Ka 6 BR rencontre des changements météorologiques soudains lors de l'approche à l'aérodrome de Montricher

Le 19 mai 1973, un planeur Ka 6 BR a été impliqué dans un incident à l'aérodrome de Montricher en Suisse. Le pilote, lors de son premier vol d'entraînement de la saison, a rencontré des conditions météorologiques se détériorant rapidement en raison du passage d'un front froid. Malgré les efforts pour ajuster l'approche, des vents forts et des courants descendants ont forcé le planeur à atterrir avant la piste, entraînant des dommages importants à l'appareil. Le pilote est resté indemne et aucune blessure n'a été signalée. L'enquête a confirmé que les conditions météorologiques soudaines et défavorables étaient le principal facteur de l'incident.

1. Aerotow local soaring: The pilot departed Montricher by aerotow for his first training flight of the season and climbed in 1–3 m/s lift in the Mont-Tendre area.
2. Weather deteriorates rapidly: A fast-moving cold front with strong gusts and rapidly worsening conditions approached, and at 2050 m QNH the pilot was instructed by radio to return due to the deteriorating weather.
3. Strong gusty headwind: On return overhead the field the pilot estimated a strong surface wind of about 43 km/h from the windsock, with actual conditions including stronger gusts and turbulence than he anticipated.
4. High approach, airbrakes used: Turning onto final for runway 21 at about 230 m AGL, the pilot judged himself too high and partially extended the airbrakes, reducing his altitude margin.
5. Insufficient altitude margin: By the time a colleague on the ground advised him to retract the airbrakes, the remaining altitude was no longer sufficient to comfortably reach the runway threshold in the strong wind.
6. Downdrafts on short final: On short final at 110–120 km/h the pilot encountered stronger-than-expected headwind and reported passing through a zone of downdrafts, further degrading his glide path after crossing the nearby railway line.
7. Outlanding - damage: Unable to reach the runway, the glider touched down into a 4–5 m high hedge about 175 m short of the threshold, yawed a quarter turn left, and was badly damaged while the pilot remained uninjured.