On August 16, 1991, an Air Tractor AT-502 (registration N4535K) operated by Gregory L. Kubin was involved in an aviation accident near Clovis, NM. Investigators recorded the probable cause as: The pilot's failure to see and avoid terrain during the final swath run at dusk, which resulted in a collision with a dirt berm. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
An agricultural aircraft struck a dirt berm at the end of a field during its final swath run at dusk, causing an engine fire that destroyed the plane. The pilot successfully dumped his load and landed safely.
What happened
The pilot was conducting agricultural operations during the final swath run of the day as daylight faded. While approaching the end of the field, the pilot failed to perceive a rise in the terrain ahead. Consequently, the aircraft impacted a dirt berm located at the terminus of the spray area.
Upon impact, the aircraft engine immediately caught fire. In response to the emergency, the pilot dumped the remaining load of fertilizer and fungicides from the aircraft. Following the dump, the pilot managed to land the aircraft. The subsequent fire caused by the impact destroyed the aircraft completely.
Probable cause
The pilot's failure to see and avoid terrain during the final swath run at dusk, which resulted in a collision with a dirt berm.