ASK 21 winch power loss at low altitude — driver misinterpreted noise as cable break

During a winch launch at Rheinstetten, both occupants of an ASK 21 were seriously injured in a hard landing; the glider sustained minor damage. After only marginal altitude gain, the winch driver heard a loud noise, took it as a cable break, and reduced power. Tension fell, the cable detached from the glider, and the glider transitioned from shallow climb to steep descent, impacting nosewheel-first about 213 m from launch. After the accident the cable, fall-parachute, weak link and pre-cable were all found intact in front of the winch; the cable had not actually broken.

1. Second winch launch of the day: An ASK 21 (1983 build, 600 kg MTOM) on a planned ~30-minute local instructional flight from the Segelfluggelände Rheinstetten. Pilot (59, LAPL(S), 1,624 h total, ~300 h on type, 400+ winch launches). The first winch launch had been normal (release at ~300 m AGL, no thermal found, landed in opposite direction). Second launch began 15:34:40 on an electric Ulbrich ESW-2B winch (5 mm Dyneema cable, ~600 m to the launch point). Wind 040° at 5 km/h, 28 °C.
2. Low altitude in initial climb phase: BFU notes (historical safety publications V39 1985, V63 1987, V92 1991, V139 1995): winch-launch interruptions in the initial climb phase are particularly hazardous. Statistics V92 (1991): launch interruptions account for 12% of all glider accidents, 26% of fatals, 28% of seriously-injured cases. The pilot made few control inputs at start; the glider gained only marginal altitude and stopped climbing.
3. Winch driver reduced power on noise: The winch driver heard a loud noise from the winch, interpreted it as a cable break, and pulled the power-control slider back somewhat — reducing the cable pull on the glider in the low initial-climb phase.
4. Cable tension fell, cable separated: With the reduction in cable pull, the cable went slack; the cable parachute deployed and the cable separated from the glider. The start director, watching the launch and seeing the parachute deploy, called 'Halt, stopp' to the winch driver, who then fully retarded the throttle (the winch then auto-braked).
5. Steep descent, no recovery: The pilot stated that after the cable detached the glider went very steeply toward the ground and he was unable to arrest the descent before ground contact. The passenger described the glider as having stopped climbing, then the nose dropped and it dived steeply.
6. Nosewheel impact ~213 m from launch: First touchdown was on the nosewheel ~213 m from the launch point, leaving a 6 m ground scar. A second touchdown 22 m further, then a 115 m curving roll trace to final position 137 m further on. Both occupants seriously injured. Damage: cracks in the main-wheel fairing only; all control surfaces present and functional; no structural damage. Post-accident inspection: tow cable, fall-parachute, breakable link (status 'black') and pre-cable with double-ring pair were all connected and lying in front of the winch — the cable had not actually broken.