What happened
On August 6, 1973, an Elfe-Standard S/3 P glider, registration HB-858, was conducting a private cross-country flight as part of a glider instructor training course. After gaining altitude through thermal lift over the Jura mountains, the pilot encountered turbulence and downdrafts near Zeglingen. Due to the sinking conditions, the pilot decided to perform an outlanding on a mown field east of Wenslingen.
The landing area, measuring approximately 250 meters by 40 meters, was intersected by an electrical power line supported by 10-meter wooden poles. While approaching the field, the pilot began circling the landing site from an altitude of approximately 100 meters. During these maneuvers, the power lines passed beneath the flight path. As the pilot attempted a final 180-degree turn to align with the landing direction, the aircraft entered a steep bank. Approximately 50 meters before reaching the intended landing heading, the glider stalled at an altitude of about 10 meters, causing the left wing to drop and the aircraft to crash into a clover field. The accident resulted in one fatality and the total destruction of the aircraft.
The investigation
The investigation focused on the pilot's flight maneuvers and the environmental conditions at the time of the accident. The aircraft was found to be airworthy, with the weight and center of gravity within prescribed limits. No pre-existing mechanical defects were identified. The pilot was a qualified instructor with significant flight experience, and no health issues were noted as contributing factors. Weather conditions were characterized by scattered clouds at 1,000 meters and light westerly winds with occasional gusts.
Findings
- The pilot attempted a landing approach using a descending spiral from above the landing site rather than a standard, professional circuit.
- This specific approach pattern was unsuitable because it resulted in a low-altitude turn that brought the aircraft tangential to the overhead power lines.
- The primary cause of the accident was an unsuitable landing approach procedure combined with the aircraft's speed falling below the minimum required flight velocity.