What happened
On June 27, 2004, at approximately 17:00, a Centrair C 101 A glider, registration F-CGFT, was engaged in a local flight near the Bagnères-de-Luchon aerodrome. The pilot had taken off in tow and released from the tow plane at an altitude of approximately 1,000 meters along the Superbagnères slope. During the flight, the pilot navigated toward Montaubande-Luchon and the Col du Portillon, experiencing difficulty locating thermals due to weak lift. After roughly 2 hours and 45 minutes of flight, the pilot initiated a right-hand turn to return to the airfield. During this maneuver, at an altitude of about 50 meters, the aircraft encountered a sink zone. The left wing dropped, and the glider struck the treetops before plunging into the vegetation in a steep nose-down attitude. The aircraft's nose struck the ground, though the fuselage remained intact, despite damage to the right wing and left aileron.
The investigation
The investigation focused on the flight trajectory and the meteorological conditions present at the time of the accident. Investigators reconstructed the flight path based on the pilot's testimony and analyzed the atmospheric layers in the Luchon valley. It was established that the valley was subject to a northerly current up to approximately 2,000 meters, while a warmer southerly current existed above this level, with lift terminating near 1,800 meters. The investigation also examined the pilot's decision-making process regarding the timing of the return flight.
Findings
- The pilot made a late decision to perform a turnaround to return to the aerodrome.
- The aircraft encountered descending air (sink) during the turn at a very low altitude.
- The pilot's altitude was insufficient to recover from the wing drop caused by the sink zone.
- Meteorological conditions included a south/southwest flow at altitude and a light north/northwest surface wind.