Amateur-built 3000 N57TJ accident near Bellevue, Washington

Probable cause

The pilot’s loss of airplane control after encountering a lake swell and skipping during takeoff.

NTSB analysis

The pilot was conducting a personal flight in the amphibious airplane with one passenger. During the step phase of the water takeoff (when most of the seaplane’s weight is supported by lift rather than the buoyancy of the floats), the airplane impacted a lake swell, leading it to skip, then pitch up and bank to one side before impacting the water.

Postaccident examination revealed no anomalies with the airframe or engine that would have precluded normal operation, and witness accounts indicated that the engine was producing power at the time of the accident. The left forward shoulder harness inertia reel and webbing were not found during the examination and were likely not installed because photographs of previous flights showed no shoulder harness at the pilot’s seat position. This likely contributed to the severity of the pilot’s injuries.

A video recording of the accident sequence was consistent with witness observations and showed calm water near the shoreline and a slow-moving lake swell in the area where the skipping occurred.

Glassy water can give the impression of calm and safety, but it can also be dangerous due to a lack of visual cues and the potential for sudden changes in water conditions. It is likely that the lake swell was not aligned with the pilot’s intended direction of departure, which resulted in the skipping and loss of control during takeoff.

Text from the NTSB. Open the NTSB docket for WPR23FA344 for the full record.