Colisión del Ka 8 B con un árbol durante el aterrizaje cerca de Les Pres Vaillons, Suiza
El 28 de mayo de 1976, un planeador Alexander Schleicher K 8 B colisionó con un árbol durante un intento de aterrizaje cerca de Les Pres Vaillons, Suiza. El piloto, que intentaba completar un vuelo de 75 km hacia Courtelary, se desorientó y entró en un valle estrecho. A pesar de la presencia de áreas de aterrizaje adecuadas anteriormente en el vuelo, el piloto continuó hasta que ocurrió la colisión. El planeador fue destruido y el piloto resultó herido. El informe oficial cita un conocimiento geográfico y de navegación insuficiente como factores contribuyentes.
- Cross-country cruise: After an aerotow departure from Fricktal-Schupfart, the pilot cruised along the Jura ridge toward his 75 km goal at Courtelary.
- Navigation error: Near the Taubenlochschlucht, the pilot misnavigated toward Courtelary by following what he thought was the correct valley, using an inadequately folded 1:200,000 map and then the 1:500,000 ICAO chart.
- Poor map setup: The topographic map was folded so that the Bielersee and the accident area were not visible, forcing reliance on a small-scale ICAO chart and rough valley counting.
- Delayed outlanding decision: Despite being in an area with suitable outlanding fields, the pilot continued toward the presumed goal instead of committing to an outlanding by 500 m AGL as recommended.
- Continued into narrow valley: The pilot flew in low level into the valley between Mont Sujet and the south flank of Chasseral, passing a last suitable pasture near Métairie de Prêles without attempting to land.
- Trapped low in valley: At low height above the terrain, the pilot attempted to turn but, due to the narrow valley and insufficient altitude, rolled out and continued just above the treetops down the descending valley.
- Crash - minor injury: About 1.3 km beyond the pass, the right wingtip struck the top of a fir tree, the glider overturned into a near-vertical crash, destroying the aircraft and injuring the pilot.