Atterrissage en campagne et collision avec une clôture d'un Standard Libelle près de Boltigen, Suisse

Le 6 juillet 1976, un planeur Glasflügel Standard Libelle a effectué un atterrissage en campagne près de Boltigen, Suisse. Le pilote, qui avait une grande expérience de vol, a rencontré des conditions météorologiques se détériorant avec une couverture nuageuse croissante et des orages. En tentant d'atterrir, le planeur est entré en collision avec une clôture, causant des dommages importants à l'appareil et des blessures faciales graves au pilote. Le rapport a identifié une décision tardive d'atterrir comme un facteur contributif à l'incident.

1. Aerotow cross-country: After aerotow departure from Zweisimmen, the pilot conducted a cross-country soaring flight in the Alps, adjusting route as cloud cover and thunderstorms developed.
2. Thermal lift deteriorates: In the Simmental, the pilot encountered poor and weakening updrafts and could no longer find reliable thermals to maintain safe altitude.
3. Thunderstorm conditions: Thunderstorms and increasing cloud cover over the Alpine chain created deteriorating soaring conditions with rain and associated sink.
4. Late outlanding decision: While repeatedly overflying suitable terrain for an outlanding, the pilot continued in the hope of finding lift and delayed committing to an outlanding until altitude was low.
5. Commits to Boltigen field: At low height the pilot decided to land in a field south of Boltigen that he had previously used, without the recommended 300 m reconnaissance circuit to check for obstacles.
6. Obstacle avoidance at low: On final approach in headwind, tailwind effects, and rain, the glider lost height, forcing the pilot to deviate around a 30 m construction crane and then just clear a high-voltage line, further reducing energy.
7. Crash - serious injury: With minimal airspeed the glider touched down about 200 m short of the intended field, rolled roughly 8 m in wet grass, and collided with a barbed-wire fence, seriously injuring the pilot and damaging the aircraft.