Accident Details
On a day visual flight rules flight, a float-equipped Transwest Air Limited Partnership DHC-3 turbine Otter, registration C-FSGD, departed Scott Lake, Northwest Territories, at approximately 1850 Central Standard Time. The intended destination was Ivanhoe Lake, Northwest Territories, a distance of 33 nautical miles. The aircraft did not arrive at its destination and was reported overdue at approximately 2100. The Joint Rescue Coordination Centre Trenton was notified by the company. No emergency locator transmitter signal was received. A search and rescue C-130 Hercules aircraft was dispatched. The aircraft wreckage was located on 23 August 2013, in an unnamed lake, 10 nautical miles north of the last reported position. The pilot, who was the sole occupant of the aircraft, sustained fatal injuries.
Investigation Findings
The investigation determined that during approach to landing on the previous flight, the right-wing leading-edge and wing tip were damaged by impact with several trees. This damage was not evaluated or inspected by qualified personnel prior to the departure on the accident flight. The investigation also found that cumulative unmanaged stressors disrupted the pilot’s processing of safety-critical information and likely contributed to an unsafe decision to depart with a damaged, uninspected aircraft. The aircraft was operated in a damaged condition and departed controlled flight, likely due to interference between parts of the failing wing tip, acting under air loads, and the right aileron.
Other findings included that the emergency locator transmitter did not activate due to crash damage and submersion in water. Additionally, the aircraft was not fitted with FM radio equipment typically carried by aircraft servicing the lodge; lodge personnel did not have a means to contact the pilot once the aircraft moved away from the dock.
Probable Cause
The probable causes, as stated in the official findings, are: 1. During approach to landing on the previous flight, the right-wing leading-edge and wing tip were damaged by impact with several trees. 2. The damage to the aircraft was not evaluated or inspected by qualified personnel prior to take-off. 3. Cumulative unmanaged stressors disrupted the pilot’s processing of safety-critical information, and likely contributed to an unsafe decision to depart with a damaged, uninspected aircraft. 4. The aircraft was operated in a damaged condition and departed controlled flight likely due to interference between parts of the failing wing tip, acting under air loads, and the right aileron.