What happened
On 10 March 2015, an Airbus A330-343X, registered 9M-XXM, was preparing for a scheduled passenger flight from Sydney to Kuala Lumpur. During the pre-flight cockpit preparations, the captain manually entered the aircraft's position coordinates into the flight management system by copying them from a sign outside the cockpit window.
Shortly after takeoff from runway 1 and 16R, the aircraft's enhanced ground proximity warning system issued a terrain alert. While the crew determined no actual terrain conflict existed, the aircraft began a gradual left turn that deviated from the assigned departure route. Air traffic control observed the aircraft entering the flight path of the parallel runway 16L, which at that moment was occupied by another aircraft waiting for departure. The crew, facing degrading navigation and flight guidance systems, were unable to return to Sydney due to deteriorating weather and instead diverted to Melbourne to complete the flight under visual conditions.
The investigation
The investigation focused on the sequence of events leading to the navigational deviation and the subsequent system degradation. Investigators examined the manual initialization of the air data and inertial reference system (ADIRS) and the specific data entered into the multipurpose and control display unit (MCDU). The inquiry also reviewed the crew's attempts to troubleshoot the malfunctioning systems and the impact of high workload on their decision-making.
Findings
- The primary cause of the deviation was a manual data entry error where the captain incorrectly entered the aircraft's longitude during the initial setup.
- The aircraft lacked an upgraded flight management system capable of automated initialization or error correction that could have flagged the incorrect coordinates.
- The flight crew's efforts to resolve the technical issues under high workload led to further errors in managing flight deck switches.
- The degradation of the navigation, flight guidance, and flight control systems was a direct result of the troubleshooting attempts.
- Effective monitoring and intervention by air traffic control prevented a collision with the aircraft on the parallel runway.
Safety action
Following the incident, the aircraft operator implemented several safety measures, including:
- The creation of a specialized training package for flight crews regarding the correct alignment and operation of the air data and inertial reference system.
- The distribution of a flight safety notice to all pilots, sharing lessons learned and reviewing recovery procedures.