Final Report


What happened

On 31 March 2016, an Airbus A330-323, registered 9M-MTB and operated by Malaysia Airlines Berhad (Malaysia Airlines), was being prepared and boarded for a flight from Melbourne Airport, Victoria, to Kuala Lumpur, Malaysia. The captain engaged the aircraft’s park brake before carrying out an external inspection of the aircraft. The resulting lit park brake indicator light on the nose landing gear led the aircraft maintenance engineer to assume that the park brake would remain on. Thinking that the aircraft would remain secure, the maintenance engineer removed the main landing gear chocks out of sequence with the relevant procedure and without informing the others in the ground crew. The ground crews did not check the main gear chocks before removing the nose gear chocks to attach the tow tractor to the nose gear. Unaware that no chocks were in place, and out of sequence with the relevant procedure, the captain released the park brake on return to the flight deck. The aircraft rolled back about 3 m and struck the aerobridge. The aircraft’s forward-left door and hinges, and the aerobridge were damaged. There were no injuries.

What the ATSB found

The ATSB found that the ground and flight crew procedures were not well harmonised, leading to reduced cohesion between the crews, and that the tractor operator’s procedures did not match the way tasks were carried out locally. These problems reduced the likelihood that the respective procedures would be followed correctly. In addition, the flight crew and engineers did not explicitly convey their actions and intentions to the others, resulting in a number of missed opportunities to discover the resulting procedural errors.

What's been done as a result

The engineering company, tractor operator and Malaysia Airlines each planned or initiated safety action in response to this occurrence. The engineering company introduced standard procedures and initiated periodic operational safety inspections at all ports. The tractor operator developed a written procedure to incorporate local differences in work practices and improve coordination. Malaysia Airlines reported that it was planning to amend its procedures so that flight crews advise ground crews whenever the park brake is about to be released. As an interim measure, Malaysia Airlines sent A330 flight crews a reminder to communicate with ground crews before releasing the park brake to verify that chocks are in place.

Safety message

The ATSB stresses the importance of organisations ensuring that ground and flight crew procedures are harmonised to increase the likelihood that potential problems or mistakes are detected before causing harm. It is also important that local variations to procedures are formalised to reduce the risk of the inconsistent completion of tasks, and to improve the organisation’s ability to identify and address potential safety concerns. In addition, the ATSB encourages crews to highlight any procedural problems to their operator in order for them to be reviewed and enhanced as appropriate.

Importantly, when about to perform a key action like removing chocks or releasing the park brake, crews should consider checking with others to identify potential conflicts between tasks. This can reduce the risk of unintentional aircraft movement.

The occurrence

Safety analysis