What happened
On 11 October 2006, a Boeing 767, registration C-GEOU, arrived at London Heathrow Airport from Calgary, Canada. After landing and taxiing to Stand 329, the aircraft was unable to proceed to the stand because a handling agent was not present to activate the stand guidance system. While waiting for the agent, the flight crew completed the shutdown checklist, which included turning off the hydraulic pumps.
During this period, the aircraft began to roll forward slowly. Initially, the crew believed the terminal pier was being moved into position. However, the movement accelerated, and the aircraft travelled approximately 12 feet before the left engine nose cowl struck the pier. The impact caused a dent in the engine cowling. An airport engineer attempted to alert the crew by activating the emergency stop sign, which stopped the aircraft just as the collision occurred. There were no injuries to the 90 passengers or 10 crew members on board.
The investigation
Investigators examined the aircraft's braking systems and the stand's physical characteristics. The investigation established that the commander had attempted to set the parking brake by depressing the toe brakes and pulling up the T-handle on the centre console. However, the pilot failed to maintain pressure on the pedals while releasing the handle, resulting in the brake not being properly engaged.
Further examination of the stand revealed a gradient of 0.42% sloping towards the terminal. While the airfield standards require a maximum slope of 1%, this slight incline contributed to the aircraft's movement once the brake failed to hold.
Findings
- The primary cause of the incident was the pilot's failure to correctly set the parking brake.
- The aircraft was not secured with chocks at the time of the movement.
- The slight gradient of the stand towards the terminal facilitated the forward roll.
- The hydraulic pumps had been turned off as part of the shutdown procedure, which was noted by the co-pilot when low accumulator pressure was observed.