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

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Potential effects during different phases of flightThe two flight envelope mechanisms would not issue pitch-down commands whenthe aircraft was close to the ground. More specifically:• The high AOA protection had a confirmation time of 2 seconds when theaircraft was below 500 ft above ground level. As AOA spikes longer than1 second would result in the relevant ADR being rejected, this protection couldnot be activated by a multiple AOA spike scenario that occurred below 500 ft.• The anti pitch-up compensation was only available above Mach 0.65 and in theclean configuration. Therefore, this mechanism would not realistically occurduring final approach or initial climb situations, when the aircraft was operatingin close proximity to the ground.Following the 7 October 2008 occurrence, the aircraft manufacturer conductedflight simulations with the aircraft just above 500 ft and at typical approach speeds.Based on the high AOA protection command alone, 83 the decrease in altitude due toa pitch-down without a flight crew response was not significant (less than 100 ft).When the flight crew were asked to respond to the pitch-down, the decrease inaltitude was much less. During these simulated events, there was an autopilotdisconnection, but the flight crew easily recovered control.2.2 Examination of FCPC performance on 7 October 20082.2.1 Simulations to determine role and origin of elevator deflectionsThe aircraft manufacturer conducted a series of simulations to determine the natureof the factors that could have contributed to the pitch-downs on the 7 October 2008flight. These activities were performed using an engineering simulation tooldeveloped during the aircraft development process (see section 2.4.4).Effect of elevator deflectionsThe first simulation study used the elevator deflections recorded on the FDR andthe flight conditions present at the time of the first pitch-down to confirm theaircraft’s pitch movements during the event. The study found that the recordedelevator deflections were sufficient to explain the aircraft movement, whichconfirmed that turbulence did not contribute to the pitch-downs.Role of sidestick inputsThe second study used the flight crew’s sidestick pitch inputs that were recorded onthe FDR as inputs into the engineering simulation tool. It confirmed that thesidestick inputs were not sufficient to explain the recorded elevator deflections atthe start of the pitch-downs, and therefore another factor was involved in initiatingthese deflections.83Anti pitch-up compensation was not included as it would not realistically be available at thataltitude.- 78 -
Simulation of AOA values for the first pitch-downThe third study determined if values of AOA FCPC input could lead to the recordedelevator deflections for the first pitch-down (at 0442:27), after taking account of thesidestick pitch inputs. The simulations used a two-spike scenario with the followingproperties:• the first AOA 1 spike triggered a 1.2-second memorisation period with the valueof AOA FCPC input being 2.3° (based on the recorded AOA 1 and AOA 2 valuesbefore the spike)• the second AOA 1 spike was present at the end of the memorisation period,leading to a step-change of AOA FCPC input to 26° (based on an average of anAOA 1 spike of 50.6° and an AOA 2 value of 2.3°)• a steady decrease in the 26° AOA FCPC input value after the spike stopped (due tothe rate limiting function).The time period that the second spike existed after the end of the memorisationperiod was then varied. This time period is represented by the value of ‘X’ inFigure 30.Figure 30: AOA values used in the simulation study for first pitch-down 84This study confirmed that the recorded elevator deflections during the first pitchdowncould be produced using a 26° value of AOA FCPC input for a duration of about400 msec at the end of the memorisation period (that is, the value of X was 400msec). Based on this simulation, it could be concluded that the AOA 1 spike of50.6° lasted at least 400 msec but less than 1 second. 858485Scenario D in Figure 29 illustrates how AOA 1 spikes could produce these AOA FCPC input values.If the duration of the spike was greater than 1 second, then the ADR 1 would have been rejectedfor the remainder of the flight (and a relevant fault message recorded).- 79 -
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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
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
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: Table 19: Characteristics of elevat
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 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
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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
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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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