What happened
A Cessna 310I, registration C-GWWO, was performing an instrument flight rules (IFR) flight from Manning to Calgary, Alberta, when it encountered deteriorating weather conditions. During the initial descent into the Calgary area, the aircraft began accumulating light rime ice. As the aircraft proceeded on radar vectors for an ILS approach to runway 34, it entered an area of moderate icing, with ice accumulation reaching one to two inches on the wing leading edges and tip tanks.
After an unsuccessful first approach, the pilot attempted a second ILS approach. During this second maneuver, the aircraft struggled to maintain altitude and localizer alignment. At approximately 1910 mountain daylight time, the aircraft descended into a rail yard roughly 4.5 statute miles short of the runway. The aircraft struck a structure on the roof of a diesel locomotive maintenance building and came to rest in an inverted position. The pilot sustained serious injuries, while the two passengers sustained minor injuries.
The investigation
The investigation examined the aircraft's mechanical state, the pilot's performance, and the environmental conditions. Investigators found that the aircraft was not certified for flight into known icing conditions. While the engines showed no mechanical failure, evidence indicated the right engine suffered a loss of power due to fuel exhaustion. The investigation also looked into the aircraft's interior, discovering that the passenger seat rails had been installed over new carpeting and underlay rather than being secured directly to the cabin floor. This improper installation allowed the passenger seats to detach from the airframe during the impact.
Findings
Several factors contributed to the accident:
- The aircraft departed Manning with insufficient fuel to meet IFR requirements for the flight to Calgary.
- The pilot continued the flight despite being aware of forecast icing conditions, and the aircraft was not certified for such operations.
- The right engine lost power due to fuel exhaustion, a situation exacerbated by the aircraft's lateral movement and high power settings required to combat ice.
- Severe ice accumulation on the wings significantly reduced the aircraft's lifting capability, making it unable to maintain altitude.
- The weather at Calgary deteriorated more rapidly than the pilot had been led to believe by the initial forecast.
- The pilot's shoulder harness was not tightly fastened, contributing to the severity of his facial injuries.