On October 18, 1996, an Air Tractor AT-502 (registration N4549Z) was involved in an aviation accident near Throckmorton, TX. Investigators recorded the probable cause as: failure of the pilot to maintain clearance of a transmission wire during pullup from a swath run. The proximity of the transmission wire was a related factor. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
An aerial application aircraft caught an unmarked electrical wire during a swath run pull-up, causing an uncontrolled turn and ground impact; the aircraft was destroyed by postimpact fire.
Accident Overview
The pilot of an aerial application aircraft reported conducting a swath run in a north-to-south direction. During the pull-up maneuver, the main landing gear, which lacked wire cutters, snagged an east-to-west oriented unmarked electrical transmission wire.
Sequence of Events
The pilot stated that the east end of the wire became entangled in the aircraft's rudder horn, forcing the airplane into an uncontrolled left turn. The combined engine power and momentum of the aircraft were sufficient to snap three telephone poles. Subsequently, the airplane impacted terrain and came to rest inverted. A postimpact fire destroyed the aircraft.
Investigation Details
The investigation focused on the unmarked electrical transmission wire and the absence of wire cutters on the landing gear. The pilot's report provided key details on the entanglement and the resulting loss of control.