ATSB: Data entry and navigational issues involving Airbus A330 of AirAsia

What happened

On 10 March 2015 Airbus A330, registered 9M-XXM and operated by Malaysian‑based airline AirAsia X, was conducting a regular passenger service from Sydney, New South Wales to Kuala Lumpur, Malaysia. On departure from runway 16R the aircraft was observed by air traffic control to enter the departure flight path of the parallel runway 16L. Following advice from air traffic control, the flight crew identified a problem with the onboard navigation systems. Attempts to troubleshoot and rectify the problem resulted in further degradation of the navigation system, as well as to the aircraft’s flight guidance and flight control systems. The crew elected to discontinue the flight but were unable to return to Sydney as the weather had deteriorated in the Sydney area and the available systems limited the flight to approaches in visual conditions. The aircraft was instead radar vectored to Melbourne, Victoria and the flight completed in visual conditions.

What the ATSB found

The ATSB found that when setting up the aircraft’s flight management and guidance system, the captain inadvertently entered the wrong longitudinal position of the aircraft. This adversely affected the onboard navigation systems however, despite a number of opportunities to identify and correct the error, it was not noticed until after the aircraft became airborne and started tracking in the wrong direction. The ATSB also found that the aircraft was not fitted with an upgraded flight management system that would have prevented the data entry error via either automated initialisation or automatic correction of manual errors.

The flight crew attempted to troubleshoot and rectify the situation while under heavy workload. Combined with limited guidance from the available checklists, this resulted in further errors by the flight crew in the diagnosis and actioning of flight deck switches.

Finally, the ATSB identified that effective monitoring and assistance by air traffic control reduced the risk to the occurrence aircraft and other aircraft in the area.

What's been done as a result

In response to this occurrence the aircraft operator undertook safety action, including:

• the development of a training bulletin and package for its flight crews that emphasised the correct operation and alignment of the air data and inertial reference system
• sharing the lessons learnt from the operator’s internal investigation with all pilots and reviewing the recovery procedures to be undertaken in the form of a flight safety notice.

Safety message

This occurrence highlights that even experienced flight crew are not immune from data entry errors. However, carrying out procedures and incorporating equipment upgrades recommended by aircraft manufacturers will assist in preventing or detecting such errors.

Additionally, the airborne management of this occurrence illustrates the importance of effective communication when dealing with an abnormal situation under high workload conditions. This is especially the case when there is limited guidance available to resolve the issue.

Contributing factors

• When manually entering the coordinates of the aircraft’s position using a data entry technique that was not recommended by the aircraft manufacturer, the longitude was incorrectly entered as 01519.8 east (15° 19.8’ east) instead of 15109.8 east (151° 9.8’ east). This resulted in a positional error in excess of 11,000 km, which adversely affected the aircraft’s navigation systems and some alerting systems.
• The aircraft was not fitted with an upgraded flight management system that would have negated the positional data entry error via either automated initialisation of the air data and inertial reference system, or the automatic correction of manual errors.
• The aircraft’s navigation system probably detected the data entry error and displayed an associated message. However, due to the combination of that message being similar to one displayed during routine alignment of the inertial reference system, and the captain’s understanding that the same alignment-related message may be displayed twice, the error was not identified.
• The first officer did not notice the error in the initialisation coordinates when crosschecking the flight management and guidance system entries after completing the pre-flight external inspection of the aircraft.
• It is likely that data integrity checks detailed in the pre-flight and taxi checklists were either omitted or conducted with the navigation display selected to an inappropriate mode and/or range that concealed the aircraft’s positional error.
• The instrument panels cockpit check was not carried out in accordance with the flight crew operations manual and resulted in the crew not detecting the offset error in the displayed heading.
• Due to the large data entry error remaining undetected, the navigation system did not initialise relative to the aircraft’s actual position prior to take-off. This resulted in an offset error in the displayed heading and a spurious enhanced ground proximity warning system alert shortly after take‑off and again on arrival in Melbourne.
• Activation of the enhanced ground proximity warning system probably distracted the crew and prevented them noticing the turn towards the active parallel runway.

ATSB