Introduction
On [date not specified], a helicopter conducting aerial photography for Canadian National Railway (CN) struck two steel electrical wires while flying at low level over a moving train near Hinton, Alberta. The accident resulted in serious injuries to one occupant and minor injuries to two others, including the pilot.
The Flight
The pilot and two film crew members were filming CN train traffic from a helicopter. After a briefing at the Canadian Helicopters Limited facility at Edmonton City Centre Airport, the crew departed for the filming area. The pilot was cautioned by a CN representative to avoid low overflight that could startle the train crew. The film director requested the lowest and fastest flight consistent with safety.
The helicopter was equipped with a Tyler 206 Nose Mount II camera system. The camera operator sat in the left front seat, the film director in the right rear seat. The pilot occupied the right front seat and wore a helmet. The helicopter was not fitted with a wire strike protection system.
The Accident
At about 1610 Mountain Standard Time, the helicopter was making a low pass over the train. The pilot descended to a skid height of approximately 12 feet above the rail cars. About 30 seconds into the run, the helicopter struck two steel electrical wires that crossed the tracks at a 90-degree angle. The wires contacted the helicopter just above the windshield and moved aft into the pitch control rods and main rotor mast, severing the control rods. The helicopter pitched up, yawed left and right, then descended in a 45-degree nose-down attitude, striking the ground about 90 feet left of the train and 600 feet beyond the wire strike point.
Injuries and Damage
All occupants were wearing lap and shoulder harnesses; the pilot also wore a helmet. The left front seat passenger (cameraman) sustained serious injuries, while the pilot and the right rear passenger (film director) received minor injuries. The helicopter was substantially damaged. The pilot's left lap belt failed during impact; testing showed the belt no longer met the required tensile strength of 2,250 pounds, likely due to long-term sunlight exposure.
Findings and Causes
According to the Transportation Safety Board (TSB) investigation, the pilot lost control when the pitch control rods failed following the wire strike. A contributing factor was that the pilot did not conduct a reconnaissance of the final flight path to check for obstacles. The helicopter was not equipped with a wire strike protection system, which might have cut the wires upon contact. The TSB also noted that the pilot had been cautioned about low overflight and had discussed hazards with the company chief pilot before the operation.