Incident
At 18:50 local time on 25 July 1999, an Airbus A310 and a Boeing 737-500 collided at Frankfurt/Main Airport. The A310 was taxiing on taxiway ALFA toward the holding point KILO for runway 07L. The Boeing 737 was holding in taxiway JULIETT, awaiting the departure of a Boeing 747 from runway 07L before proceeding to the holding point. The left wing of the A310 contacted the right horizontal stabilizer of the Boeing, causing components to be torn off or deformed on both aircraft. Neither crew reported any injuries. Both aircraft sustained heavy damage.
Investigation
The German Federal Bureau of Aircraft Accident Investigation (BFU) was notified at 19:20 by airport air traffic control. Investigators secured the flight data recorders from both aircraft and collected written statements from the crews. Cockpit voice recorders were not available as they had continued recording and overwritten the relevant information. Interviews with both pilots and the air traffic controller were conducted.
Findings
The Boeing 737 had been instructed to "taxi into JULIETT, hold short of the runway." The crew stated they stopped the aircraft between the CAT I holding point marking and the CAT II/III marking, intending to move to the holding point after the Boeing 747 started its takeoff. Damage analysis and a photograph taken by an airport vehicle driver confirmed that the Boeing's nose gear was precisely on the CAT II/III marking. This placed the aircraft 51 m short of the holding point marking, causing its tail to protrude into taxiway ALFA.
The A310 crew reported that they had noticed the Boeing when entering taxiway ALFA but assumed that obstacle clearance was assured because the aircraft was in a position assigned by air traffic control. At the time of the collision, the A310 crew was occupied with evaluating a takeoff offer from the tower for departure from KILO. They did not perceive the impact and continued taxiing until directed to park after the Boeing crew reported the collision.
The tower controller, responsible for multiple aircraft and vehicles, observed the Boeing from his control tower position approximately 700 m away. He saw the aircraft from the side and estimated it was angled 20–30° relative to taxiway JULIETT but did not detect its exact longitudinal position or that it extended into taxiway ALFA. The controller was engaged in radio communication with the A310 regarding a takeoff clearance and simultaneously monitoring ten other landing, landing, and taxiing aircraft. The investigation noted that the controller's workload likely delayed his awareness of the Boeing's unusual position.
Flight data recorder analysis showed the collision occurred at 18:49:47. At that time, the Boeing was heading 191° and the A310 was heading 251°. No taxi speed was recorded for the A310. The collision was not evident from the A310's recorded parameters.