Cat. 2 investigation report: simplified-format report, adapted to the circumstances of the occurrence and the investigation stakes.
After taking off from Valloire Bonnenuit mountain airstrip, the pilot headed north towards Valloire then Valmeinier, then south towards the Terre Rouge refuge and Mont Thabor. At the end of the valley probably near the refuge, the pilot turned around. He headed north and climbed following the terrain at low height.
When he arrived at the plateau, near the dilapidated sheep shed, for an unknown reason, the pilot made a sudden action (possibly by instinct in the light of an immediate danger) on the cyclic stick. This action caused a rotor blade flapping phenomenon, which destroyed a section of the vertical tailplane and damaged the pusher-propeller blades. This damage rendered the microlight uncontrollable and the pilot was unable to avoid the collision with the snow-covered ground.