Accident Overview
A certificated airline transport pilot was conducting a personal flight under 14 CFR Part 91 to deliver a load of wooden roofing shakes to a friend's remote lodge. Shortly after takeoff, the aircraft experienced a series of unusual movements and ultimately impacted shallow water in a tidal mudflat area.
Witness Observations
Witnesses reported that after the aircraft reached an altitude of about 200 to 300 feet, it abruptly pitched up approximately 70 degrees and began drifting to the right. The aircraft continued turning right while the nose momentarily lowered. As the aircraft flew very slowly, the landing gear was extended. The nose then pitched up again, the right wing dropped, and the aircraft descended. One witness described the descent as the wings rocking back and forth, similar to a card in the wind, with the nose slightly higher than the wings.
Investigation Findings
A postaccident investigation determined that the estimated gross weight at takeoff was 11,500.8 pounds, which exceeded the maximum takeoff gross weight by 1,400.8 pounds. The exact center of gravity could not be calculated because the precise location of the cargo was unknown. Examination of the aircraft found no evidence of any preexisting mechanical anomalies.
Probable Cause
The official probable cause was the pilot's excessive loading of the airplane that precipitated an inadvertent stall/mush during the initial climb.