What happened
On the night of 17 January 2006, a Boeing 777-200, registration OE-LPC, arrived at Singapore Changi Airport Terminal 2 from Melbourne, Australia. As the aircraft was taxiing into parking bay F58, it moved past the designated stop line, resulting in the left-hand engine cowling making contact with an aerobridge. The impact caused a puncture in the engine cowling and damaged the automatic level sensor on the aerobridge. There were no injuries to the crew or ground personnel.
The investigation
The investigation focused on the aircraft's approach speed, the functionality of the Aircraft Docking and Guidance System (ADGS), and the visibility of the ground crew. Investigators found that the pilot flying was accustomed to using a different type of ADGS (Type C) which featured three pairs of amber lights, whereas the system at bay F58 (Type B) only provided one pair. This discrepancy in visual cues contributed to the crew's confusion during the docking process.
Data from the aircraft's flight recorders indicated that the aircraft was not traveling at an excessive speed; the ground speed was approximately 5 knots during the turn and had decelerated to below 1 knot at the time of the collision. While ground personnel believed the aircraft was approaching too fast, the flight recorder data supported the pilot's account of a gradual deceleration.
Furthermore, the investigation examined the ergonomics of the ADGS station. The operator's position was found to be suboptimal, as the console was oriented toward the terminal building, forcing the operator to turn more than 90 degrees to monitor the aircraft. Additionally, the physical placement of the light housing meant the operator could only see half of the light indications from the console.
Findings
- The aircraft was not traveling at an excessive speed during the approach to the bay.
- The pilot relied on the ADGS indications, which were inconsistent with the systems the crew typically used.
- The flight crew lacked access to airport charts that would have identified the specific ADGS types used at different bays in Terminal 2.
- The placement of the ADGS control panel made it difficult for the ground operator to effectively monitor the aircraft's progress.
- The investigation could not replicate the specific light flickering described by the crew, and subsequent system tests showed no mechanical anomalies.
Safety action
Following the incident, the airport operator upgraded the ADGS at all Terminal 2 bays to a laser-based system, similar to the one used in Terminal 1. This new system provides digital countdowns and closing rate information, significantly reducing the manual workload for ground operators.