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

For internal aircraft communications, the aircraft had a cabin intercommunicationdata system. Its functions included a passenger address (PA) system for publicannouncements, and a cabin interphone system for communication between theflight and cabin crew stations.No problems were reported with the serviceability of any of the external or internalcommunication systems.1.10 Airport informationLearmonth Airport, which was near Exmouth in Western Australia, was routinelyused by air transport aircraft, and was listed as an ‘alternate’ for internationalflights. 40 The airport had a single, sealed runway (runway 18/36), which was3,047 m long and 45 m wide. Facilities included runway and approach lighting, aprecision approach path indicator, and non-precision navigational aids.1.11 Flight recordersThe aircraft was fitted with three flight recorders: a cockpit voice recorder (CVR), aflight data recorder (FDR), and a quick access recorder (QAR).1.11.1 Cockpit voice recorder (CVR)System descriptionThe aircraft’s CVR recorded the total audio environment in the cockpit area, whichincluded crew conversations, radio transmissions, aural alarms, switch activations,and engine and airflow noise. 41 It retained the last 2 hours of information insolid-state memory, operating on an endless-loop principle.The CVR data was successfully downloaded by the ATSB. Analysis of the audioshowed that power was removed from the CVR soon after the aircraft arrived at theterminal at Learmonth. As a consequence, the CVR retained the recorded audiofrom prior to the initial autopilot disconnection and including both pitch-downevents.Recorded aural alertsThere were no recorded warnings or cautions in the period prior to the autopilotdisconnection alert at 0440:28. The disconnection alert lasted 3 seconds before itwas cancelled by the crew. After that point, there were frequent occurrences of thefollowing aural alerts:• Master caution chimes. The first master caution chime occurred at 0440:33.During the period 0440:28 (autopilot disconnection) to 0442:27 (first4041An alternate is an aerodrome specified in a flight plan to which a flight may proceed when itbecomes inadvisable to land at, or continue toward, the original destination.The aircraft’s CVR was manufactured by L3 Communications (model FA2100; part number2100-1020-02; serial number 000252164).- 32 -