What happened
On 11 December 2006, a Syrian Arab Airlines Boeing 747 SP, registration YK-AHB, landed at Stockholm/Arlanda airport after a scheduled flight from Damascus. During the final stages of taxiing toward gate 18 in darkness, the aircraft collided with the airbridge structure. The top of the left wing struck the underside of the airbridge housing, resulting in a large hole in the aircraft's wing and damage to the airbridge itself. There were no injuries among the 116 people on board.
As the aircraft approached the gate, the ground-based docking system provided guidance via an LED display. The operator at the airbridge housing, attempting to program the correct aircraft version, had entered the data for a standard B 747 rather than the shorter SP version. Because the system's laser scanning technology at this specific gate could not distinguish between the different lengths of the 747 variants, the aircraft continued to taxi based on the incorrect profile. The collision occurred just as the emergency stop button was activated by ground staff and the operator.
The investigation
The Swedish Accident Investigation Authority (SHK) examined the docking system, the training protocols of the handling company, and the airport's information systems. The investigation found that the gate operator had received an IATA code, "74L," which she did not recognize. Lacking a conversion table or specific training regarding aircraft variants, she relied on advice from colleagues and entered a standard B 747 profile.
Investigators also noted that the airport's central data system and the airbridge's independent docking database were not integrated, leading to conflicting nomenclature. Furthermore, the investigation revealed that the laser scanning system at the gate was an older version that lacked the capability to detect the difference in fuselage length between the standard 747 and the SP model.
Findings
- The primary cause was an inadequate training program and insufficient safety guidance for gate operators regarding the docking system.
- The operator was unable to correctly identify the aircraft version due to unfamiliarity with IATA codes and the absence of a conversion reference.
- The docking system's software allowed the operator to override the pre-selected SP setting with a standard 747 setting.
- The laser scanning equipment at the gate was unable to differentiate between the two aircraft models.
- Previous safety recommendations regarding these specific docking vulnerabilities had not been fully implemented at the gate involved.
Safety action
SHK issued several recommendations to the Swedish Civil Aviation Authority to improve safety at Arlanda airport, including:
- Updating the training curriculum for gate operators to include proficiency in various aircraft versions.
- Implementing a safety and quality control system for airbridge and docking guidance operations.
- Upgrading all relevant gates at Arlanda with modern docking systems capable of distinguishing between different aircraft versions.
- Redesigning docking terminals to prevent the misinterpretation of aircraft type information.