What happened
On 28 October 2019, a Schleicher ASK 13 glider, registered F-CLBG, was performing a towed takeoff from the Havre Saint-Romain aerodrome. The flight was an instructional solo session involving a student pilot. Approximately 25 seconds after the aircraft left the ground, the glider canopy suddenly and fully opened while the aircraft was at a height of roughly 10 meters and traveling at 120 km/h.
As the student pilot attempted to close the canopy, the glider continued to climb along the runway centerline. During this period, the glider rose above the level of the tug aircraft. Observing the glider ascending above him, the tug pilot made the decision to release the tow cable at an altitude of approximately 40 meters. Following the release, the glider reached a height of about 80 meters before turning left. During this maneuver, the glider stalled and collided with the ground in a nearby field. The accident resulted in one student pilot seriously injured and the destruction of the glider.
The investigation
The BEA examined the wreckage, the flight data from the FLARM system, and onboard video. Investigators confirmed that the flight control linkages were functional and the release system was operational. The investigation focused on the canopy locking mechanism, noting that while the locking system showed no mechanical damage, the canopy was found unlatched. The investigation also reviewed the student pilot's training progress and the procedures followed by the tug pilot during the emergency cable release.
Findings
The primary cause of the accident was the untimely opening of the canopy, likely because it had not been correctly locked prior to departure. Several contributing factors were identified:
- The intense psychological stress placed on the student pilot by the sudden canopy opening.
- A potential preoccupation with managing the canopy at the expense of maintaining flight controls.
- Altered glider aerodynamics caused by the open canopy and potentially inadequate elevator trim.
- The limited flight experience of the student pilot.