What happened
On 26 June 2006, an Airbus A320-232, registration G-EUUF, was involved in a ground collision at London Heathrow Airport. Following a routine pushback from Stand 139, the aircraft was cleared to taxi via Taxiway Kilo. During the pushback process, a technical fault occurred with the towbarless tractor, preventing the driver from immediately moving the vehicle to a safe distance.
As the flight crew completed their after-start checklists and began taxiing under their own power, the headset operator provided the 'all clear' signal. However, the tractor had not yet been repositioned away from the aircraft's path. The aircraft's right engine struck the rear of the tractor, causing significant damage to the engine's underside, including the inlet cowl, fan cowl, and thrust reverser structure. The impact also damaged the tractor's chassis leg. Following the collision, smoke was observed from the engine jetpipe, prompting the crew to shut down the engine and apply the fire handle as a precaution.
The investigation
Investigators examined the aircraft, the tractor, and the flight recorders. The reconstruction revealed that the co-pilot's view of the tractor was likely obscured by the cockpit window pillar due to his forward-leaning posture during the scan. The investigation also focused on the tractor's mechanical state, discovering a defect in the proximity sensors. The 'cradle up' sensor was triggering the 'cradle down' indicator, which inhibited the drive system and required the use of an override button. This defect prevented the driver from quickly clearing the taxiway.
Findings
- The primary causal factor was the headset operator providing the 'all clear' signal before the tractor was at a safe distance from the aircraft.
- The co-pilot failed to visually identify the tractor during the starboard scan.
- A mechanical defect in the tractor prevented it from being driven away immediately once the aircraft began to move.
- There was a lack of effective supervisory presence on the ramp to enforce adherence to established pushback and towing procedures.