Aircraft and Crew Information
The incident involved two commercial air transport passenger aircraft: an Airbus A340-313 (registration 6Y-JMP) and a Boeing 777-222 (registration N781UA). The A340, manufactured in 1992, was powered by four CFM56-5C turbofan engines. Data on the A340 crew were not recorded. The B777, manufactured in 1996, was equipped with two Pratt & Whitney PW4000 turbofan engines. Its commander, aged 47, held an Air Transport Pilot's Licence and had accumulated 20,000 flying hours, including 806 hours on type. The B777 crew reported no injuries.
History of the Flight
On 14 July 2004, at 1254 UTC, in daylight with fine weather and good visibility, the A340 was cleared to taxi from Stand 314 at Terminal Three to holding point LOKKI for a departure from Runway 27L at London Heathrow Airport. The B777, which had pushed back from Stand 321 (also at Terminal Three), was cleared to follow the A340 for the same runway. While taxiing, both crews were instructed to monitor the Heathrow ATC Tower frequency.
After holding at LOKKI, the A340 was directed by the Air Departures Controller to line up and wait on Runway 27L behind an Airbus A310 that was holding at N2E. The A340 taxied forward and stopped on the right side of the holding area behind an Airbus A320, well short of the N2W traffic bar. The B777 was then instructed to taxi forward and hold on the left. As the B777 taxied behind the A340, its commander (the handling pilot) used cockpit reference points, as advised in the company's operations manual, to ensure clearance between the B777's right wing tip and the A340's tail. The crew considered the A340 closer than typical at other airports, but the co-pilot noted this was not unusual for Heathrow, which has less space.
After clearing the A340's tail, the B777 followed the taxiway centreline to the left side of the holding area. During this turn, the B777's right wing tip contacted the A340's left winglet. The A340 commander felt a jolt and informed ATC; cabin crew initially believed the tail was struck. The B777 crew did not notice the contact. Airport staff dispatched a ground vehicle and subsequently reported damage to both aircraft wingtips and debris on the ground. Line-up clearances were cancelled, and both aircraft returned to stands for inspection. The holding area was closed for debris clearance.
Damage and Engineering Examination
Examination revealed that the A340's left winglet sustained localized deformation on the trailing edge, approximately 30% span from the tip. The B777's right wing tip fairing exhibited bruising and paint smearing extending from the leading edge to the trailing edge, along with a fractured navigation light lens and damage to other light fittings. The damage pattern indicated that the B777's right wing tip struck the A340's left winglet from behind as the B777 passed. Overlap was minimal (about 300 mm), and damage was confined to removable wingtips. The Minimum Equipment List for each aircraft permits flight with winglets or wingtip fairings removed.
Recorded Data and Analysis
The A340's Cockpit Voice Recorder (CVR) and Flight Data Recorder (FDR) were not retrieved; the B777's CVR and FDR were downloaded by the AAIB. The B777's 30-minute CVR had overwritten incident data because power was not isolated in time. The FDR provided useful information. ATC radio transmissions and ground radar recordings were also used. The ground radar, recorded with a multilateration system overlay, showed aircraft movements. The radar plots, each separated by 1 second, covered the collision time. The collision occurred at 12:53:51 hrs. The FDR recorded a lateral acceleration spike of 0.04g to the right at a speed of 6 kt, with magnetic heading samples of 115°M and 118.5°M around the impact.
The operator's procedures for CVR preservation after an incident are outlined in the Flight Operations Manual. Authorization to remove a specific tape may only be given by senior flight operations management. The CVR circuit breaker on the B777 is located in the electronics bay under the floor, with no cockpit access for the crew to stop recording.
ATC Procedures
The Manual of Air Traffic Services states that aircraft movements on the manoeuvring area are subject to permission from aerodrome control. The Air Departures Controller aimed to maximize runway usage by alternating blocks of heavy and medium aircraft, filling the holding area. For Runway 27L, specific taxiing procedures stipulate that aircraft follow a single yellow centreline that splits into two parallel lines for side-by-side holding. The collision occurred when the B777 had not yet reached the section of the line parallel to the A340's position.