Incident
On Sunday, 3 August 1961, at approximately 1420 MEZ, a student pilot of the Austrian Aero Club began a winch launch from grass runway 28 at Altenrhein airfield for a circuit. The student had previously completed two flights that day, during which the flight instructor noted a tendency to fly too slowly. After releasing from the winch at about 300 m, the student flew the prescribed left-hand circuit and turned onto final approach at about 80 m. The aircraft was slightly to the right, parallel to the runway. The student attempted to correct with right rudder and then left aileron to initiate a left sideslip. At an altitude of about 40 m, the glider stalled, banked right, entered a right spin, and after approximately one and a half turns struck the ground at 1424, about 20 m to the right of the runway centerline and 500 m before the threshold. The student sustained serious injuries (including multiple bone fractures), and the glider was heavily damaged.
Aircraft and Pilot
The glider was a Grunau Baby III, registration OE-0231, manufacturer serial number 03, built 1953/56. It was a single-seat, braced high-wing wooden aircraft with fabric covering, owned by Sportfliegergruppe Bregenz, Austria. The airworthiness certificate was valid until 24 May 1962. The glider was equipped with an airspeed indicator with marked minimum speed. No technical defects were found.
The student pilot, born 1931, held an Austrian glider student license and had already passed both practical and theoretical examinations for his glider pilot license (the license was issued on 6 October 1961). He had approximately 100 flights, about 60 on the accident type.
The flight instructor, born 1920, held an Austrian glider instructor rating since 24 March 1954 and a private pilot license.
Investigation
The accident was initially reported as minor, so the Federal Air Office handled the investigation. On 27 October 1961, a preliminary investigation was opened. Questionnaires were sent to the instructor and student on 1 March 1962; the student did not respond. The investigation report was submitted on 6 April 1962. The commission noted the excessive duration of the preliminary investigation.
The accident occurred on Altenrhein airfield, on flat terrain north of the paved runway 28, coordinates 261.700/759.500, elevation 400 m. Weather was fine and cloudless with a weak north wind of 4 knots.
Discussion
It is highly probable that the student paid insufficient attention to maintaining adequate airspeed when initiating the sideslip. Contributing factors may have been that he began the sideslip from a slightly offset approach and did not use the correct control sequence (aileron before rudder).
The instructor had applied for permission to conduct glider training at Ragaz airfield but was denied. He then moved the group to Altenrhein based on a prior arrangement with the airfield chief, who allowed operations after being told that permission was still pending.
Conclusions
The Federal Aircraft Accident Investigation Commission unanimously concluded that the accident was with high probability caused by undershooting the stall speed during the initiation of a sideslip in the landing approach.