Incident Overview
On 25 February 1998, a Boeing 747-436, registration G-BNLA, arrived at London Gatwick Airport after an uneventful scheduled passenger flight from Harare, Zimbabwe. During the subsequent post-flight engineering inspection, damage was discovered on both the right inboard and right outboard elevators. The flight crew had not previously been aware of the damage.
Inspection and Search
No debris was found on the parking stand at Gatwick, and the aircraft had not passed close to any other aircraft, vehicle, or structure while taxiing in. A search of the route from the runway to the stand yielded nothing.
Pre-Departure Events at Harare
The commander reported that prior to departure, the aircraft had been parked on a north easterly heading on Stand 7 at Harare International Airport. It was dark at the time, and no elevator damage was noted during the crew's pre-flight inspection. During the engine start-up sequence, an inbound Airbus A340 taxied in a south westerly direction past the right side of the Boeing 747, then turned right through 90° and stopped close behind it, apparently under the direction of an airport marshaller. The A340 remained in this position until the Boeing 747 taxied away before being parked on the same stand. The commander indicated that the A340 crew made an RTF request for the Boeing to use minimum breakaway thrust when starting to taxi, as their aircraft was in close proximity behind the Boeing 747.
Flight Handling Observations
The first officer, who was the handling pilot, commented that he felt an unexpected slight yaw during the take-off rotation. However, analysis of the Quick Access Recorder (QAR) data did not show any significant yaw, lateral acceleration, or elevator control surface position split during the take-off sequence.
Damage Examination
Detailed examination showed that a narrow object, painted blue, had struck the underside of the right hand outboard elevator, causing damage to the lower skin. It travelled inboard, causing more serious damage to the inboard elevator, and broke out a piece of honeycomb structure about two feet long and up to 10 inches wide from the trailing edge. The object stopped before striking the tailcone.
Investigation at Harare
Checks with the airport authority and ATC at Harare indicated no records of any abnormal events or retrieval of debris from the ramp area. However, the Boeing 747 operator's local representative located a small piece of fibreglass-type debris from the ramp area. This was forwarded for examination but proved too small to be positively confirmed as debris from the Boeing 747 elevator structure.
An examination of ground equipment and vehicles at Harare found that all such equipment was white in colour. Of the vehicles in use, only one was painted blue, and it was undamaged.
Possible Contact with Airbus A340
Calculations showed that, for the laden weight of the Boeing 747, the A340 winglet would have been close to the height required to strike the Boeing 747's elevators. However, no damage was reported to have occurred to the right winglet of the A340 aircraft, so it could not be positively concluded that it had been in contact with the Boeing 747 elevators.