Accident Summary
On 7 April 1985 at 1416 local time, the Standard Cirrus glider HB-1067 crashed at Wiesendangen, Switzerland, following an inadvertent tow cable release during a winch launch at Winterthur airfield. The pilot, performing a shortened circuit for runway 21, stalled on base leg and spun into the ground.
Aircraft and Pilot Details
The aircraft was a Standard Cirrus single-seat glider (span 15 m, shoulder-wing GRP with T-tail), manufactured in 1973 by B. Grob (license Schempp-Hirth), serial number 183 G. It was owned by Segelfluggruppe Winterthur and had a valid airworthiness permit until 31 March 1988. The pilot, a Swiss citizen born in 1948, held a glider pilot license issued 4 May 1983, with ratings for winch towing and passenger carriage. His total flight experience was 112 hours and 18 minutes with 283 launches, 227 of which were winch launches. Transition training on the accident type occurred 8 September 1984, comprising four launches (two winch, 41 minutes). After a winter break, he completed two check flights with an instructor and three additional solo flights before the accident, all winch launches. The accident flight was his first solo flight on the type since transition.
Sequence of Events
The launch began at 1408 local time. The initial climb was somewhat steep. At approximately half the winch height (150 m above ground), the tow cable released inadvertently. The pilot immediately pushed the nose down and turned left to fly a shortened circuit for a normal landing on runway 21. After turning onto base leg, flown quite tightly, the glider visibly slowed. Suddenly, at an altitude of 80–100 m above ground, it stalled, dropped its left wing, and after one rotation struck the ground nose-first in a steep attitude. The impact occurred about 400 m before the runway 21 threshold and 250 m left of the centerline.
Weather Conditions
The weather was influenced by a high-level warm front with a westerly flow. Sky cover was 2/8 altocumulus at 3000 m and 2–4/8 cirrus. Visibility was very good. Wind was from the southwest at 5–10 knots, gusts to 15 knots. Temperature was +15°C, sun azimuth 196°, elevation 49°. Gliding weather forecast indicated moderate thermals weakening from the west.
Wreckage and Injuries
The glider was destroyed. The forward fuselage and canopy were shattered; the fuselage tube broke behind the wing and near the fin. The right wing was fractured in the aileron and center sections. Control continuity was confirmed, landing gear was extended, and rudder pedals were locked in the forward position. No pre-existing technical defects were found; weight and center of gravity were within limits. The pilot, properly restrained and carrying a parachute, sustained fatal injuries due to severe internal impact trauma. No alcohol was detected.
Findings and Cause
The tow coupling showed no pre-existing defects and likely opened automatically because the angle between the fuselage and tow cable exceeded the maximum permissible 70°. The pilot’s initial reaction (pushing the nose forward) was correct. The aircraft stalled and spun left due to falling below the minimum flight speed before turning onto final approach.