Collision de Standard Libelle avec des lignes électriques lors d'un atterrissage en campagne près de Weesen, Suisse

Le 20 avril 1974, un planeur Glasflügel Standard Libelle a heurté des lignes électriques lors d'un atterrissage en campagne près de Weesen, en Suisse. Le pilote, participant à un camp d'entraînement, a rencontré de fortes descendances lors de l'approche finale, entraînant un atterrissage imprévu. Malgré les conditions difficiles, le pilote est resté indemne, bien que le planeur ait subi des dommages importants. La collision s'est produite dans une zone avec plusieurs lignes électriques, et l'éblouissement du soleil a probablement obscurci la vue du pilote sur les câbles haute tension.

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.