What happened
On 10 January 2003, a Boeing 777-269ER, registration 9K-AOA, was taxiing to Stand M 32 at London (Heathrow) Airport for a public transport operation. As the aircraft approached its assigned parking spot, the pilot observed the Aircraft Positioning and Information System (APIS) countdown change abruptly from 1.2 metres to a "T FAR - STOP" warning. This indicated that the aircraft had exceeded its intended stopping point. The crew halted the aircraft immediately and shut down both engines, allowing the 232 passengers and 15 crew members to disembark without injury.
Upon inspection, it was discovered that the leading edge of the number 1 engine cowling had struck the airbridge, resulting in a puncture. The impact also caused buckling to the airbridge floor and damage to its auto leveller. Additionally, the airbridge wheels were found to be positioned one metre outside their designated operating circle.
The investigation
The investigation examined the functionality of the APIS and the movements of the aircraft and airbridge. The pilot's account noted the sudden change in distance indications. However, the aircraft dispatcher, who monitored the arrival, stated that the airbridge wheels were within the correct markings prior to the collision and that the APIS countdown appeared normal until the stop command was issued. An engineer present at the stop position also observed the "STOP" indication and moved clear as the nosewheel continued past the intended mark. The aircraft eventually came to rest four metres beyond the designated position.
Analysis of the APIS data logs revealed no system faults during the arrival manoeuvre. The records confirmed that the guidance system functioned as intended, providing the correct stopping information and the stop instruction. A subsequent repositioning of the aircraft using a tug also showed the APIS operating normally, with the stop command occurring at the correct location.