What happened
On August 21, 2008, at approximately 06:22 local time, an Airbus A340-313 operating a scheduled flight from Tehran to Frankfurt/Main (EDDF) was involved in a ground collision. After landing on runway 25L, the aircraft taxied via taxiway G toward parking stand B26.
As the flight crew maneuvered the aircraft into the stand, the co-pilot observed a passenger bus on the adjacent service road. While the crew initially believed the bus was maintaining a safe distance, a "Follow-me" vehicle suddenly approached the aircraft from the front, prompting the captain to perform an abrupt braking maneuver. Shortly after the aircraft came to a halt, the crew realized that the number 4 engine had struck the passenger bus. The collision caused light damage to the aircraft's engine cowling and the upper front section of the bus. There were no injuries among the 224 passengers or the 12 crew members.
The investigation
The BFU investigation examined the movements of the aircraft, the bus, and the service vehicles, as well as the airport's taxiway markings and signaling systems. The investigation reviewed cockpit voice recorder (CVR) and digital flight data recorder (DFDR) data, along with statements from the flight crew, the bus driver, and the Follow-me driver.
Investigators looked into the functionality of the AGNIS/PAPA visual docking system and the specific traffic rules regarding the two different stop lines marked on the service road. The investigation also assessed the visibility of the aircraft from the perspective of the bus driver and the effectiveness of the airport's traffic separation measures.
Findings
- The primary cause of the collision was the insufficient separation distance between the passenger bus and the taxiway of the Airbus A340-313.
- The driver of the passenger bus failed to stop at the first designated stop line, which was intended to keep vehicles clear when aircraft are taxiing toward stand B26.
- The spatial configuration of the service road and taxiway G created a high-risk situation, as the aircraft's path and the vehicle's path intersected.
- From the position of the first stop line, the taxiway G was not fully visible to vehicles traveling from the east, meaning the bus driver did not perceive the approaching aircraft until it was too late to avoid the collision.
- The decision-making process for vehicle drivers—choosing between the first and second stop lines based on the aircraft's destination—placed undue responsibility on individual drivers in heavy traffic.
- The AGNIS/PAPA docking system was not active at the time of the incident, and the visual guidance provided by the system was not relied upon by the crew for clearance.