What happened
On May 26, 2005, a DR 400-180, registration F-GUPV, departed from Chalon Champforgeuil for a VFR navigation flight toward Megève, via the Mont Blanc massif. The flight included the pilot and two passengers. During the flight, the pilot contacted Geneva Information to request transit through the Geneva controlled zone and to fly over the Mont Blanc massif.
After climbing to 10,000 feet and maintaining that level for approximately one hour, the pilot began a climb through flight level 105 up to 15,000 feet. During this ascent, the aircraft reached altitudes exceeding the regulatory requirements for unpressurized aircraft. Radar data indicated that in the final minutes of the flight, the aircraft was flying in a straight, level path directly toward the mountain face. The aircraft struck the south-western slope of Col Major at approximately 4,650 meters, resulting in three fatalities and the destruction of the aircraft.
The investigation
The investigation examined the aircraft wreckage, radar tracks from Geneva, and meteorological conditions. Investigators found that the aircraft hit the terrain with low energy, with the left landing gear and engine striking the slope first. The engine was still functioning at the time of impact.
Witness testimony from another pilot flying in the area noted that the F-GHDV appeared to be flying very close to the mountain walls, approximately 50 meters from the terrain. The witness also reported that the pilot of the aircraft provided incoherent responses on the radio frequency, which the witness associated with the symptoms of hypoxia.
Findings
- The pilot elected to conduct a high-altitude flight without the required oxygen inhalation equipment for the crew or passengers.
- The aircraft was flying at altitudes (up to 14,500 feet) that necessitated supplemental oxygen under French regulations for unpressurized cabins.
- Hypoxia is the most likely cause of the accident, as the lack of oxygen likely impaired the pilot's judgment and flight capabilities.
- The pilot's ability to perceive the terrain was likely further compromised by a lack of visual contrast against the snow-covered slopes and the physiological effects of hypoxia on peripheral vision.