Summary
On 5 July 1964, a Rhönlerche II glider, registration HB-708, operated by Segelfluggruppe Winterthur, was involved in an accident at Winterthur-Hegmatten airfield. The aircraft was damaged but the pilot was uninjured.
Aircraft and Pilot Information
The glider was a Rhönlerche II with a maximum takeoff weight of 400 kg. It held a valid airworthiness certificate issued on 30 August 1962, valid until 18 August 1964. The aircraft was owned and operated by Segelfluggruppe Winterthur.
The pilot was a student pilot born in 1943, holding a learner permit for motor and glider aircraft issued on 8 May 1961. He had a total flight experience of 16 hours and 20 minutes over 150 flights, approximately two-thirds of which were on the Rhönlerche II.
Accident Details
On the day of the accident, the glider club was operating from the newly opened Winterthur-Hegmatten airfield for the first time. The duty flight instructor briefed all pilots and students on the local conditions and traffic patterns. He conducted a familiarization and control flight with the student in the same aircraft on dual controls, which he deemed satisfactory. The instructor then instructed the student to perform a solo traffic pattern flight.
The student pilot launched via winch at 1451 hours local time, reaching an altitude of 260 meters above the airfield. After circling southwest of the village of Wiesendangen, he returned to the airfield and descended to approximately 100 meters above the airfield at the prescribed point southeast of runway threshold 05. He then initiated the approach, similar to the previous control flight. Over the water surface of a gravel pit located in the extension of the runway, he encountered a downdraft. The altitude was insufficient to reach the airfield. The pilot flew just above the water surface, which was about 4 meters lower than the airfield, then touched down on a gravel bank at 1456 hours and collided head-on with the edge of the gravel pit, where the aircraft came to a stop with damage.
Damage
The pilot remained uninjured. The glider sustained damage to the front fuselage and wing attachments, with repair costs estimated at approximately 1800 Swiss francs or about 20% of the aircraft's value. No third-party damage occurred.
Conclusion
The accident resulted from the student pilot misjudging his height during the landing approach and additionally encountering an unexpected downdraft on final approach, which forced him to land before the airfield in unfavorable terrain, where damage to the aircraft could not be avoided.