What happened
On 15 February 2007, two aircraft were taxiing toward Runway 24R at Manchester Airport for scheduled passenger services. The first aircraft, a Boeing 777-240(LR), registration AP-BGY, was cleared by Ground Movement Control to taxi along Taxiway Juliet to Holding Position J1. The second aircraft, a DHC-8-402 Dash 8, registration G-JEDR, was stationary at Holding Position JA1.
As the Boeing 7 and 777 approached the position of the stationary Dash 8, the commander elected to deviate slightly to the left of the taxiway centerline to increase separation. During this maneuver, the right wingtip of AP-BGY struck the rudder of G-JEDR. The crew of the Boeing 777 did not immediately realize a collision had occurred, though they felt a slight motion. The crew of the DHC-8 felt a physical bump through the rudder pedals and identified the impact.
The investigation
The investigation examined flight data recorder (FDR) and cockpit voice recorder (CVR) data from both aircraft. Analysis of the FDR showed that as the Boeing 777 approached the Dash 8, it began to decelerate and turn left. Computer-generated mapping of the taxiway geometry indicated that if the DHC-8 had been stopped precisely on the holding line, the clearance between the aircraft would have been sufficient to avoid contact. However, the data suggested the DHC-8 had stopped several meters short of the marking.
Engineers examined the damage, finding that the impact had bent the trailing edge of the G-JHD rudder over a length of approximately 80 cm, necessitating its replacement. The Boeing 777 sustained only minor superficial scratches to its wingtip.
Findings
- The primary cause of the collision was that the DHC-8-402 Dash 8 had stopped short of the holding position marking.
- The commander of the Boeing 777 deviated from the taxiway centerline, which reduced the available margin of safety.
- The air traffic control instructions provided to the Boeing 777 crew did not clearly communicate a specific collision risk, as the controllers believed the clearance was adequate.
- The visibility of the aircraft's wingtips from the flight deck is limited, and the crew's ability to monitor clearance was hindered by the aircraft's position relative to the centerline.