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

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The fields had the following functions:• Label. An eight-bit field that uniquely identified the parameter. As the label wastransmitted first, other systems could ignore the parameters they did not require.• Source/destination identifier. A two-bit field that identified either the source ofthe transmission or the intended destination.• Data. A 19-bit field that contained the output parameter’s value.– Some of the output parameters did not use all of the 19 bits as they were notnecessary for the required range and resolution. For example, AOA used 13of the 19 bits (see Figure 38 for an example). Any unused bits were set to ‘0’.– Each data bit represented a value that was double that of the preceding bit,and all values were summed to produce the actual parameter value.– Some of the parameters also used one of the bits as a sign bit, indicatingwhether the value was positive or negative.• Sign/status matrix (SSM). A two-bit field used to indicate the status (or validity)information of the transmitted word. The available values had the followingmeanings: failure warning, no computed data, functional test, and normaloperation (section 1.6.8).• Parity. A single bit that enabled a receiving system to check the integrity of adata word’s transmission. The bit was set to ‘1’ if the rest of the ARINC 429data word contained an even number of ‘1’s, or was set to ‘0’ otherwise. Theword was only accepted by the receiving system if it had an odd number of ‘1’s.The ARINC 429 word was constructed or packaged within the CPU module.However, the parity bit was calculated and added by either the air data input/outputmodule or the inertial reference input/output module (depending on the databusover which the word would be eventually transmitted).3.3.3 Recording system data formatAlthough the ADIRU outputted data using a 32-bit word with 19 bits available forthe parameter value, the FDR (and QAR) used 12-bit words for the parameter value.When extra resolution was required, the FDR used two words. For example, altitudewas split into a ‘coarse’ word (with 12 bits of data) and a ‘fine’ word (with 10 bitsof data, one sign bit and one unused bit). Other FDR parameters did not require12 bits; for example, AOA was recorded using nine bits (eight data bits and onesign bit), and Mach was recorded using eight bits (eight data bits and no sign bit).The FDR recorded different ARINC 429 data bits for each parameter. For example,the FDR recorded altitude data bits 14 to 27 and the sign bit (29), AOA data bits 20to 27 and the sign bit, and Mach data bits 19 to 26.- 114 -
Figure 38: ARINC 429 word for an AOA value of 50.625°The value of each data bit also varied for each parameter. For example, a ‘1’ fordata bit 27 meant 45° for AOA and 32,768 ft for altitude. Figure 39 and Figure 40show how the data fields for AOA, Mach, and altitude represented real values in theARINC 429 format. These figures also show the range of data bits used for eachparameter in the ARINC 429 format, and as recorded on the FDR. Thered-highlighted figures are discussed in the following sections.- 115 -
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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
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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
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 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: 3.3 Examination of data-spike patte
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
Page 179 and 180: the aircraft and ADIRU manufacturer
Page 181 and 182: 4 FACTUAL INFORMATION: CABIN SAFETY
Page 183 and 184: 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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