Floatplane Stall During River Departure Due to Wind Shadow and Lack of Rating

Casualties unknown • Kustatan River, AK, US

A pilot without a sea plane rating attempted a river departure in a floatplane, encountering a wind shadow from trees that caused a stall shortly after lift-off.

What happened

The pilot landed a floatplane on the Kustatan River for fishing purposes. When preparing to depart, he selected a takeoff area that required negotiating a turn while on the step of the water. He reported encountering a headwind of 10 to 12 knots initially, which shifted to a quartering headwind as he approached the lift-off point. However, trees located near the takeoff site blocked the wind, creating a virtually no-wind condition at the critical moment. The pilot did not have sufficient airspeed when the aircraft lifted off. Shortly after becoming airborne, the aircraft stalled and settled back to the surface, nosing over before coming to rest next to a sand bar. The pilot did not possess a sea plane rating.

Findings

The primary factors contributing to this accident were the pilot's lack of a sea plane rating and his failure to account for the wind shadow created by nearby trees, which resulted in an inadequate airspeed during takeoff.

Probable cause

The pilot's failure to maintain adequate airspeed during takeoff due to a wind shadow caused by trees, compounded by his lack of a sea plane rating.

Frequently asked questions

What happened in the 1985-07-31 Piper PA-18 accident near Kustatan River, AK?

A pilot without a sea plane rating attempted a river departure in a floatplane, encountering a wind shadow from trees that caused a stall shortly after lift-off.

What aircraft was involved and where did it happen?

The accident on 1985-07-31 involved a Piper PA-18, registration N1104N, at Kustatan River, AK.

What was the probable cause of the accident?

The pilot's failure to maintain adequate airspeed during takeoff due to a wind shadow caused by trees, compounded by his lack of a sea plane rating.

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20001214X36965. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.

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