The sport pilot reported that he was landing his float-equipped, experimental amateur-built Zenith CH-701 on a smooth and glassy lake near Palmer, Alaska.

During the approach, just before touchdown, the airplane encountered a slight downdraft, and the airplane’s right float struck the water, which pivoted it to the right.

The left wing subsequently struck the water, and the airplane nosed over and sank.

The pilot reported no mechanical anomalies that would have precluded normal operations.

Probable cause: The pilot’s excessive descent rate and subsequent hard landing during the landing flare/touchdown.

NTSB Identification: ANC15CA024

This May 2015 accident report is provided by the National Transportation Safety Board. Published as an educational tool, it is intended to help pilots learn from the misfortunes of others.