Atterrissage court et collision de l'ASW 12 à l'aérodrome de Thoune

Le 29 mars 1987, un ASW 12 a effectué un atterrissage court à l'aérodrome de Thoune en Suisse. Le pilote, qui se familiarisait avec l'appareil, a déployé le parachute de freinage lors de l'approche finale. L'effet de freinage a été plus fort que prévu, entraînant un atterrissage court. Le planeur a heurté une souche d'arbuste et une clôture métallique, causant de graves dommages à l'appareil. Le pilote a subi de graves blessures. L'enquête a révélé que le mécanisme de libération du parachute n'était pas complètement engagé.

1. Aerotow — landing: During the second instructional familiarization flight in the ASW 12, the pilot returned to Thun airfield for landing in increasing wind and strong lift in the circuit area.
2. Braking chute deployed: On final approach to runway 32, the pilot extended full positive flaps and deployed the braking parachute, which produced a much stronger decelerating and sink effect than he had anticipated.
3. Incomplete system familiarization: Preflight preparation did not include fully exercising the braking parachute control through its entire range or practicing the jettison action, leaving the pilot unfamiliar with the exact feel and travel needed to release the chute.
4. Attempted chute release: Realizing he would land short, the pilot attempted to jettison the braking parachute and believed he had pulled the handle to its stop, but in fact likely pulled only to the cable tension 'pressure point' and not far enough to actuate the release.
5. High sink continues: Although he retracted the flaps after the attempted release, the high sink rate persisted with the braking parachute still effective, causing the glider to touch down before the runway, bounce, and then collide with a shrub stump.
6. Crash - serious injury: After striking the shrub stump, the glider fell onto a metal tube fence near Thun airfield, was severely damaged, and the pilot sustained serious injuries.