 1: Examples of ADIRU flight d
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Inertial reference partThe IR part
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ADIRS switching controlsIn normal o
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Processing by ADIRUs and FCPCsEach
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The information presented on the fl
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A system could flag its output data
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Table 4: Summary of indications for
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Figure 17: ECAM engine / warning di
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Table 6: Required actions associate
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For internal aircraft communication
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Table 7: Sequence of events (from t
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In summary, the source of most of t
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Summary of IR data for the occurren
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Figure 22: QAR plot showing oscilla
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QAR dataOverall, the QAR recorded 4
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Flight crew pitch inputsDuring manu
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They provided information for maint
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Table 11: Cockpit effect messages d
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Table 13: Troubleshooting data rela
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position 1 on QPA. Further details
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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
Page 80 and 81: did not identify any faults. The BI
Page 82 and 83: Comparison of the three occurrences
Page 84 and 85: 1.17.2 Processes for reporting and
Page 87 and 88: 2 FACTUAL INFORMATION: ELECTRICAL F
Page 89 and 90: monitored external systems that pro
Page 91 and 92: Each FCPC used a number of paramete
Page 93 and 94: AOA computation logicThe FCPC softw
Page 95 and 96: Figure 29: FCPC processing of sever
Page 97 and 98: Table 19: Characteristics of elevat
Page 99 and 100: Simulation of AOA values for the fi
Page 101 and 102: 2.2.2 Review of recorded flight con
Page 103 and 104: second PRIM 3 FAULT. The role of ma
Page 105 and 106: The ACJ was built around the princi
Page 107 and 108: • It stated that the identificati
Page 109 and 110: The second part of the V-cycle invo
Page 111 and 112: • Functional requirements. These
Page 113 and 114: 2.4.5 Safety assessment activitiesG
Page 115 and 116: equipment software and aircraft ins
Page 117 and 118: 2.5.4 Factors associated with the i
Page 119 and 120: it is very difficult if not impossi
Page 121 and 122: applicable to highly-integrated or
Page 123 and 124: Ongoing developmentsA range of rese
Page 125 and 126: To conduct an effective fault tree
Page 127: According to this model, accidents
Page 131 and 132: • inertial reference input/output
Page 133 and 134: 3.3 Examination of data-spike patte
Page 135 and 136: Figure 38: ARINC 429 word for an AO
Page 137 and 138: 3.3.4 Data-spike patterns for the 7
Page 139 and 140: Figure 43: Qualitative correlation
Page 141 and 142: etween the values of any of the fou
Page 143 and 144: 3.4.3 Calculating parameter valuesA
Page 145 and 146: 3.4.5 Packaging the ARINC 429 wordT
Page 147 and 148: 3.4.8 Transmitting data to other sy
Page 149 and 150: ARINC 429 packaging analysisThe ADI
Page 151 and 152: component configurations of differe
Page 153 and 154: manufacturer reported such BITE dat
Page 155 and 156: 3.6 Potential trigger types3.6.1 Ba
Page 157 and 158: such as liquids or small loose frag
Page 159 and 160: wires). The electric 144 field stre
Page 161 and 162: Although the investigation could no
Page 163 and 164: 3.6.6 Single event effectsBackgroun
Page 165 and 166: until a few years ago, were not dir
Page 167 and 168: Unit testingIn 2005, as part of the
Page 169 and 170: that involved a NAV IR and/or NAV A
Page 171 and 172: EMI from other aircraft systems (su
Page 173 and 174: from ADIRU 1 was not correctly reco
Page 175 and 176: • Detected failure. Any failure w
Page 177 and 178: 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
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place. Although aviation manufactur
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equiring cabin crew to enforce the
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With the information available to t
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ADIRU 1 affected the operation of a
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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
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APPENDIX B: FLIGHT RECORDER INFORMA
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APPENDIX C: POST-FLIGHT REPORTThe f
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APPENDIX D: OTHER DATA-SPIKE OCCURR
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Occurrence on 27 December 2008Overv
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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
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Visual inspectionsExternal visual i
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(ADR) output databuses. Loading on
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Unit 4167 passed 2,223 of 2,272 tes
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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
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• crew actions: the passenger’s
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The questionnaire respondents were
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was centred across the passenger’
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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
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APPENDIX N: SOURCES AND SUBMISSIONS
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Hanson, RJ 1987, Conducted electrom
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Tvaryanas, AP 2003, ‘Epidemiology
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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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