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

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Table 22: Probability levels described in ACJ No. 1 to JAR 25.1309ProbabilitylevelQualitative definition Quantitative description 92Probable 93Remote(category ofimprobable)Extremelyremote(category ofimprobable)Extremelyimprobablemay occur once or several times during thetotal operational life of each aeroplane ofthe same typeunlikely to each aeroplane during its totaloperational life but which may occurseveral times when considering the totaloperational life of a number of aeroplanesof the same typeunlikely to occur when considering thetotal operational life of all aeroplanes ofthe same type, but nevertheless, has tobe considered as being possibleso extremely remote that it does not haveto be considered as possible to occur> 10 -5 per flight hour10 -5 to 10 -7 per flight hour10 -7 to 10 -9 per flight hour< 10 -9 per flight hour2.3.4 United States Advisory Circular 25.1309-1AThe FAA released Advisory Circular 25.1309-1A (System design and analysis) inJune 1988. When it was released, it provided more detailed guidance than the ACJregarding the methods that could be used to satisfy the requirements ofFAR 25.1309. The background section of the document noted that there had been‘an increase in the degree of system complexity and integration, and in the numberof safety critical functions performed by systems’ in the years prior to the AC’srelease. It also stated that due to difficulties in assessing hazards for such systems,more structured approaches were being used for such assessments, which thereforerequired more detailed guidance.Some key features of the AC included the following:• It provided the same guidance as the European ACJ on the concept of an inverserelationship between the severity of the effects of a failure condition and theprobability of its occurrence, and this concept was illustrated with the diagramshown in Figure 33. However, the AC used the term ‘major’ to refer to both the‘hazardous’ and ‘major’ effect levels described in the ACJ, and it occasionallyused the term ‘severe major’ to refer to more serious conditions within thismajor level.• It used the term ‘fail-safe design’, which meant that no single failure shouldresult in a catastrophic failure condition. Although the European ACJ current atthe time did not include this term, the FAA and the European Aviation SafetyAgency (EASA) 94 advised that it was a commonly held principle in both theFAA and the European certifying authorities at the time. 9592939495For example, a value of 10 -3 per flight hour equated to once every 1,000 flight hours, and a valueof 10 -7 per flight hour equated to once per 10,000,000 flight hours.The range for ‘probable’ was also split into two, with ‘frequent’ described as more than 10 -3 perflight hour and ‘reasonably probable’ described as 10 -3 to 10 -5 per flight hour.EASA took over the role of aircraft certification in Europe in 2003.The fail-safe design principle was explicitly stated in later versions of the European ACJ.- 86 -
• It stated that the identification and classification of failure conditions wasnecessarily qualitative. However, the assessment of the associated probabilitylevel could be either qualitative or quantitative, and the analysis could rangewidely in scope depending on factors such as the severity of the failurecondition and the complexity of the system.• It outlined brief guidance on the use of specific analysis techniques. It noted thatfunctional hazard analysis (FHA) was a useful technique to identify and classifypotentially-hazardous failure conditions, and it also referred to other techniquesfor identifying the causes and probabilities of failure conditions, including faulttree analysis and failure mode effects analysis (FMEA).• It noted that the means of compliance described in the AC were not directlyapplicable to software assessments because it was ‘not feasible to assess thenumber or kinds of software errors, if any, that may remain after the completionof system design, development, and test’. The AC stated that design objective(DO) 178A provided an acceptable means of compliance for assessing anddeveloping the software used in computer-based systems.Figure 33: Probability versus consequences graph (from AC25.1309-1A)2.3.5 Design objective 178ADO-178A (Software considerations in airborne systems and equipmentcertification) was produced by the Radio Technical Commission for Aeronautics(RTCA) 96 in March 1985. The purpose of the document was to ‘describe techniquesand methods that may be used for the orderly development and management ofsoftware for airborne digital computer-based equipment and systems’.The design objective outlined three software levels that enabled the developmentprocess to be tailored in accordance with a system’s criticality. The levels referredto the degree of stringency or thoroughness required by the manufacturer’sdevelopment processes to provide design assurance, with Level 1 software requiringthe highest standard.96RTCA is a private, not-for-profit corporation that develops consensus-based recommendationsregarding communications, navigation, surveillance, and air traffic management system issues.- 87 -
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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
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
Page 72 and 73: position 1 on QPA. Further details
Page 74 and 75: class 1 fault messages shown in Tab
Page 76 and 77: 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: The ACJ was built around the princi
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 and 128: According to this model, accidents
Page 129 and 130: 3 FACTUAL INFORMATION: AIR DATA INE
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
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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
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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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