Grumman G-44 N139F accident near Aleknagik, Alaska

Probable cause

The pilot's decision to make multiple low passes over the glassy surface water, which resulted in an impact with the surface of the lake.

NTSB analysis

The pilot of the twin-engine seaplane was en route to a remote lake to pick up passengers. A passenger who was awaiting pickup witnessed the accident and said that when the airplane arrived in the area, it made multiple passes over the lake and island where he was waiting. After the third pass, the airplane came into view very low over the water. The airplane banked to the left, and the left wing float struck the water. The airplane veered sharply to the left, bounced, and cartwheeled three times. The airplane came to rest, partially submerged, with its high-mounted wings level with the surface of the water. The witness was unable to reach the airplane due to the icy water, and the airplane subsequently sank in the lake and was not recovered. The witness did not see the pilot.

The witness reported that the weather conditions at the time of the accident consisted of calm wind, low clouds, light rain, and fog restricting the visibility. He further described the water as glassy. It is likely that, due to visibility and water conditions, the pilot misjudged the height above the surface of the lake during a low pass, resulting in the left wing float inadvertently contacting the surface of the lake.

Text from the NTSB. Open the NTSB docket for ANC13FA001 for the full record.