What happened
On 14 July 2004, during daylight operations at London Heathrow Airport, two large aircraft were involved in a ground collision. An Airbus A340-313, registration 6Y-JNP, was stationary in the Runway 27L holding area, positioned behind an Airbus A320. At the same time, a Boeing 777-222, registration N781UA, was instructed by ground controllers to taxi forward and hold on the left side of the same holding area.
As the Boeing 777-222 proceeded along the taxiway, the flight crew utilized cockpit reference points to maintain clearance from the tail of the stationary 6Y-JMP. However, as the aircraft transitioned toward the left side of the holding area, the right wingtip of the N781UA made contact with the left winglet of the 6Y-JMP. The impact caused localized deformation to the A340's winglet and damage to the 777's wingtip fairing, including a fractured navigation light lens. There were no injuries to the crew or passengers involved.
The investigation
The AAIB investigation examined the aircraft damage, ground radar plots, and flight data recorder (FDR) from the N781UA. The analysis confirmed that the collision occurred at a low taxi speed of approximately 7 knots. The investigation also reviewed the Air Traffic Control (ATC) instructions provided to both crews.
Investigators noted that the flight crew of the N7 and 777 believed the proximity of the A340 was typical for the constrained space at Heathrow. Furthermore, the investigation looked into the preservation of Cockpit Voice Recorder (CVR) data, noting that the 30-minute recording on the N781UA had been overwritten because the crew followed company procedures that required seeking high-level authorization before isolating the recorder's power.
Findings
- The collision was caused by the desire of ATC to maximize aircraft capacity within the holding area to prevent taxiway congestion.
- The Boeing 777-222 crew's reliance on cockpit reference points may have increased their confidence in maneuvering through tight spaces, potentially leading to the contact.
- The physical constraints of the Heathrow holding area made wingtip clearance difficult to guarantee.
- The existing company procedures for the N781UA operator regarding the preservation of CVR data were found to be inadequate for ensuring data availability following a serious incident.