Summary
The accident occurred on 15 July 1962 during a mission to deliver fuel for a rescue operation.
Flight Sequence
The pilot took off from Kloten at 1720 hours with six packages, each containing two 5-liter plastic canisters tied together and attached to a parachute. He arrived at Disentis shortly after 18:00. The first airdrop failed when the canisters separated from the parachute and shattered on the ground. The second parachute drifted 500 meters from the target into a gully. Subsequently, the pilot decided to land on a triangular meadow approximately 220 meters long, with a tailwind uphill. Approaching too high, he applied full throttle to abort the landing. After several hundred meters of flight at full power, the aircraft touched down on an ascending meadow. The left wheel struck a boundary stone. The aircraft rolled toward the gorge of the Vorderrhein, became airborne, and collided with the lightning protection cable of a high-tension line around 1335 hours. The aircraft crashed, caught fire, and was destroyed. The pilot remained in the flames.
Aircraft and Pilot
The aircraft was a Piper Super Cub PA-18, registration HB-OPX, built in 1957, powered by a Lycoming O-320 150 hp engine. It had accumulated 1215 total hours. Its maximum takeoff weight was 794 kg; at takeoff it weighed 820 kg, exceeding the limit, and at the time of the accident it weighed 765 kg. The center of gravity was within limits. The pilot, born 1919, held a private pilot license since 1947 and a restricted professional pilot license since 1960. He had a total of 354.75 hours on fixed-wing aircraft and 63 hours on helicopters. His experience on Piper Super Cubs was limited to mostly takeoff and landing training, totaling 22.5 hours over four years, with an average flight duration of 3.75 minutes. He had attended a one-day airdrop course in 1960 and performed two practice drops. No additional airdrop training or missions followed until the accident.
Terrain and Weather
The accident site was a plateau southeast of Disentis, sloping about 8% from east to west. The triangular meadow used for landing was about 220 meters long, flanked by a deep stream gully and a road with barns. A high-tension line crossed the south edge, with a thin lightning protection cable at the top of the masts. The visibility was 50 km with scattered cumulus clouds up to 3200 meters. The wind was from the northeast at about 10 knots, with expected crosswind gusts from the northwest later in the afternoon.
Organizational and Regulatory Context
The mission was conducted under the Swiss Rescue Flight Service (SRFW). According to regulations, the dropping of objects is prohibited except for rescue operations, and special permits apply. The pilot held the required professional pilot license.