Accident Summary
On 18 June 1964, at approximately 1040 hours, a Bell 47-G2 helicopter, registration HB-XAT, struck a steel cable shortly after takeoff from a makeshift helipad at Unterer Lauchbühl, above Grindelwald, Switzerland. The helicopter was owned by Heliswiss A.G., Bern. The pilot, born in 1931, held a commercial helicopter pilot license issued on 11 December 1963 and had 91 hours 25 minutes of helicopter flight experience with 1322 landings. He was also a motor flight instructor and commercial pilot. This was his first independent transport mission for Heliswiss.
Sequence of Events
On the evening of 17 June, the pilot received a call from Heliswiss to perform urgent material transport and passenger flights on 18 June. The base station was provided the next morning by a secretary. On 18 June, the pilot departed from Bern and landed at the designated landing site at 1035. The site was marked with a white cloth, and the ground crew had not yet arrived. To save time, the pilot loaded the cargo himself. At 1040, he initiated a vertical takeoff to about 1 meter, then turned approximately 90° left to transition into forward flight downhill. Suddenly, he spotted a steel cable stretching diagonally from the ground to a low roof about 15 meters away. Before he could react, the helicopter collided with the cable, shattering the plexiglass cabin. The pilot pushed the cyclic forward to increase speed, breaking the cable. The cable then wrapped around the rotor axis, but the pilot successfully landed the helicopter on a small hill about 40 meters away without further damage.
Damage
No personal injuries occurred. The helicopter sustained damage including shattered plexiglass, both main rotor blades unrepairable, and various control transmission damage. Estimated repair costs were approximately 25,000 Swiss Francs (10-15% of the helicopter's value). The ground damage consisted of a severed steel cable approximately 1 cm in diameter.
Discussion and Conclusion
The investigation concluded that the accident was caused by the pilot flying into a flatly stretched wire cable about 15 meters after takeoff and just above the ground, which he had not noticed. The pilot had not conducted a thorough inspection of the takeoff area, possibly due to time pressure and distraction from loading the helicopter.