What happened
On Sunday, July 6, 2003, at 13:15, a Humbert Tetras ultralight aircraft, identified as 83-SL, crashed in the vicinity of Pralloagnan-la-Vanoise, France. The flight, which was a private pleasure trip, began earlier that morning with a departure from Albé at 10:05.
After approximately three hours of flight, the aircraft flew over Pralognan-la-Vanoise and entered a valley at a low altitude. An eyewitness with aeronautical knowledge observed the aircraft performing a left-hand turn to reverse direction. During this maneuver, the aircraft's bank angle increased as it approached the terrain. The witness noted that the aircraft appeared to be flying at a low speed, roughly 100 meters above the ground, before entering a spin and striking the terrain. There were no visible engine malfunctions reported by the witness.
Navigation charts and a flight log detailing various waypoints—including Belfort, Pontarlier, Bellegarde, Annecy, and Albertville—were recovered from the wreckage. However, no GPS unit was found at the scene. The valley into which the pilot had entered does not lead to the intended destination of Tignes; reaching Tignes from Pralognan would have required crossing terrain exceeding 2,000 meters.
The investigation
The investigation focused on the flight path and the aircraft's performance relative to the terrain. Investigators examined the recovered navigation documents and the sequence of the turn observed by the witness. The investigation established that the aircraft was a new unit, purchased only three weeks prior to the accident. The pilot was an experienced flyer with a PPL held since 1976 and a total of 722 flight hours, though only 6 hours and 50 minutes had been completed on this specific type in the month preceding the event.
Findings
- The accident resulted in two fatalities, involving both the pilot and the passenger.
- The aircraft was destroyed upon impact.
- The primary cause of the accident was the insufficient consideration of the environment in relation to the performance capabilities of the aircraft during the turn.