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

Figure 2: Aircraft track and key eventsAfter returning the aircraft to FL370, the flight crew commenced actions to dealwith multiple ECAM caution messages. These were:• NAV IR 1 FAULT: the required action presented on the ECAM was to switchthe ATT HDG (attitude heading) switch from the NORM position to the CAPTON 3 position. The crew completed the required action and cleared the message.• F/CTL PRIM 3 FAULT 13 : the required action was to select the flight controlprimary computer 3 (FCPC 3) OFF and then select it back ON. The crewcompleted the required action and cleared the message.• NAV IR 1 FAULT: this message had reappeared at the top of the ECAM withno additional required actions, and was cancelled by the crew.• F/CTL PRIM 1 PITCH FAULT: there was no required action associated withthis message. The crew confirmed that there was no associated fault light on theoverhead panel and then started reviewing the flight control page on theECAM’s system display.1.1.4 Second in-flight upset (0445:08)At 0445:08 (1245:08 local time), while the crew were responding to the ECAMmessages, the aircraft commenced a second pitch-down movement, reaching amaximum pitch angle of about 3.5° nose down. The flight crew described the eventas being similar in nature to the first event but less severe. The captain promptlyapplied back pressure on his sidestick to arrest the pitch-down movement. He saidthat, consistent with the first event, this action initially had no effect, but soon afterthe aircraft responded normally. FDR data showed that the flight control system didnot respond to flight crew inputs for at least 2 seconds, and that the aircraftdescended 400 ft over 15 seconds before returning to FL370.13F/CTL is used for fault messages associated with the flight control system. PRIM is the term usedin fault messages and operational procedures to refer to a flight control primary computer (FCPC).- 4 -