Standard Libelle collision with power lines during outlanding near Weesen, Switzerland

On April 20, 1974, a Glasflügel Standard Libelle experienced a collision with power lines while attempting an outlanding near Weesen, Switzerland. The pilot, participating in a training camp, encountered strong downdrafts during the final approach, leading to an unplanned landing. Despite the challenging conditions, the pilot was unharmed, although the glider sustained significant damage. The collision occurred in an area with multiple electrical lines, and the incident was exacerbated by the sun's glare, which likely obscured the pilot's view of the high-voltage cables.

1. Cross-country cruise: During a training camp triangle task from Schänis, the pilot was on final cross-country leg toward Schänis with an end-of-flight altitude reserve of about 400 m.
2. Strong lake downdrafts: Over the western half of Lake Walen, the glider encountered extensive downdraft areas with sink rates up to 6 m/s, rapidly eroding the planned altitude reserve.
3. Low final reserve: The pilot’s end-of-flight plan included only a modest 400 m height reserve, which proved insufficient in the unexpectedly strong sink near the end of the task.
4. Decision to outland: Unable to reach Schänis due to the unexpected altitude loss, the pilot selected a field near Süstli for an outlanding in an area crossed by several power lines.
5. Sun glare on approach: On final approach in backlighting with low sun, the pilot was likely blinded by the sun and did not perceive the unmarked 16 kV power line ahead.
6. Collision with power lines: On landing approach the glider’s left wing struck and severed the grounding cable of a 16 kV line, then the right wing hit and tore several wires of a 380 V line, leaving the aircraft hanging partially supported by the wires.
7. Outlanding - damage: The glider came to rest about 4 m above ground with significant structural damage, but the pilot was uninjured and exited after reporting the accident by radio.