Accidente de K 7 durante remolque aéreo en Melchtal resulta en lesiones graves

El 2 de agosto de 1969, un planeador K 7 sufrió un accidente durante un remolque aéreo cerca de Melchtal, Suiza. El planeador, que llevaba a un piloto y un pasajero, era remolcado por una aeronave motorizada cuando encontró turbulencias y corrientes descendentes. La cuerda de remolque se rompió a baja altitud, y el planeador intentó un aterrizaje de emergencia con la cuerda aún sujeta. El aterrizaje falló, resultando en el choque del planeador y lesiones graves para ambos ocupantes. El planeador fue destruido, pero no hubo víctimas fatales.

1. Aerotow into valley: The K 7 glider with pilot and passenger was aerotowed from Sarnen-Kägiswil into the Melchtal, climbing along the valley flanks to use expected updrafts.
2. Low entry altitude: The tow entered the Melchtal at a relatively low height above terrain compared with local recommendations, leaving limited safety margin in the narrow valley.
3. Downdrafts and turbulence: After initial climb in weak lift, the tow encountered zones of downdraft around 3–6 m/s and strong turbulence, causing frequent towrope slack and altitude loss.
4. Towrope weak link breaks: Shortly after a steep 180° turn near the village of Melchtal, the front 540 kg weak link on the 60 m towrope failed following a rope slack and re-tension event at low height.
5. Emergency landing attempt: With the rope still attached, the glider pilot initiated a right turn toward the right valley flank to attempt an uphill emergency landing on a selected field, reportedly operating the release handle but not shedding the rope.
6. Rope contacts power line: During the low-altitude maneuvering, the slack towrope hung from the glider and contacted the lower 9 kV power line, abruptly pulling the glider toward the slope and into a steep descending right turn.
7. Crash - serious injury: The glider impacted the valley slope in a steep right turn, overturned, and was destroyed, with both occupants sustaining serious injuries.