Summary
On 26 June 1964, a Rhönlerche II glider, registration HB-721, operated by the Gliding Group of Granges (Granges, SO), was destroyed in a collision with terrain on the south slope of Bettlachstock at an elevation of 1140 m. The student pilot, who was conducting an altitude-gain flight as part of his training, was uninjured. The glider sustained 80% damage.
Aircraft and Pilot Information
The glider was a Rhönlerche II, a single-seat, high-wing monoplane of mixed construction, built in 1962 by Flugzeugbau A. Schleicher (serial number 3001). Its certificate of airworthiness was valid from 19 June 1962 until 22 February 1965. At the time of the accident, the glider weighed approximately 300 kg, with its center of gravity within prescribed limits. No pre-existing airworthiness issues were identified.
The pilot, born in 1945, held a student pilot card for airplanes and gliders valid from 2 August 1963 to 30 May 1965. He began flight training in July 1963 at Granges airfield and passed the glider pilot license examination on 2 May 1964. To obtain the license, he still needed to complete three altitude-gain flights; the accident occurred during the second of these. His total training experience was 9 hours 38 minutes and 83 flights, all on the Rhönlerche II. There was no indication that the pilot was not in full possession of his faculties.
Accident Details
The accident occurred within the framework of a preparatory aeronautical training course organized by the Gliding Group of Granges. The instructor assigned the student a mission on 26 June 1964: a maximum flight duration of 75 minutes, an altitude gain of at least 30 minutes, a return to the airfield at an altitude of at least 600 m above the aerodrome, and a minimum airspeed of 78 km/h due to turbulence.
The student departed Granges airfield at 1158 HEC in glider HB-721. At 1305, he was flying along the Jura mountain range with the slope on his left in the region of Bettlachstock. During the previous six minutes, the glider had descended approximately 120 m. The pilot then initiated a right turn to reverse direction and resume slope flight. The airspeed was 78 km/h, the bank angle was 45°, and the ascents were irregular, averaging 1.0 m/s. The pilot held the turn too long and could not avoid the trees; the glider fell into the forest at 1315.
Damage
The pilot sustained no injury. The glider was destroyed to 80%. Damage to the terrain was insignificant.
Findings and Conclusion
The instructor's orders were appropriate for the student's training level and the mission. The weak ascents suggested that the student was flying close to the slope. However, if he had monitored his position relative to the slope, the collision could have been avoided without difficulty.
The accident was due to the inattention of the student pilot, who, while turning in slope flight and not monitoring his position, interrupted the turn late and suddenly found himself in a situation where collision with the slope was inevitable.