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

Summary of IR data for the occurrence flight (from the FDR)The FDR only recorded two data spikes for the IR parameters, both for magneticheading (at 0441:38 and 0442:04).From 0440:26 to 0440:31, some of the IR parameters showed deviations from theircorrect values. After 0440:31, the IR 1 Fail parameter continuously recorded a failvalue (Figure 20). This result indicated that, after this time, ADIRU 1 flagged all ofits IR 1 data for at least one of its parameters (either pitch attitude or roll attitude) asinvalid, and that the FDR’s source of IR data had quickly switched from IR 1 to IR2 for one or more parameters. From 0443:45, when the crew selected the ATT HDGswitch to CAPT ON 3, the IR 3 became the source of all the IR parameters recordedby the FDR, and no deviations or spikes were recorded.The FDR did not record any fail values for IR 2 or IR 3.1.11.3 Quick access recorder (QAR)System descriptionThe aircraft’s QAR recorded approximately 250 aircraft flight data parameters. 51The data was stored on a removable magneto-optical disk with a capacity of230 megabytes.Files stored on the QAR disk were successfully recovered by the ATSB. Theycontained flight data from the occurrence flight and six previous flights.The QAR and FDR obtained their data via different signal paths (Appendix B).QAR process for recording ADIRU dataThe QAR recorded 16 ADIRU parameters, including the 11 parameters that wererecorded by the FDR (Table 1). As with the FDR, the QAR sampled most of theparameters once per second. However, the FDR and QAR were independentsystems and they sampled the parameters at different times. As with the FDR, bothAOA 1 and AOA 2 were recorded, but only one source of the other parameters wasrecorded.The QAR received its data from a data management unit (DMU), and the source ofthe ADIRU parameters was configurable when the DMU was programmed. For theoccurrence aircraft, the source of most ADIRU parameters was fixed to ADIRU 1.Unlike with the FDR, there was no switching of the source recorded by the QAReven if ADIRU 1 flagged a parameter as being invalid. The only exceptions werecomputed airspeed and magnetic heading; if the QAR data for either of thoseparameters was flagged as invalid by ADIRU 1, then the QAR’s source switched toADIRU 2.51Unlike the CVR and FDR, the QAR was not required to be installed by regulation. However,operators elected to install the recorder to enable routine and easily accessible monitoring ofaircraft and flight crew performance. As the parameters recorded by the QAR were configurableby an operator, it was described as a Digital ACMS Recorder (DAR) in Airbus terminology. Toavoid confusion, the generic term QAR is used in this report. ACMS is an abbreviation forAircraft Condition Monitoring System.- 38 -