What happened
During the predawn hours of an Arctic morning, a scheduled commuter flight was preparing for a journey to a nearby village. The flight was carrying cargo and seven passengers. At the time of the accident, heavy frost was present on airport vehicles and aircraft. A ground technician noted a thin layer of ice covering the upper surface of the left wing of the aircraft type.
In an effort to depart on schedule, the pilot proceeded with the flight without performing deicing procedures. During the fueling process, the pilot instructed the technician to load fuel into the left wing only. This created a significant weight discrepancy, leaving the left wing heavier by an amount between 450 and 991 pounds. Following takeoff, the pilot executed the first turn toward the heavier side. The aircraft was seen climbing past the runway threshold before descending vertically into the water. There were no mechanical failures identified in the engine or the airframe prior to the impact.
Findings
Investigations revealed that the aileron trim indicator was set to a full right wing down position. Subsequent flight testing demonstrated that the fuel imbalance required approximately half of the available right wing down aileron deflection just to maintain level flight. This left only half of the necessary control authority for maneuvering. The presence of frost on the wings is a critical factor, as it can increase stall speeds by 20% to 40% and cause asymmetric stalls. In this instance, the combination of asymmetric fuel weight and ice accumulation likely compromised the aircraft's ability to maintain controlled flight during the turn.