LAX99TA299 · Bell B212

While engaged in fire fighting water-dropping operations, the helicopter impacted high tension power transmission wires and fell to the ground under marginal control. The pilot and helicopter were reassigned from another nearby base on the morning of the accident and, at the time of the wire strike, the pilot was engaged in his first operational sortie in the new area. Prior to takeoff the pilot had been briefed about wire hazards in the area. A topographical map that was used in the briefing showed high power transmission wires, including the set the pilot later impacted, as red lines. After takeoff, the pilot proceeded to the fire area and made an initial drop on the fire. It was while returning to the dip site to refill that the wire strike occurred. The pilot reported that as he approached the dip site at 250 - 300 feet agl, he was aware of a power transmission tower high on the mountain to his right, well above him. He was also aware of another tower to his left on the valley floor below and an electrical powerhouse on the valley floor nearly in front of him. He thought that the wires from both the tower on his right and the tower on his left went to the powerhouse and were beneath him. In fact, the wires were strung directly from the tower above him, on the right, to the lower tower, on his left, and crossed his flight path at the helicopter's altitude. Visual meteorological conditions prevailed and smoke was not present in the area of the accident. Flights flown after the accident in like conditions of daylight and visibility showed the wires could not be visually detected until the helicopter was 'extremely close to the wires.'

Verbatim NTSB analysis and probable cause from the NTSB dataset