Accident Summary
On June 2, 1970, at 1819 local time, a Schleicher K 8 B glider, registration HB-831, sustained serious damage during a landing accident at Bellechasse airfield in Vully-le-Bas, Switzerland. The student pilot, who was flying solo for the sixth time and for the second time in this type of glider, was uninjured.
Investigation
The Federal Commission of Inquiry into Aircraft Accidents opened an investigation on June 3, 1970. The glider had been moved to a hangar but nothing had been altered. Ground marks were clearly visible. Canton authorities did not participate in the investigation.
Aircraft and Pilot Information
The K 8 B, manufactured by Schleicher in 1965, was a single-seat training glider with a cantilever wing, mixed construction (wooden wings, steel tube fuselage), aerodynamic brakes, and a brakeble fixed wheel. Its airworthiness certificate was valid until March 31, 1971. At the time of the accident, the glider had accumulated 342 hours and 10 minutes of flight time and 378 starts without prior incidents.
The student pilot, born in 1940, held a valid student pilot card issued on September 17, 1964. He began training in 1964, with interruptions, and resumed on May 3, 1970. His first solo flight was on June 1, 1970. He had logged 12 hours and 48 minutes of flight time and 84 starts, including 9 hours and 29 minutes and 38 starts at Bellechasse. His instructor described him as a serious student with normal progress. His medical examination on April 24, 1970, showed good health.
Flight History
The student made his first flight on the K 8 B that day from 1723 to 1740 hours under his instructor's supervision. During the debriefing, the instructor noted that the student should avoid repeated use of airbrakes to adjust descent. The second flight began at 1803. The student was released at between 500 and 600 meters above ground, flew a downwind leg, performed spirals as instructed, and continued the approach, which he extended slightly due to being high. On final approach at 85 km/h, he extended the airbrakes to half position. Losing altitude quickly against the breeze, he fully retracted them.
The instructor's deposition: At about 20 meters from the ground, the student again extended the brakes despite the earlier remark. The glider pitched down at about 45 degrees. The student pulled up at the last moment, but the nose struck the wheat field. The glider rose to about 10 meters, then entered a right turn. The wing tip struck the ground simultaneously with the fuselage, resulting in a ground loop that turned the glider approximately 180 degrees. The pilot emerged unharmed.
Damage
Pilot: no injuries. Glider: forward lower fuselage crushed, tubes bent, skid broken. Both wing spars abnormally bent, tearing fabric at the root and at the inner ends of the flaps; two left wing ribs broken, as well as the plywood leading edge in that area. Spars did not appear damaged but required inspection. Ground damage negligible.
Discussion
The investigation noted that the student pilot had valid licenses and the glider was in good condition. The student stated that when he extended the airbrakes, he may have inadvertently pushed the control stick forward as a counter-movement. The investigation considered it likely that, since this was only his second flight on this type, he spent one or two seconds searching for the airbrake handle inside the cockpit, thereby losing sight of his flight path at very low altitude, leaving insufficient time to recover.
Conclusion
The accident was due, with high probability, to the action on the elevator control of a glider with which the pilot was not yet familiar.