ASW 12 short landing and collision at Thun airfield
On March 29, 1987, an ASW 12 experienced a short landing at Thun airfield in Switzerland. The pilot, who was familiarizing himself with the aircraft, deployed the braking parachute during final approach. The braking effect was stronger than anticipated, leading to a short landing. The glider collided with a shrub stump and a metal fence, resulting in severe damage to the aircraft. The pilot sustained serious injuries. The investigation found that the parachute release mechanism was not fully engaged.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.