A helicopter crash that killed three men in northern B.C. in July 2011 was likely caused when the main rotor blades struck the side of a mountain, say Canada's Transportation Safety Board.Approximate location of the crash site
The wreckage of the helicopter and the remains of the pilot and two passengers were found on the side of a mountain 26 kilometres north of Stewart, adjacent to the Nelson Glacier, approximately six hours after the crash.
All three victims were performing geological work for a mining company at the time of the crash.
In a written statement, the TSB said, "The investigation concluded that while working in close proximity to steep terrain, the helicopter's main rotor blades made contact with terrain, causing loss of control; it then crashed.
"Investigators determined that the accident was not survivable."
The TSB says it made its assessment based on the condition of the wreckage, data from a GPS unit, data from cameras held by the occupants, and information from data chips on engine components.
Data from an electronic control unit recovered showed that the main-rotor rpm suddenly dropped after the helicopter had been in, or near, a stationary hover.
"It is likely that the decrease in main-rotor speed occurred as a result of the main-rotor blades making contact with an obstacle as the helicopter manoeuvred in close proximity to the rock face," the report said.
The helicopter was operated by Vancouver Island Helicopters, and the TSB noted in its report that procedures regarding filing flight plans and tracking overdue aircraft were not followed.
The company did not have a time-based check-in call plan for the trip. When the GPS signal from the helicopter went dead near the planned drop-off location, ground personnel did not know for some time that the helicopter had crashed.
The TSB report says crews assumed that the pilot had landed and shut down, perhaps to wait out poor weather.
"When a company's actual practice does not follow its written procedure, flight crew and passengers may be at increased risk of injury or death following an accident," the TSB said in a written statement.
"As a result of the accident, VIH Helicopters Ltd. is working with manufacturers of flight data monitoring systems to develop and test hardware and software that would further meet the needs of visual flight rules helicopter operations."