Accident Details
On the day of the accident, a Douglas DC-3 departed Points North Landing, Saskatchewan, at approximately 1125 central standard time on a visual flight rules cargo flight to Ennadai Lake, Nunavut. The aircraft was carrying two pilots and 6600 pounds of cargo, which included building materials for the construction of a lodge. The flight was one of a series of such trips; the pilots had completed a similar flight earlier that day.
The runway at Ennadai Lake was an ice strip oriented northeast/southwest, measuring approximately 2700 feet long and 150 feet wide, marked with small evergreens. The ice strip was constructed on the lake with flat, obstacle-free approaches. Snow had been cleared so that no snow ridges existed at the runway ends.
The arrival toward the southwest appeared similar to previous landings. Witnesses observed the aircraft touch down nearly halfway along the ice strip, with the tail remaining airborne, and the aircraft took off almost immediately. The main landing gear was seen to retract. The aircraft reached the end of the runway, then abruptly entered a steep, nose-up attitude, banked sharply left, turned left, and descended into the ice. The left wing made first contact, after which the aircraft rotated around the left wing and struck the ice in a steep, nose-down attitude approximately 400 feet from the end of the strip. There was no post-impact fire. Both crew members were killed instantly. Canadian Forces rescue specialists were air-dropped to the site on the day of the accident.
Investigation Findings
The investigation identified several findings as to causes and contributing factors. The pilot lost control of the aircraft while conducting a go-around from a balked landing on the ice strip. The aircraft's center of gravity on the accident flight was beyond its aft limit. The actual center of gravity at basic operating weight was 16.7 inches aft of the value provided in the weight and balance report. The load sheet index number used by the crew was inaccurate. Additionally, a stack of 2x4 lumber was inadequately secured and may have shifted rearward during the go-around. The crew did not recalculate the aircraft's weight and balance for the second flight. Leaks in the heater shroud allowed carbon monoxide gas to contaminate both the cockpit and cabin air. The captain's carboxyhaemoglobin level was 17.9%, which may have adversely affected his performance, particularly decision making and visual acuity.
Other findings included that the carbon monoxide detector had no active warning system and its user directions were obscured when installed. The company maintenance facility overhauled the heater as required by the Transport Canada-approved inspection program. However, the manufacturer's maintenance instruction manual for the S200 heater did not specify intervals for inspection and overhaul. No maintenance instructions were available for that specific heater part number, and the facility did not conduct inspections, overhauls, or pressure decay tests as specified for later manufactured heaters.