Dehavilland DHC 2 N364RA accident near Dilllingham, Alaska

Probable cause

The pilot's failure to set the wing flaps to the "takeoff" position, which resulted in a longer-than-normal takeoff run and collision with terrain.

NTSB analysis

The pilot stated that he was departing on a postmaintenance flight check in a float-equipped airplane from a short water lane at a remote, unimproved seaplane base. While taxiing for departure, he left the wing flaps in the "up" position to aid in turning the airplane on the water. After aligning the airplane for the takeoff run, he applied full power, and the airplane accelerated onto the step. While attempting to rotate, he realized that he had forgotten to reset the wing flaps to the "takeoff" position. He attempted to reset the manually operated, hydraulically actuated wing flaps, but the incorrect flap setting led to a longer-than-normal takeoff run, and the airplane subsequently impacted the water lane's far bank, which resulted in substantial damage to the left wing and left-wing strut. The pilot reported that there were no preaccident mechanical anomalies with the airplane that would have precluded normal operation.

Text from the NTSB. Open the NTSB docket for ANC17CA038 for the full record.