ASK 21 turnback after winch cable-break ends in tail-first impact

An ASK 21 was substantially damaged on a turnback after a simulated cable break during a winch launch at Olten; both occupants uninjured. The instructor held 437 hours on type but had not flown a winch launch for years and had no prior winch instruction; the student was on his fourth winch launch. After a normal climb on RWY 05 the instructor released, estimating 120-150 m AGL — a witness said about 50 m. The pilot pushed down, double-released and said he would land straight; the instructor called a left turn. At 45 degrees off heading airspeed decayed and takeover came too late; the tail struck first and the fuselage broke behind the wings.

1. Training winch course, 4th launch: The pilot, working toward a winch-launch endorsement, was making his fourth winch launch ever, during a two-day course held away from the home airfield, which has no winch.
2. Instructor: 11-yr winch gap: The instructor had last flown a winch launch in 2003, an eleven-year gap, and had never instructed one, despite completing three refresher winch launches earlier that morning.
3. Misjudged release at ~50 m: The instructor released the cable after estimating a height of 120-150 m AGL, but a ground observer later put the actual release height at about half that, around 50 m AGL.
4. Pilot pushes, releases, plans straight: The pilot pushed the nose down less aggressively than the instructor expected, double-released to confirm the cable was free, and continued straight ahead at about 90 km/h.
5. Instructor calls turnback: Judging the remaining runway insufficient, the instructor told the pilot to turn left for a 180° return and land in the opposite direction, and the pilot began the turn.
6. Speed decays at 45° off heading: About 45° into the turn, noticing low airspeed and sluggish controls, the instructor took over and pushed the nose down while banking hard left to regain speed toward the runway.
7. Late takeover, tail-first impact: Control response returned only metres above the ground; the tail struck first, the elevator broke off, and the fuselage broke behind the wings, but both occupants escaped uninjured.