History of the Flight
The flight began on 1 August when the pilot reserved the DR400-500 for a family sight-seeing cross-country trip. After picking up his two children in Haguenau, the pilot flew to Annecy on 3 August. On 5 August, the aircraft departed Annecy at 14:22 bound for Sarlat. The pilot informed the controller of his intention to overfly Lake Annecy before leaving the frequency at 14:28.
After crossing the lake, the pilot followed a valley southward, climbing to approximately 3,700 ft. Passing Albertville, he continued south into the valley toward Saint-Jean-de-Maurienne, descending to 3,000 ft. After passing Saint-Rémy-de-Maurienne aerodrome, he turned southwest into the valley leading to the Col du Glandon pass. At the valley entrance, the aircraft was at about 3,200 ft, giving a height of 1,500 ft above the valley floor.
The pilot flew up the valley, roughly following the road at its center. The aircraft climbed with a mean gradient of 5.1%, below the valley's mean gradient. Although altitude increased, the aircraft's height above ground progressively decreased due to rising terrain.
Witnesses saw the aircraft strike trees, catch fire, and then hit the ground. They assisted the conscious passenger, moving her from the burning wreckage, but could not help the other occupants.
Meteorological Information
Météo-France reported that an influx of moist air preceded the low layers of a cold front, producing fairly dense altocumulus clouds in the afternoon that could have caused light precipitation over higher ground. The sky was estimated to be very cloudy between 3,000 ft and 6,000 ft across the region, but precise cloud cover in the valleys near the accident site could not be determined. At the accident site, conditions were estimated as wind from 280° at 5 kt gusting 15 kt, few to scattered clouds, temperature 10 °C, dew point 8 °C. Witnesses in the valley described very good weather with sunny skies and isolated clouds, calm or light winds. A photo taken less than an hour after the accident showed blue sky with isolated clouds.
Aircraft Information
The DR400-500, registered F-HMYY, was equipped with a Lycoming IO-360 engine (200 hp at 2,700 rpm) and a variable-pitch propeller. It had two wing fuel tanks (40 L each), a main fuel tank (105 L), and an auxiliary fuel tank (90 L). The aircraft was fitted with a two-axis autopilot and a Garmin GNS430 system. Weight and balance estimates, based on occupant weights, baggage, and probable fuel quantity, indicated the aircraft was very likely near maximum takeoff weight and aft center of gravity limits. No technical failure was identified as contributing to the accident. The flaps were in the retracted position at impact, and the engine was delivering power.
Pilot Information
The 51-year-old pilot held a private pilot license (issued 2011) with a single-engine piston rating and a valid class 2 medical certificate. He had approximately 230 flight hours, including about 50 hours on DR400 aircraft at Aéroclub de Loire Atlantique. In 2021, he flew just over ten hours, including three familiarization flights on F-HMYY totaling 2.5 hours, after which he was approved for the type. His instructor noted no difficulties and that he quickly adapted to the aircraft's features. Club members described the pilot as diligent, confident but not risk-taking, and comfortable with IT tools. He had no known experience flying in mountainous terrain.
Wreckage and Site Information
The wreckage was found at 5,070 ft elevation, about 2.4 km from the Col du Glandon pass, near the road. The valley gradient averaged about 8.4% from the entrance to the accident site. The aircraft struck vegetation at about eight meters height with wings level, a nearly horizontal flight path, and significant horizontal speed. Impact and fire destroyed the aircraft. Examination confirmed flight control continuity on all three axes and engine power at impact. Elevator and rudder trim positions could not be verified.