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Investigation report; Malaysian Airlines Reg 9M-MTB
Investigation report on Malaysia Airlines, Airbus A330-323 registered 9M-MTB that hit the Airbridge at Melbourne airport on 31 March 2016.
What happened
The aircraft had been parked in the bay for several hours following its previous flight, and was secured using wheel chocks under the left main and nose landing gears.
The aircraft captain engaged the park brake before disembarking to perform a pre-flight external inspection of the aircraft.
Shortly after the captain checked the main landing gear chocks, the AME removed them from the left main landing gear in preparation for pushback.
The AME was aware that this step was not in accordance with the normal sequence for pushback with a towbarless tractor, but thought that the aircraft would be secure because the:
- nose landing gear chocks were installed
park brake indicator light on the nose landing gear had been on.
Subsequently as the tractor driver moved towbarless tractor towards the nose landing gear, the aircraft began to move very slowly backwards and stopped after coming into contact with the aerobridge, having rolled backwards about 3 m in 22 seconds.
Hearing the noise and realising that the aircraft had moved, the LAME radioed the flight crew to set the park brake.
The aircraft’s forward-left door and the aerobridge were damaged.
Separately, the aircraft captain was unaware that the docking process was underway and that no chocks were in place. Although the flight crew procedures stated that the park brake should only be released when the wheel brakes were hot (generally only shortly after landing), or after the aircraft doors were closed and with ground crew clearance, the captain released the park brake on return to the flight deck. In the absence of any braking mechanism, the aircraft commenced moving until it struck the aerobridge.
Contributing factors
• The aircraft maintenance engineer removed the main landing gear chocks before the towbarless tractor was secured to the aircraft and out of sequence with the normal operating procedures.
• Consistent with local practices, neither the engineers nor the tractor driver checked that the main landing gear chocks were in place before attempting to dock the towbarless tractor to the aircraft.
• The aircraft captain released the park brake out of sequence with the normal operating procedures.
