What happened
On 29 July 1999, a Boeing 767-336, registration G-BNWN, was parked at Stand D46 at London Heathrow Airport following a public transport flight. After the aircraft had taxied to the stand using the stand guidance system, the engines were shut down and the parking brakes were applied according to standard checklists.
As the boarding jetty was being moved into position to meet the aircraft, a sudden jolt was felt. Shortly after this impact, the dispatcher notified the commander that the jetty had experienced a 'run away' movement. This uncontrolled motion caused the aft corner of the jetty floor to strike the aircraft, resulting in a 9cm score to the fuselage panel located forward of the number one door. There were no injuries to the 11 crew members or 223 passengers on board.
The investigation
The investigation examined the mechanics of the contact between the Europier jetty and the aircraft. It was determined that while the dispatcher had slowed the approach during the final stages of docking, the jetty lurched forward in the final inches of movement.
Technical analysis of the jetty design revealed that the metal plates forming the floor of the bridge are positioned above the top of the rubber protection strip. Consequently, when the protection strip makes contact with the aircraft skin, the pressure can force the rubber downward, allowing the edge of the metal floor plates to strike the fuselage.
Findings
- The primary cause of the damage was the uncontrolled forward movement of the jetty during the final stages of docking.
- The structural design of the jetty's protection strip allowed the metal floor plates to bypass the rubber buffer and contact the aircraft skin upon impact.
Safety action
Following the incident, a modification was implemented on Airbridge D46 to install protective edging on the floor plate. Plans were also established to extend this modification to nine additional Thyssen airbridges.