What happened
The pilot elected to conduct a takeoff from a body of water that measured approximately one-half mile in length. The lake was oriented on an east-west heading, which necessitated a crosswind departure given the prevailing wind conditions. During the initial phase of the run, the pilot encountered difficulty getting the aircraft to rotate and lift off the surface.
Despite the struggle to achieve flight, the pilot decided to continue the takeoff roll rather than aborting. The aircraft eventually became airborne but failed to accelerate sufficiently while remaining in ground effect. Consequently, the aircraft impacted a nearby tundra hill while still operating at low altitude within the ground effect envelope.
The investigation
Post-accident interviews with the pilot revealed significant contributing factors related to human performance. The pilot stated that he was experiencing fatigue at the time of the operation. He also admitted to being overconfident in both his own abilities and the capabilities of the aircraft.
The pilot acknowledged that better decision-making could have prevented the accident. Specifically, he noted that he should have waited for wind conditions to align with the axis of the lake or repositioned the aircraft on a larger body of water before hauling the heavy cargo load.