What happened
On June 27, 1964, a student pilot was conducting a solo gliding flight in a Grunau-Baby II, registration HB-120, near the Lausanne-Blécherette airfield. The flight was part of a requirement to complete a 30-minute duration for a glider pilot license examination. After nearly an hour of flight, the pilot began an approach following local procedures, which involved crossing the runway threshold perpendicularly and executing three 90-degree left turns to align with the landing strip.
During the second turn, the pilot realized the aircraft was too low to clear a line of trees obstructing the approach path to the airfield. Forced to abandon the planned landing at Blécherette, the pilot identified a potato field at "La Vallombreuse" as a potential emergency landing site. However, because this terrain was approximately 50 meters lower than the airfield plateau, the pilot found himself at an altitude of only 25 to 30 meters. Attempting to execute the necessary turns to align with the new landing direction, the left wing of the glider struck the ground during the third turn, causing the aircraft to pivot and crash.
The investigation
Investigators examined the pilot's experience, noting that while the pilot had approximately 20 hours of total flight time, they had only 64 minutes of experience specifically on the Grunau-Baby II type. The investigation also reviewed the meteorological conditions, which were warm and cloudy with a 10-knot northeast wind, and the topographical differences between the Lausanne airfield plateau and the surrounding terrain.
Findings
- The pilot made an error in judgment regarding the approach pattern, failing to properly adapt the maneuver to the 10-knot northeast wind.
- The pilot remained in a tailwind position for too long, which eventually led to the obstruction by trees.
- The significant difference in elevation between the airfield plateau and the lower terrain likely caused a miscalculation of altitude.
- The emergency landing was attempted at an insufficient altitude to complete the required turning maneuvers, leading to the wing strike.