What happened
On July 5, 1964, a student pilot was conducting a solo flight exercise at the newly opened Winterthur-Hegmatmen airfield. Following a successful instructional check flight performed by a flight instructor in the same aircraft, the student took off in the Rhönlerche II, registration HB-708, at 14:51 local time. After completing several full circles southwest of Wiesendangen, the pilot returned to the airfield and descended to approximately 100 meters above ground level at the prescribed turning point. During the final approach, the aircraft encountered a downdraft while flying over a gravel pit located at the extension of the runway. The loss of altitude prevented the pilot from reaching the airfield, forcing an emergency landing in the gravel pit. The aircraft struck a gravel bank and collided with the edge of the pit, resulting in no injuries to the pilot but causing significant damage to the airframe.
The investigation
The investigation examined the flight sequence, the pilot's experience, and the environmental conditions at the time of the accident. The pilot was a student with approximately 16 hours of total flight time, a portion of which was logged in the Rhönlerche II. Investigators noted that the flight was only the student's second time operating at the Winterthur-Hegmatten airfield. Weather conditions were characterized by light, variable winds and the presence of thermic activity. The investigation focused on the pilot's altitude management during the approach and the impact of the wind conditions on the flight path.
Findings
- The pilot descended to 100 meters during the approach, which was at the lower limit required to maintain a safe margin for a standard landing.
- An error in altitude estimation occurred during the transition to the final approach.
- The aircraft encountered an unexpected downdraft during the final stage of the approach.
- The combination of low altitude and the sudden loss of lift made it impossible to reach the runway, necessitating an off-field landing in unfavorable terrain.
Safety action
No specific safety recommendations were recorded in the final report.