Investigation Summary
The flight was operating in a complex weather system known as a trowal (trough of warm air aloft), which produced severe icing and heavy turbulence. At 18:52 PST, the crew reported a fire in the number 2 (inner port) engine. Although the North Star was known for false fire warnings, the crew followed protocol, shut down the engine, and feathered the propeller. While the pilots requested a return to Vancouver via Airway Green 1, which offered the most favorable terrain for an aircraft losing altitude, they inexplicably turned right instead of left. This maneuver placed them south of the safe corridor and directly over the rugged Border Peaks. Radar data from a U.S. station at Birch Bay tracked the aircraft until it disappeared near Mount Silvertip, just moments before impacting the vertical face of Mount Slesse at approximately 7,600 feet.
Final Conclusions
The official investigation concluded that the aircraft was at an insufficient altitude to clear Mount Slesse due to a combination of flying on three engines, severe icing, and subsidence (downward air currents). The report noted that for undetermined reasons, the aircraft was not on the cleared Green Airway 1. The loss of the number 2 engine and the existence of severe turbulence were cited as major contributing factors.
Video Analysis
No video analysis linked for this case file yet.
Airframe & Maintenance
Systems & Failure Modes
Rolls-Royce Merlin 622 Engines
The aircraft was powered by four liquid-cooled Merlin engines, which were significantly louder than the radial engines typically used on DC-4s.
Fire Warning System
A suspected false fire warning led to the shutdown of the No. 2 engine, initiating the emergency return.
Spirit Compasses
Magnetic navigation instruments that should have alerted the crew to their incorrect heading during the return leg.
Interesting Facts
- 01The crash was the deadliest aviation accident in Canadian history at the time of the occurrence.
- 02Five professional Canadian football players were among the victims, returning from the annual Shrine Game.
- 03The Canadair North Star was notorious for frequent false fire warning indications.
- 04The crash site on Mount Slesse remains a protected heritage site due to its extreme inaccessibility and the presence of human remains.
- 05The aircraft impacted the mountain at a speed in excess of cruising speed, likely due to the effects of severe icing and subsidence on the aircraft's flight path.
Safety Actions & Advisories
Mount Slesse Commemorative Site
Source ↗Due to the extreme difficulty of the terrain and the inability to recover all remains, the crash site was designated a protected heritage site under the Heritage Conservation Act to prevent disturbance of the wreckage and human remains.
Known Controversies & Unanswered Questions
Unexplained Navigation Error
Reference ↗Investigators could never fully explain why the experienced crew turned right into the mountains instead of left toward the safe corridor of Green Airway 1, despite having multiple functional navigation aids.