On July 31, 1987, a Lake LA-4-250 (registration N14037) was involved in an aviation accident near Westport, NY. Investigators recorded the probable cause as: Premature lift-off during takeoff on rough water, leading to a nose-first impact with a large wave that caused the aircraft to invert. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
An amphibian aircraft lifted off prematurely during takeoff on a lake, struck a large wave nose-first, and inverted. Occupants escaped through a window before the cabin submerged.
What happened
During the takeoff run on a lake, the amphibious aircraft entered rough water conditions and became airborne prematurely. The aircraft settled onto the water surface in a slightly nose-high attitude, touching down directly in front of a large wave. The nose impacted the wave head-on, which nearly brought the plane to a complete stop. Within seconds, the nose sank, causing the aircraft to become inverted. The occupants exited through a window that had come loose during the impact. The aircraft continued to float, although the cabin area was completely submerged.
Findings
The primary factors contributing to this accident were the premature lift-off during takeoff and the subsequent nose-first impact with a large wave on the water surface. These events led to the inversion of the amphibious aircraft and the submersion of the cabin.
Probable cause
Premature lift-off during takeoff on rough water, leading to a nose-first impact with a large wave that caused the aircraft to invert.