What happened
On September 8, 1973, a student pilot was conducting training flights at the Fricktal-Schupfart airfield. Following a successful solo flight earlier in the afternoon, the pilot commenced a second solo flight at 17:58. The flight mission, prescribed by the instructor, involved a specific sequence of maneuvers including figure-eights and turns. While the flight proceeded normally through most stages, the pilot deviated slightly from the instructions by performing four full turns instead of the requested three.
During the final approach, at an altitude of approximately 90 meters, the Rhönlerlyche II entered a steep dive. The aircraft subsequently transitioned into an inverted flight position. After an attempt at an inverted climb, the glider banked sharply to the right, struck two trees, and impacted the ground approximately 300 meters east of runway 26. The impact resulted in the destruction of the aircraft and serious injuries to the pilot.
The investigation
Investigators examined the flight records, the aircraft's technical status, and witness accounts. The pilot, who had approximately nine hours of total flight experience, was unable to recall the sequence of events due to retrograde amnesia following the accident. Technical inspections of the HB-623 confirmed the glider was airworthy and that its weight and center of gravity were within permissible limits at the time of the accident.
Witnesses at the airfield observed the aircraft's rapid transition from a dive into an inverted state. Furthermore, flight testing conducted with a similar Rhönlerche II demonstrated that the aircraft's control surfaces are sensitive enough that minimal physical force on the control stick could induce a dive or even an inverted position.
Findings
- The aircraft was mechanically sound with no evidence of pre-existing technical defects.
- The flight training program and the specific mission assigned were appropriate for the pilot's skill level.
- The primary cause of the uncontrolled flight attitude was a loss of consciousness experienced by the pilot during the final approach.