What happened
On September 6, 1969, a Cessna 150 (registration HB-CSF) was participating in the Swiss Motor Flying Championships. The flight was a navigation leg of the reliability championship, intended to fly from Altenrhein to Friedrichshafen and back to Altenrhein via several waypoints.
After departing Altenrhein, the crew flew toward Friedrichshafen and then proceeded toward the waypoint ALFA near Amriswil. During this segment, the pilot increased the altitude to between 3,000 and 3,500 feet. This maneuver caused the aircraft to enter patches of fog and mist, which significantly reduced visibility. As the crew attempted to navigate toward Arbon and return to Altenrhein, they became disoriented due to the deteriorating weather conditions.
Unable to identify landmarks and unable to establish radio contact with Altenrhein, the crew circled the Teufen area for approximately 15 minutes. Seeking a way out of the fog, they identified a flat plateau and decided to perform an emergency landing on a meadow. During the final approach, the pilot noticed grazing cattle on the field and adjusted the landing axis to the right. While the aircraft initially touched down normally, the crew had underestimated the slope of the terrain. The impact against the rising ground caused the nose gear to collapse, bringing the aircraft to an immediate halt.
The investigation
The investigation examined the flight crew's experience, the aircraft's maintenance history, and the meteorological conditions at the time of the accident. Investigators reviewed the flight logs, which showed the pilot had significant experience on the type, and confirmed the aircraft was properly maintained and airworthy. The investigation also looked into the decision-making process regarding the flight altitude and the choice of landing site.