What happened
On May 28, 1976, a K 8 B glider, registration HB-668, departed from the Fricktal-Schupfart airfield for a cross-country flight. The pilot's objective was to complete a 50 km route to earn a silver performance badge, selecting Courtelary as the destination. After utilizing thermal currents along the Jura ridge, the pilot began a descent toward the target area.
During the descent, the pilot became disoriented. While navigating the Taubenloch Gorge, the pilot found that a folded 1:200,000 scale topographic map obscured vital landmarks, such as Lake Biel. This forced a reliance on a larger-scale 1:500,000 ICAO chart, which proved insufficient for precise navigation. The pilot attempted to locate the airfield by counting valleys, eventually entering a narrow valley between Mont Sujet and the Chasseralsüd flank at a dangerously low altitude.
As the aircraft followed the descending valley floor, the pilot failed to utilize an available landing field on a pasture near the Métairie de Prêles. While attempting a turn at low altitude, the right wing struck the top of a fir tree. The impact caused the aircraft to capsize into an inverted position, resulting in a vertical plunge and the death of the pilot.
The investigation
Investigators examined the wreckage and recovered a Swiss road map containing handwritten flight planning notes, including a planned glide path and target altitude. The investigation confirmed that the aircraft was airworthy, with weight and balance within limits, and found no evidence of mechanical failure.
Radio communications were also reviewed; a pilot in the Barmelweid area had contacted the crew to coordinate a recovery, noting that the pilot of HB-668 had reported being near the north end of Lake Biel before later reporting proximity to Courtelary.
Findings
- The pilot's navigational knowledge and geographical awareness were insufficient for the task.
- The use of a 1:200,000 scale map, folded in a way that obscured key landmarks, hindered effective navigation.
- The pilot demonstrated a lack of decisiveness by continuing the flight toward the destination despite being lost, rather than executing an outlanding when altitude permitted.
- The pilot failed to adhere to safety guidelines requiring a landing decision to be made no lower than 500 meters above ground level.