What happened
On 9 December 1956, Flight 810-9 departed Vancouver at 18:10 PST, bound for Toronto. The flight, operated by a crew of 3 and carrying 59 passengers, was cleared to fly toward Calgary Airport via several waypoints including Mud Bay, Abbotsford, and Cultus Lake. During the cruise at 19,000 feet, the crew reported encountering icing starting at 16,000 feet, followed by moderate turbulence. At 18:48, the flight requested an increase in altitude to 21,000 feet.
At 18:52, the crew notified Air Traffic Control of a fire in the number two engine and confirmed that the engine had been shut down. The aircraft began an emergency return to Vancouver. Following this, the pilot reported difficulty maintaining the current altitude and requested permission to descend. The final altitude reported was slightly above 15,000 feet. At 19:10, the flight reported passing Hope and requested a descent to 10,000 feet; controllers instructed the aircraft to maintain at least 8,000 feet while crossing the Vancouver range. This was the final communication received from the aircraft.
The wreckage was not located until 12 May 1957, when climbers discovered debris on Mt Slesse at an elevation of approximately 7,600 feet.
Findings
Investigations into the crash of the unspecified aircraft type involved several contributing factors. The crew had experienced a loss of power due to the shutdown of the number two engine following a suspected fire. Additionally, the area was known to contain severe turbulence, moderate to severe icing, and subsidence. Investigators concluded that the aircraft likely encountered extreme weather conditions or sudden mechanical failure so severe that the crew could not maintain control or communicate with controllers. The aircraft also deviated from its assigned Green Airway No. 1 during the descent.
The accident resulted in 62 fatalities.