1968 Bell 47G-2 Helicopter Accident Near Bern Airport (HB-XAX)

Accident Overview and Investigation Approval On 23 February 1968, a Bell 47G-2 helicopter with registration HB-XAX collided with a wooden utility pole while conducting a simulated spraying flight near Bern Airport. The Swiss Federal Accident Investigation Commission approved its final report on 9 and 25 September 1968, incorporating a supplemental item numbered 43. The aircraft was destroyed, while the two occupants escaped without injury. ## Aircraft and Occupants The helicopter was owned and operated by Heliswiss, Schweiz. Helikopter A.G., based in Bern. It was a Bell 47G-2 manufactured in 1958, with serial number 2195, powered by a Lycoming VO-435-A1D engine rated at 260 hp. The aircraft had a maximum allowable flight weight of 1,112 kg and weighed approximately 1,040 kg at the time of the accident, with the center of gravity within limits. No technical defects were found during the investigation. The flight instructor, born in 1919, held a commercial helicopter pilot license valid until 22 May 1968, with an entry for the accident aircraft type. He had 2,388 total helicopter hours, primarily on Bell 47 aircraft. The student pilot, born in 1945, held a private helicopter pilot license issued on 10 January 1968 and had 48 hours and 45 minutes of flight experience on Bell 47 aircraft. ## Sequence of Events The flight departed Bern Airport at 10:30 local time. The student pilot occupied the left seat and the instructor the right seat. The spraying equipment was not installed; instead, six 20-liter gasoline cans were distributed in the cargo nets on both sides of the fuselage to simulate the spraying load. After practicing over open, obstacle-free fields, the instructor increased the difficulty by selecting terrain with obstacles. While flying along an overhead power line that made a right-angle turn to the left, the instructor attempted to demonstrate how to fly such a corner. During the left turn at approximately 1 meter above the ground, the helicopter approached the row of poles too closely and the rotor struck wooden pole 2/64 belonging to the Belp Electricity Administration. The rotor blades shattered and the pole broke. The aircraft, rendered inoperable, made a hard landing in normal attitude. The flexible steel rods of the rotor blades struck the lattice fuselage, the rotor shaft broke free from its bearing, and the rotor head tipped forward through the Plexiglas cockpit canopy without striking the occupants. ## Damage and Contributing Factors Both occupants were uninjured. The helicopter sustained 100% damage. The power line itself was undamaged except for the replaced wooden pole, and no third-party damage occurred. The investigation found that the accident occurred during an instructor demonstration, with the student pilot at the dual controls but not influencing the maneuver. Weather conditions were clear of precipitation, the air was calm, and visibility was good. The instructor had extensive experience in aerial work and was in good condition. The collision was attributed to the pilot likely selecting too narrow a distance from the obstacles and then contacting the pole due to inattention or misjudgment.