Ka 7 collision with telephone line near Diavolezza injures two

On August 18, 1962, an Alexander Schleicher Ka 7 glider collided with a telephone line near Diavolezza, Switzerland. The glider, carrying a pilot and his father as a passenger, was attempting to gain altitude when it made contact with the line. The aircraft subsequently crashed into rocks and overturned, causing severe injuries to both occupants. The glider was completely destroyed in the incident. The official investigation confirmed that the collision with the telephone line was the primary cause of the accident.

1. Soaring along ridge: After a winch launch from Samedan, the Ka-7 spent about 2.5 hours soaring in the Oberengadin and was ridge-soaring near Munt Pers before returning toward the airfield.
2. Low ridge clearance: While following the ridge from Munt Pers toward the Diavolezza hut, the pilot flew past the hut with an estimated clearance of only about 25 m above the slope and 40 m from the hut.
3. Altitude lost in turn: The pilot then turned right toward Piz Palü and executed a wide, high-banked right turn of about 200 degrees over the Pers glacier margin, during which the glider visibly lost height.
4. Return low to slope: About 80 m below hut level, the pilot approached the same slope again at a shallow angle, closely following the contour lines to remain near expected lift, thereby reducing terrain and obstacle clearance.
5. Poor obstacle visibility: In the shallow, uniform scree slope with weak relief, the telephone line—spanning 15–23 m above ground and lacking nearby masts or markers—was difficult to perceive against the background.
6. Collision with cable: While turning slightly left to fly parallel to the slope, the glider struck the two-wire telephone line at about 60 degrees, damaging the canopy and left wing and causing a significant deceleration and left yaw.
7. Crash - serious injury: Approximately 60 m after first contacting the line, the glider impacted a rock band in a steep attitude, overturned, and came to rest inverted, totally destroying the aircraft and seriously injuring both pilot and passenger.