Accident Overview
On 19 August 1964 at 16:51 MEZ, a Rhönlerche II glider, registration HB-672, crashed on the grass runway 28 of Amlikon airfield in the canton of Thurgau, Switzerland. The aircraft was operated by Segelfluggruppe Cumulus and was being used for a flight training course (FVS course S25) for student pilots. The pilot, a 19-year-old flight student, sustained minor injuries (facial cuts) and was treated at Kantonsspital Frauenfeld before being released. The glider was destroyed to about 70% of its value.
Aircraft and Pilot Information
The aircraft was a Rhönlerche II, a two-seat high-wing glider of mixed construction, manufactured by Schleicher of Poppenhausen, Germany (works number 798, built 1960). It had a maximum takeoff weight of 400 kg; at the time of the accident, the weight was approximately 290 kg, with the center of gravity within limits. The total time on the airframe was 763 flight hours and 5,976 landings. No technical defects were found during the wreckage investigation.
The pilot held a student glider license issued on 20 November 1963, valid until 10 September 1965. He had begun his training on 19 April 1964 at Amlikon and had accumulated 7 hours and 17 minutes of flight time with 59 landings, all on HB-672. In his first course, he was rated well qualified, but during the second course (starting 17 August 1964), his performance dropped to average due to a known learning plateau. The flight instructor, born 1930, held a glider instructor authorization since 23 September 1957.
Accident Sequence
The accident flight began with a tow launch at 16:42 MEZ. After release at about 400 meters, the pilot performed right and left full circles, then began a final approach with a left glissade. The instructor, observing from the runway, noted that the glissade initially appeared stable but then broke slightly left. The pilot corrected, bringing the glider back to the left of the runway axis at approximately 30 meters height and 200 meters from the landing strip. As the pilot raised the glider from the glissade, the longitudinal pitch decreased, and the aircraft yawed to the right without changing bank. The glider departed the strip at a right angle, turned over the Thur River, and returned to the field, where it struck the ground with a pitch of 20–30 degrees and a bank, hitting nose-first. The right wing separated at the root, and the aircraft rotated 135 degrees clockwise before coming to rest about 20 meters from the initial impact. The instructor reported that the final phase appeared to be a flown curve, with pitch and bank increasing and maintained until impact. The pilot later recalled that after the glissade, he brought the glider back over the runway, but a subsequent left rudder input produced no response; he had no further memory.
Damage
The pilot suffered facial cuts but was treated as an outpatient. The glider was severely damaged: the right wing broke at the root, the fuselage was crumpled forward and bent between the wings and tail, and the plexiglass canopy shattered. The owner estimated repair costs at approximately 10,000 Swiss francs and decided to rebuild the aircraft. No ground damage occurred.
Discussion and Findings
The investigation concluded that the pilot, after raising from the glissade, failed to coordinate rudder and aileron controls, causing a temporary loss of control. The glider then veered right uncontrollably. The influence of wind and turbulence in the approach zone could not be determined. The pilot's actions during the final right turn may have been an attempt to return to the field, but no corrective inputs were observed before impact.