N45113Air Tractor AT-502 · 1990

The pilot was attempting to takeoff for a local aerial application flight. During his flights that day, he had been monitoring a storm cell which was building to the south of the runway. He recalled that during his last landing, the windsock indicated a light wind; however, after reloading with fertilizer, he started the takeoff roll and noticed the 10-knot windsock was “completed inflated and whipping violently”. As he continued the takeoff, he felt the tail of the airplane being pushed by the wind, resulting in a back-and-forth motion. Despite being at a low speed (about 40 to 50 mph) and without pilot input, the force of the wind resulted in the airplane becoming airborne about 3 ft. The airplane then nosed down, tumbled, and came to rest inverted. He reported no mechanical malfunctions contributed to the accident, and he suspected the airplane encountered a downdraft or microburst.

A review of weather information found an area of convective weather within 10 nautical miles south-southwest of the airstrip. FAA Advisory Circular 00-24C Thunderstroms highlights that within 20 miles of a severe thunderstorm the potential exists for low-level wind shear or microburst.