What happened
On November 30, 2010, at Amsterdam Airport Schiphol, a Boeing 747-400, registration PH-BFB, was undergoing de-icing procedures on the J-platform. Following the completion of the de-icing process, the de-icing supervisor signaled an "all clear" to the flight crew and authorized them to contact ground control for taxi instructions.
As the aircraft began to taxi, the front section of its left horizontal stabilizer made contact with the extended boom of a de-icing vehicle. The impact caused the vehicle to tilt, resulting in the operator's cabin falling approximately ten meters onto the platform. The collision caused heavy damage to the aircraft's stabilizer and the de-icing vehicle, and the de-icing operator was seriously injured.
The investigation
The investigation examined the sequence of events on the J-platform, the communication protocols between the crew and ground staff, and the training of the personnel involved. The inquiry focused on why the aircraft was cleared to move while de-icing operations were still active at the rear of the plane.
Investigators looked into the supervisor's recent transition into the role, the functionality of the radio equipment, and the specific instructions provided by the PAD controller regarding operational efficiency. The investigation also reviewed the visibility of the tail section from the cockpit of a large aircraft like the Boeing 747-400.
Findings
- The primary cause of the accident was that the aircraft began taxiing while a de-icing vehicle was still positioned near the left stabilizer.
- The supervisor issued an "all clear" signal prematurely, having lost situational awareness and overlooking the vehicles still working on the tail section.
- The supervisor had not yet fully mastered the operational tasks and was experiencing high workload due to pressure to increase efficiency.
- Communication interference and equipment malfunctions contributed to increased stress and difficulty in monitoring the entire process.
- The supervisor was relatively new to the position and had not received sufficient on-the-job training or practical guidance for this specific platform.
- The flight crew's role was limited, as the vehicles at the stabilizer were not visible from the cockpit during the initial taxi movement, and they were no longer monitoring the supervisor's specific frequency.
Safety action
While the OVV did not issue new recommendations because the existing recommendations from KLM's internal analysis were deemed sufficient, the investigation highlighted the need for better guidance and customized training for new employees, particularly those without an aviation background. The report also noted that the current process, where a single person is responsible for releasing an aircraft, represents a potential weakness in the de-icing workflow.