The Australian Transport Safety Bureau was advised on 27 December 2008 of an occurrence that day involving a Qantas Airbus A330-300 aircraft while in cruise at FL360 (36,000 ft) enroute from Perth to Singapore.

At about 0829 UTC (1729 Local Time), the autopilot disconnected and the crew received an ECAM message (NAV IR 1 Fault) indicating a problem with ADIRU Number 1. The crew actioned the Airbus Operations Engineering Bulletin (OEB) procedure by selecting the IR 1 push-button to OFF and the ADR 1 push-button to OFF. Both OFF lights illuminated. The crew elected to return to Perth and an uneventful overweight landing was conducted. At the time that the autopilot disconnected, the aircraft was approximately 260 nautical miles (NM) North-West of Perth airport and approximately 350 NM South of Learmonth airport.

It is very early in the investigation and too soon to draw any conclusions as to specific causal factors involved in this incident. As it appears to be a similar event to a previous event involving an A330 aircraft (AO-2008-070 on 7 Oct 2008) it will be included as part of the earlier investigation. The ATSB investigation will explore all aspects of the operation of the aircraft, including examination of recorded data, and any commonalities with past occurrences.

While the investigation is likely to take a number of months, the ATSB has been working with a number of national and international parties on this investigation and plans to release an Interim Factual report by about mid-February 2009.

Should any critical safety issues emerge that require urgent attention, the ATSB will immediately bring such issues to the attention of the relevant authorities who are best placed to take prompt action to address those issues.

ADIRU = Air Data Inertial Reference Unit
ECAM = Electronic Centralized Aircraft Monitor
IR = Inertial Reference
ADR = Air Data Reference
NAV = Navigation

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Last update 01 April 2011