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

pitch-down) there were at least 22 master caution chimes. 42 The chimescontinued for the remainder of the flight.• Stall warnings. The first stall warning occurred at 0440:45, and there were atleast 10 stall warnings in the 2-minute period between the autopilotdisconnection and the first pitch-down. The warnings continued for theremainder of the flight. In all cases the stall warnings were brief; on someoccasions they were truncated before the first ‘STALL’ was annunciated, and inall cases they were truncated before a full cycle of the warning (that is, ‘STALLSTALL’ followed by a cricket noise).• Continuous repetitive chimes. This type of alert was used for several differenttypes of warnings (that is, level 3 failures). Based on a comparison with the FDRdata and other information sources, the only warning conditions present on theflight, other than the autopilot disconnection and the stall warnings, wereoverspeed warnings (also discussed in section 3.3.4). The first aural overspeedwarning occurred at 0440:37, and there were at least seven warnings in the2-minute period between the autopilot disconnection and the first pitch-down.The warnings continued for the remainder of the flight, but they were lessfrequent than the caution chimes and stall warnings. In all cases the aural signalswere brief and they were truncated after two or less chimes.1.11.2 Flight data recorder (FDR)System descriptionThe aircraft’s FDR recorded approximately 1,100 parameters of aircraft flightdata. 43 It used solid-state memory as the recording medium and operated on anendless-loop principle.The FDR data was successfully downloaded by the ATSB, and it included data forover 217 hours of aircraft operation, comprising the occurrence flight and24 previous flights.Overview of FDR dataThe FDR data showed that the flight was uneventful until 0440:26, when anomaliesin the recorded data for the ADIRU 1 parameters commenced. The first recordedanomaly was a deviation in the pitch attitude. At 0440:28 the autopilot disengagedand data spikes 44 became evident on all of the recorded ADIRU 1 parameters.Table 7 provides a summary of the key events recorded on the FDR. Further detailson ADIRU-related data are provided in the rest of this section. Further informationrelating to AOA data is provided in section 1.11.4, and further information aboutthe pitch-down events is provided in section 1.11.5.424344Not all of the master caution chimes would have resulted in a new message on the ECAM(section 1.6.11).The aircraft’s FDR was manufactured by L3 Communications (model FA2100; part number2100-4043-02; serial number 000428627).A spike is a short-duration change in the value of a parameter that exceeds (or is below) thenormal value by a large amount.- 33 -