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

The recorded data showed that the failure mode started at 0828:52. In terms of theADR data, the crew selected ADR 1 OFF 28 seconds after the failure mode started(at 0829:20). Consequently, ADR 1 ceased transmitting data and the FDR switchedits source for the ADR parameters, except angle of attack (AOA) 1 and AOA 2,from ADR 1 to ADR 3. 205 When the crew switched the source of ADR parametersfor the captain’s displays to ADR 3 (0831:25), the FDR’s source of AOA 1 alsoswitched to ADR 3. During the brief period that ADR 1 data was recorded:• There were no spikes in AOA 206 or Mach.• There were two spikes for altitude, and two spikes for static air temperature.There were also four small changes (10 kts) in computed airspeed.ADIRU 1 flagged all of these anomalies as valid data.In terms of the IR data:• Although the crew reported switching IR 1 off, the QAR data showed that theIR 1 parameters continued to be transmitted by the ADIRU until after landing.• From the start of the event until after the aircraft landed, the QAR recordednumerous spikes in pitch attitude, drift angle, body lateral acceleration, inertialvertical speed, and magnetic heading. 207• In addition to the data spikes, all of the IR parameters showed persistentdeviations from their expected values. For most of these parameters, thedeviations showed oscillatory behaviour. The groundspeed parameter increasedto 1,000 kts, where it remained for the rest of the flight, except for a number oflower-value data spikes.• With only brief exceptions, ADIRU 1 flagged all of the IR 1 data after the startof the event (0828:52) as invalid.There were no stall warnings recorded (consistent with no spikes on the captain’sAOA) and no overspeed warnings recorded (consistent with only small changes oncomputed airspeed). However, there were repetitive master cautions recorded afterthe failure mode commenced, consistent with the occurrence of ECAM messages.205206207At this time the QAR stopped recording any ADR parameters from ADIRU 1. Computed airspeedwas defined as a switchable parameter, and its source switched to ADIRU 2 at this time.Some oscillations were observed in the recorded data for AOA 1 after the ADR Fail parametercommenced indicating Fail. These oscillations were examined and matched the no computed datacycling behaviour expected when ADR 1 was no longer outputting data, consistent with it beingswitched off (Appendix B).As with the 7 October 2008 occurrence, the FDR only recorded a small number of spikes at thebeginning of the event. For most of the IR parameters, the FDR switched its source if the ADIRUflagged its data as invalid. However, the QAR always sourced its data from ADIRU 1.- 240 -