On September 14, 2002, an Air Tractor AT-301 (registration N23736) was involved in an aviation accident near Altus, OK. Investigators recorded the probable cause as: The pilot's failure to maintain adequate clearance from electrical wires while maneuvering the airplane during agricultural operations, which resulted in the separation of the vertical stabilizer and rudder. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
An agricultural pilot attempting to navigate between electrical wires while spraying crops struck a vertical stabilizer, causing it to detach before a forced landing.
What happened
An agricultural pilot was conducting crop dusting operations, specifically spraying malathion onto a field. During the operation, the pilot attempted to maneuver the aircraft through a gap between electrical wires. While executing this low-level flight path, the vertical stabilizer of the airplane made contact with one of the overhead power lines.
The impact caused a section of the vertical stabilizer and the rudder to separate from the main airframe. Following the structural failure, the pilot initiated an emergency forced landing in an adjacent wheat field. During the touchdown sequence, the aircraft began to cartwheel across the ground surface. The airplane eventually came to a stop in an inverted position.
The investigation
The physical evidence indicated that the primary damage was concentrated on the empennage of the aircraft. The separation of the vertical stabilizer and rudder was directly attributed to the collision with the electrical infrastructure during the agricultural application phase.
Probable cause
The pilot's failure to maintain adequate clearance from electrical wires while maneuvering the airplane during agricultural operations, which resulted in the separation of the vertical stabilizer and rudder.