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On 11 January 2007, at about 0718 Eastern Daylight-saving Time, an Airbus A320 aircraft, registered ZK-OJB, departed runway 34L at Sydney Airport, NSW for Auckland, New Zealand and was assigned a radar heading by Air Traffic Control (ATC). The controller noticed that the aircraft turned onto an incorrect heading and informed the flight crew. The crew checked the aircraft's compasses and found that they were reading approximately 40 degrees incorrectly and that a GPS PRIMARY LOST message had appeared on the aircraft's multi-purpose control and display unit and navigational display. The crew advised ATC that they had navigational difficulties and elected to return to Sydney for landing.

When the aircraft returned to the departure gate, the flight crew noticed that the inertial reference system (IRS) had been aligned to the incorrect longitude. The operator's investigation into the incident found that the IRS had been aligned by maintenance staff prior to the crew boarding the aircraft. The incorrect alignment of the IRS was not noticed during a number of subsequent checks prior to departure.

As a result of this incident, the operator has proposed to develop a training program for all company pilots designed to improve discussion and guidance in relation to threat and error management issues.

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