Colisión entre helicóptero Bell 47 G3 y planeador B-4 cerca del paso Sanetsch resulta en tres muertes
El 15 de julio de 1978, a las 12:25, un helicóptero y un planeador colisionaron frontalmente a aproximadamente 3 km al norte-noroeste del paso de Sanetsch. El helicóptero HB-XFA despegó de Gruyères a las 11:55, mientras que el planeador HB-1259 partió de Saanen a las 10:50. Ambos pilotos y la pasajera del helicóptero fallecieron, y las aeronaves fueron completamente destruidas. La investigación reveló que los pilotos no vieron el otro aeronave a tiempo, lo que llevó al accidente. Se recomienda mejorar la visibilidad y la conciencia situacional de los pilotos en estos espacios aéreos.
- Aerotow to cruise: The glider HB-1259 was aerotowed from Saanen at 10:50 and released after about five minutes near the south slope of Eggli to begin an alpine soaring flight.
- High-traffic glider zone: The flight took place within an active alpine glider zone near Sanetschpass, designated as a danger area with concentrated soaring activity.
- Poor mutual visibility: Flight tests later showed that a B-4 glider is very hard to see from a Bell 47 and that the helicopter is not audible from the glider, making see-and-avoid difficult.
- Converging flight paths: Around 12:25 the glider, circling north-northwest of Sanetschpass, and the helicopter flying toward Valais approached each other on nearly opposite headings at similar altitude without visual acquisition.
- No effective avoidance: Neither pilot initiated an avoidance maneuver, indicating that the opposing aircraft was not seen in time to react.
- Rotor strikes glider: The helicopter’s main rotor disc intersected the glider’s fuselage at about a 55° bank angle, cutting the B-4 longitudinally through the cockpit and right wing root and fatally striking the glider pilot.
- Crash - fatal: Both the disintegrated glider and the damaged helicopter fell onto the snow-covered scree slope at Lapi di Bou NNW of Sanetschpass, destroying both aircraft and killing all three occupants.