What happened
On August 19, 1964, a Rhönlerche II glider, registration HB-672, was performing a training flight at Amlikon airfield as part of a pre-training course. The flight was part of a series of maneuvers intended to practice a left-hand side-slip approach.
During the final approach, the pilot successfully initiated the side-slip, but the aircraft drifted slightly to the left. As the pilot attempted to straighten the aircraft and recover from the slip, the glider began to yaw sharply to the right. The aircraft drifted perpendicularly away from the runway axis, crossing over the nearby Thur river. The flight path suggested a subsequent attempt to execute a right-hand turn to return to the airfield, but the aircraft ultimately struck the ground with a heavy longitudinal and lateral tilt. The impact caused the right wing to break off and resulted in significant structural damage to the fuselage and canopy.
The investigation
Investigators examined the aircraft, the pilot's training records, and the environmental conditions at the time of the accident. The pilot, a student with approximately seven hours of total flight time, had been performing well in his course, though his instructor noted he was experiencing a period of inconsistent performance. The investigation found no evidence of medical issues affecting the pilot's ability to fly.
Technical inspections of the Rhönlerche II revealed no mechanical defects or structural failures that could have contributed to the accident. The aircraft's weight and center of gravity were within limits. The investigation also considered the weather, noting that while the area was experiencing wind and potential turbulence due to nearby terrain, the exact influence of these factors could not be definitively determined.
Findings
- The primary cause of the accident was a pilot error involving the loss of control following the recovery from a side-slip.
- The student pilot was unable to effectively coordinate lateral and directional control inputs after straightening the aircraft from the left-hand slip.
- The pilot likely became disoriented by the unexpected flight path, leading to a loss of control that resulted in the aircraft veering perpendicularly from the runway.
- The pilot sustained minor injuries to the face, while the glider sustained approximately 70% damage.