Cessna 421 N84HA accident near St. Marys, Pennsylvania

Probable cause

The pilot’s decision to continue the approach to a snow-covered runway in low-visibility conditions with limited ability to visually differentiate the left runway edge from the snow berm that ran along that side of the runway.

NTSB analysis

After the pilot performed a GPS approach in light snow and with 0.5-mile visibility, the airplane touched down on the left edge of the snow-covered runway and struck a snow berm. The airplane slid along the snow berm before it rotated about 210° and came to a stop. The airplane sustained substantial damage to the forward fuselage, the pressure bulkhead, and the floor area forward of the bulkhead.

The runway, its markings, and the runway lighting were covered in snow that was 3 to 4 inches deep. The snow depth, combined with the limited visibility, likely resulted in the pilot’s difficulty in identifying the runway edge from the snow berm on the left side of the runway. The notices to air mission (NOTAM) published for the airport did not contain any field conditions noting the snow depth or the snow-covered runway lights. Furthermore, the airport manager, who was new to the position, was not able to issue a NOTAM about the runway conditions because he had not yet been authorized to do so.

Text from the NTSB. Open the NTSB docket for ERA21LA134 for the full record.