Flight Purpose
The helicopter was transporting railroad officials to inspect rail lines that had been covered by mudslides caused by recent heavy rains.
Witness Account
A witness reported hearing the helicopter approaching up the valley, followed by two popping sounds. The witness then observed the helicopter falling to the ground in the vicinity of power lines that were strung across the valley above the railroad tracks.
Power Line Details
The power line assembly consisted of two static lines at the top and three power lines at the bottom. After the incident, the uppermost static line was found separated and lying on the lower static line. The lines were approximately 300 feet above ground level and were unmarked.
Pilot Familiarity
The pilot was familiar with the operating area and purportedly aware of the location of the power lines.