What happened
On July 26, 2024, a CAPRONI Calif A-21S glider, registration F-CALI, was performing a towed take-off from the Aspres-sur-Buëch aerodrome. During the initial climb, at an altitude of approximately 100 feet, the engine of the towing aircraft experienced irregular operation. The tug pilot responded by adopting a nose-down attitude and switching fuel tanks to restore power.
Observing the engine trouble and the descending attitude of the tug, the glider pilot decided to release the tow cable. Following the release, the glider pilot attempted a U-turn to return to the runway on the opposite heading. During this maneuver, the glider's right wing struck the perimeter fence of a nearby photovoltaic array field. The impact destabilized the aircraft, causing it to collide with solar panels and come to a stop on the ground. The accident resulted in two injuries (the pilot and passenger) and the destruction of the glider.
The investigation
The investigation examined the flight sequences of both the tug and the glider, as well as the maintenance and pilot history. The tug pilot reported that the engine spluttered due to an insufficient amount of fuel in the selected tank. The glider pilot, seated in the right seat, performed the turn without checking his altitude or airspeed. Investigators also reviewed the aerodrome's safety briefing procedures and the pilot's familiarity with local landing sites.
Findings
Several factors contributed to the accident:
- The tug pilot had overestimated the remaining fuel in the active tank, leading to the engine malfunction during the climb.
- The glider pilot made an incorrect estimation of his altitude relative to the aerodrome when deciding to attempt a U-turn.
- The pilot's view of the valley below the plateau may have biased his perception of his actual height.
- A lack of specific knowledge regarding immediate alternative landing fields, combined with a lack of a formal safety briefing regarding local off-field landing areas, hindered the pilot's decision-making during the emergency.