Incident SHK 1 à Schänisberg : pilote blessé après une vrille
Le 30 avril 1967, un planeur Schempp-Hirth SHK 1 a été impliqué dans un accident à Schänisberg, Suisse. Après un vol de trois heures, le planeur est entré en vrille lors d'un virage, entraînant un crash sur une pente boisée. Le pilote a subi de graves blessures mais a survécu. L'enquête a confirmé que l'incident a été causé par une entrée en vrille due à une vitesse insuffisante pendant le virage.
- Cruise ridge soaring: After about three hours of soaring in good thermals, the pilot was ridge-soaring in weak lift along the northwest slope of the Schäniserberg with the wooded steep hillside close on his right.
- Low speed in turn: While flying along the slope the pilot was using approximately 75 km/h, the speed for minimum sink, which was below the minimum safe speed for a 45° banked turn in this glider.
- Stall entering turn: During a left turn at about 45° bank with insufficient airspeed, the controls became soft and the glider began to drop its left wing and depart into a spin.
- Attempted spin recovery: The pilot neutralized the ailerons, pushed the stick forward, and applied full opposite rudder, briefly stopping the rotation and putting the glider on a southwest heading.
- Spin re-entry near slope: Concerned by the rapidly approaching terrain, the pilot applied right aileron to turn away from the slope, causing the glider to enter another left spin with insufficient height to recover.
- Crash - serious injury: After completing a total of about three spin turns, the glider impacted trees on the steep wooded slope of the Schäniserberg and was destroyed, and the pilot sustained serious injuries.