What happened
On May 10, 2017, at approximately 09:33 UTC, a Westland-Bell 47G-3B-1 helicopter departed from Innsbruck Airport for a private VFR flight. The flight path took the aircraft through the Inn Valley and into the Gerntal and Falzthurntal valleys.
While flying near the Gramaialm alpine inn, the helicopter struck the haul rope of the Gramaialm material cableway at an altitude of approximately 75 m AGL. The impact caused a massive, sudden deceleration, which resulted in the right saddle tank breaking free from its mounts and bursting. The unbelted passenger was thrown forward through the cockpit glazing. The aircraft pitched forward over the cable, tumbled, and struck the ground, immediately catching fire. The pilot and passenger both sustained fatal injuries.
The investigation
The SUB investigation reconstructed the flight path using eyewitness accounts, radar data, and GPS records. Investigators examined the aircraft's maintenance history, weight and balance, and the status of the cableway. The investigation also reviewed meteorological conditions and the pilot's flight preparation materials found at the wreckage site.
Findings
- The primary cause of the accident was controlled flight into terrain (CFIT), specifically a collision with the cableway's haul rope.
- The pilot was flying below the minimum required altitude.
- The aircraft was operating without an obstacle warning system or a cable avoidance system, neither of which are available for this specific model.
- The cableway was a permanent, approved obstacle correctly listed in the Austrian AIP and ICAO charts.
- The aircraft was in a technically sound condition, and all maintenance was up to date.
- The pilot's health was not a contributing factor, and weather conditions were not a cause of the accident.
- The passenger was not wearing a seatbelt at the time of the impact.