What happened
On January 23, 2016, a Boeing 777-300 landed at Warsaw Chopin Airport (EPWA) for a scheduled refueling stop. Due to technical constraints and the presence of passengers on board, refueling was required to be performed exclusively from the left side of the aircraft. Consequently, a ground service crew positioned mobile stairs on the right side of the aircraft.
Following the completion of the refueling process, the operator of the mobile stairs verified that the aircraft doors were closed, retracted the stabilizer feet, and began to slowly reverse the vehicle. During this maneuver, the operator felt a sudden jolt and stopped the vehicle to investigate. Upon inspection, it was discovered that the canopy (the soft upper section) of the stairs had become caught on the open aircraft door.
Upon repositioning the stairs to the door, maintenance technicians inspected the aircraft and found that the upper edge of the door frame had been bent over a length of approximately 70 centimeters. Following consultation with the airline's operations center, the decision was made to cancel the flight.
The investigation
The investigation focused on the ground handling procedures and the equipment involved. Testing of the mobile stairs operator immediately following the incident showed no evidence of alcohol consumption, and the individual held all necessary qualifications for the task. The mobile stairs themselves were found to be in good working order and were subject to regular manufacturer-mandable inspections.
An analysis of the existing operating procedures and instructions for the mobile stairs did not reveal any flaws that could have contributed to the incident. Furthermore, two separate on-site inspections confirmed that the stairs' canopy cannot damage the aircraft door if the door is properly closed.
Findings
- The primary cause of the damage was that the aircraft door was left open while the operator was lowering the stabilizer feet of the mobile stairs.
- The physical contact between the stairs' canopy and the door frame occurred during the reversing maneuver.