Background
At approximately 0900 eastern standard time on the day of the accident, the pilot arrived at the airstrip and prepared the ski-equipped de Havilland DHC-3 (Otter) aircraft, registration C-GOFF, serial number 65, which was equipped with a turbine engine. Two passengers, along with supplies for an extended period including a snowmobile and camping gear, were to be flown to a remote location. The pilot loaded the aircraft and waited for the weather to improve.
Accident Sequence
At approximately 1200 EST, the pilot and passengers boarded and took off in an easterly direction. The aircraft became airborne near the departure end of the airstrip. Shortly after takeoff, the right wing struck several small bushes and the top of a birch tree. The aircraft then descended and struck the frozen lake surface, about 70 feet below the airfield elevation, in a steep, nose-down, right-wing-low attitude. When it came to rest, the aircraft was inverted and partially submerged, with only the aft fuselage above the ice. All occupants were wearing lap belts. The pilot and front seat passenger sustained fatal injuries. The rear seat passenger survived the impact and evacuated with difficulty due to leg injuries. Approximately 22 hours after the accident, a local air operator searching for the missing aircraft located and rescued the surviving passenger.
Investigation
The investigation determined that the pilot had originally intended to taxi along the airstrip to pack down the snow but did not do so. The snow depth was approximately 18 inches, and the skis plowed through the snow, impeding acceleration. The aircraft accelerated slowly, and near the end of the airstrip, the pilot forced the aircraft into the air with insufficient airspeed to climb out of ground effect and clear obstacles. The aircraft was at or near stall when it struck the brush and tree, then departed controlled flight and crashed. The pilot did not attempt to abort the takeoff.
The aircraft's ELT did not activate, likely because it was equipped with a unidirectional G switch. Even if it had activated, the external ELT antenna was severed during impact, which would have prevented alerting rescue coordination.
The investigation also found that the aircraft's certificate of airworthiness was affected as it had flown more flights than allowed by a ferry permit. Additionally, the rear passenger seat was installed incorrectly, contrary to de Havilland Alert Service Bulletin A3/49.
Findings
The Transportation Safety Board of Canada determined the causes and contributing factors: The pilot attempted takeoff from an airstrip covered with approximately 18 inches of snow, and the aircraft did not accelerate to takeoff speed due to drag; the aircraft was forced into the air and could not climb out of ground effect. The pilot did not abort the takeoff when it became apparent the aircraft was not accelerating normally. A risk identified was that unidirectional G switches in many ELTs may not activate if impact forces are not aligned with the usual direction of flight.
The accident report was released on 16 October 2004.