Supervisory inexperience and communication problems resulted in a de-icing worker being badly injured after a KLM Boeing 747-400 toppled an elevating platform at Amsterdam Schiphol.
The aircraft (PH-BFB) had parked on position P14 at de-icing platform J - located just south of the Runway 09 threshold - before a departure to Curaçao on 30 November 2010.
Investigators from the Dutch Safety Board say the supervisor, overseeing a team of four de-icers, had only been in the role for four days.
During the de-icing process, when aircraft communication is handed to a localised control facility, the supervisor says radio messages can be heard from other de-icing positions - a situation that "disturbed" the work.
Two elevating de-icing vehicles were still coating the horizontal stabiliser on each side of the 747 when the supervisor - in a car to the left of the aircraft - cleared the crew to contact ground control for taxiing.
While the de-icer on the right moved to a safe position, the one on the left was still working when the aircraft received clearance to taxi to Runway 36L. It moved forward, knocking over the 10m (33ft)-high de-icer. Its worker sustained serious back injuries in the fall.
The accident bore a striking similarity to a collision that killed three workers de-icing a Royal Air Maroc 747-400 at Montreal in January 1995.
Dutch investigators say the supervisor at Amsterdam, who had completed training on 5 November but only started duty in the week of the accident, had received insufficient supervision and had "lost track" of the process. Communications had been problematic, and the inquiry points out that having a single person releasing an aircraft was a "weak link".