What happened
On 23 February 2013, an Airbus A319-131, registration G-EUOA, was taxiing to Stand 503 at London Heathrow Airport following a commercial flight from Basel. The aircraft was carrying 103 passengers and 6 crew members. As the aircraft approached its parking position using the electronic guidance system, its left wingtip collided with a mobile steps vehicle that had been parked in the inter-stand clearance area.
The collision caused the mobile steps to topple onto their side, protruding into the stand safety area. The impact resulted in a broken left navigation light cover and a dent to the underside of the left wing adjacent to the winglet. The ground equipment vehicle also sustained damage. Following the impact, the Turn Round Manager signaled an emergency stop, which the flight crew executed. The aircraft then taxied forward to its designated parking spot without further incident.
The investigation
The investigation established that the mobile steps vehicle had been positioned in the inter-stand area near the north end of Terminal 5, with its front protruding into the main building area. While the flight crew had performed a visual check and believed the stand was clear, the commander noted that the specific clearance margins for wingtips at these stands were not fully understood by the crew.
A technical examination of the steps vehicle revealed a defect in the parking brake operating lever. This defect prevented the brakes from being fully applied. It was determined that engine vibration and the orientation of the vehicle likely caused the vehicle to move forward into the aircraft's path after it had been parked.
Findings
- The primary cause of the collision was the unintended movement of the mobile steps vehicle into the aircraft's path.
- A defective parking brake lever on the steps vehicle meant the brakes were not fully engaged.
- The vehicle was parked in a prohibited inter-stand clearway, protruding approximately 18 inches into the stand safety area.
- The vehicle was too large to be parked in that location without infringing on sterile stand areas.
- The flight crew's assessment that the stand was clear was inaccurate due to the vehicle's position.