What happened
On April 20, 2011, a Centrair ASW20 F glider, registration F-CFLN, was preparing for a winch takeoff on the unpaved runway 32 at Chambéry Challes les Eaux. During the takeoff roll, the winch operator noticed the cable parachute beginning to inflate and subsequently reduced power to trigger a cable release. Simultaneously, the safety starter requested an immediate increase in winch power.
Following the release, the pilot experienced difficulty managing the aircraft's flaps, failing to move the lever to the second landing setting. While maintaining a nose-down attitude, the pilot performed a landing on the runway centerline. During the landing roll, the pilot attempted to use the brakes, but the braking system proved ineffective. The glider's right wing struck the winch truck, causing the aircraft to pivot 90 degrees and subsequently strike a vehicle parked behind the truck. The aircraft sustained heavy damage.
The investigation
The investigation examined the sequence of events following the cable release and the pilot's decision-making process. Investigators looked into the mechanical state of the aircraft, specifically the effectiveness of the braking system and the flap mechanism. The investigation also reviewed the coordination between the winch operator and the safety starter, as well as the pilot's flight path management during the aborted takeoff.
Findings
- The pilot's inadequate management of the flight path following the cable release was the primary cause. The pilot became preoccupied with adjusting the flaps and managing the landing roll, leading to a late realization of the impending collision with the winch truck.
- The pilot's decision to proceed with the takeoff despite a known deficiency in the braking system contributed to the accident.
- Contradictory instructions between the winch operator and the safety starter created confusion during the critical phase of the takeoff.
- The unexpected cable release occurred during a transition in pitch attitude, complicating the pilot's decision-making between landing on the runway centerline or performing a short circuit.