What happened
On June 14, 2015, a Schleicher ASK21 glider, registration F-CIFM, was preparing for a winch-assisted takeoff at the Bagnoles de l’Orne Couterne aerodrome. The flight was intended to be a demonstration flight for the airfield's 50th anniversary. The aircraft was positioned approximately 100 meters before the threshold of the unpaved runway in an area where the grass height was approximately 40 cm.
As the winch cable tensioned and the glider began its takeoff roll, a wing walker positioned on the leeward side maintained the left wing in a horizontal position for several meters before releasing it. Following this release, the glider tilted sharply to the left, causing the left wing to contact the ground. The pilot attempted to correct the inclination using the control stick, which reduced the tilt, but the aircraft entered a left turn with a descending pitch. During this sequence, the winch cable detached spontaneously without intervention from the crew. The glider subsequently struck the ground at an approximately 60-degree nose-down attitude and a 10-degree left bank. The aircraft sustained damage, but no injuries were reported.
The investigation
The BEA investigation utilized video recordings from a nearby observer and testimonies from both the pilot in the front seat and the instructor in the rear seat. The investigation examined the aircraft's positioning, the environmental conditions, and the crew's operational procedures. Investigators noted that the aircraft had been rented only two weeks prior and had not yet flown at the club. The investigation also reviewed the maintenance of the airfield's unpaved runway, noting that the grass had not been recently mown due to delays in contracting mowing services.
Findings
Several factors contributed to the loss of control. The primary cause was the decision to perform a winch takeoff in an area of tall, unmaintained grass, which destabilized the glider during the takeoff roll. This instability was exacerbated by the following factors:
- The wing walker was positioned on the leeward side of the aircraft.
- Insufficient aileron input to counteract the crosswind.
- The physical contact of the left wing with the tall grass, which created drag and braking forces on that side.
Additionally, the crew's decision to continue the takeoff attempt rather than immediately releasing the cable was influenced by the high-pressure, dynamic nature of the takeoff phase. The pilot's focus on correcting the wing tilt likely took priority over the immediate release of the cable. The investigation also noted that the instructor's hand was not on the release handle, a factor attributed to overconfidence and fatigue. While the spontaneous detachment of the cable likely prevented a full cartwheel or inversion, the combination of environmental conditions and operational decisions led to the accident.