Atterrissage en campagne du Grunau Baby II près de Holderbank entraîne des dommages importants
Le 9 juin 1964, un planeur Grunau Baby II a effectué un atterrissage en campagne près de Holderbank, en Suisse. Le pilote, participant à un cours de formation, a rencontré des descendances inattendues qui ont conduit à la décision d'atterrir en dehors de l'aérodrome désigné. Bien qu'une zone d'atterrissage appropriée ait été choisie, l'approche s'est faite avec un vent arrière, entraînant un atterrissage dur et des dommages importants à l'appareil. Le pilote est resté indemne, mais le Grunau Baby II a été considéré comme une perte totale. L'enquête a noté une erreur de jugement du pilote concernant la direction du vent lors de l'atterrissage.
- Cross-country soaring: During a training week, the pilot launched from Birrfeld in a Grunau Baby II to attempt a five-hour soaring flight and had been airborne for over three hours.
- Strong downdraft encountered: While flying near Wildegg-Holderbank at about 500 m above ground, the glider suddenly encountered strong sink of approximately 4 m/s.
- Low experience level: The young pilot had limited gliding experience, with about 19.5 hours total and only 6.5 hours in the preceding days of the course.
- Abandons return to field: After attempting to head back toward Birrfeld, the pilot realized he no longer had sufficient height to clear the Kestenberg ridge and decided to perform an outlanding instead.
- Tailwind landing approach: The pilot selected a generally suitable field but flew the approach in the wrong direction, landing with a tailwind and in a slipping attitude, apparently without using visible smoke from nearby chimneys to determine wind direction.
- Unstable touchdown: Because of the tailwind and slipping approach, the glider touched down too fast and in poor attitude, leading to loss of control on ground contact.
- Outlanding - damage: The glider broke apart on the off-field landing near Holderbank, sustaining 70–80% structural damage and being written off, while the pilot remained uninjured.