Standard Libelle outlanding and collision with fence near Boltigen, Switzerland
On July 6, 1976, a Glasflügel Standard Libelle experienced an outlanding near Boltigen, Switzerland. The pilot, who had extensive flying experience, encountered deteriorating weather conditions with increasing cloud cover and thunderstorms. While attempting to land, the glider collided with a fence, resulting in significant damage to the aircraft and serious facial injuries to the pilot. The report identified a late decision to land as a contributing factor to the incident.
- 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.
- Thermal lift deteriorates: In the Simmental, the pilot encountered poor and weakening updrafts and could no longer find reliable thermals to maintain safe altitude.
- Thunderstorm conditions: Thunderstorms and increasing cloud cover over the Alpine chain created deteriorating soaring conditions with rain and associated sink.
- 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.
- 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.
- 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.
- 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.