On July 12, 1995, an Air Tractor AT-301 (registration N8673S) was involved in an aviation accident near Grygla, MN. Investigators recorded the probable cause as: THE PILOT'S FAILURE TO MAINTAIN ALTITUDE AND/OR CLEARANCE AT THE BEGINNING OF THE SPRAY RUN. A FACTOR WAS TURBULENCE DUE TO THE DIFFERENT AIR TEMPERATURES OF ADJOINING TERRAIN. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
While flaring for a spray run over a wet sunflower field bordered by tall trees, the airplane descended into the crop and struck the ground. No mechanical anomalies were found.
Accident Overview
The pilot had completed three spray runs over a sunflower field and was flaring in preparation for the fourth when the airplane descended into the sunflowers and collided with the ground. An on-scene investigation found no mechanical issues with the airframe or engine that would have prevented normal flight.
Environmental Conditions
Discussions with the pilot revealed that the sunflower field was wet. The surrounding area consisted of pastures and a hayfield that had recently been cut. The outside air temperature was 90 °F. The approach to the field was bordered by a line of trees 30 ft high.
Investigation Findings
The investigation did not identify any pre-existing mechanical anomalies. The combination of the wet field, high temperature, and adjacent tree line may have been relevant, but no explicit causal factors were stated in the source material.