Aviat Aircraft Inc A-1B N55HU accident near North Bend, Washington

Probable cause

The pilot's failure to predetermine the depth of the snow on the runway.

NTSB analysis

The pilot reported that during a local area personal proficiency flight, he decided to make a full-stop landing on the snow-covered runway of a remote state airstrip. Although he overflew the strip before landing, because he had not predetermined the actual depth of the snow on the surface, during the landing roll the airplane sunk deep enough into the snow that it decelerated at a rate that resulted in it nosing over onto its back. The pilot did not report any airplane malfunctions or anomalies, and he further stated that the accident could have been prevented if he had not landed without first acquiring an "exact verification" of the snow depth on the runway surface.

Text from the NTSB. Open the NTSB docket for WPR11CA065 for the full record.