On July 24, 1995, an Air Tractor AT-502 (registration N4516K) was involved in an aviation accident near Idaho Falls, ID. Investigators recorded the probable cause as: THE PILOT'S INADEQUATE AIRSPEED AT LIFTOFF. CONTRIBUTING TO THE ACCIDENT WERE HIGH DENSITY ALTITUDE, TAILWIND CONDITIONS, THE PILOT'S SELECTION OF AN EXCESSIVE TAKEOFF FLAP SETTING, AND A WINDSHEAR ENCOUNTER. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
A pilot encountered wind shear during takeoff, leading to reduced airspeed and tail contact with the runway. Despite continuing, the aircraft failed to climb and struck power poles during an attempted emergency landing.
Takeoff Encounter with Wind Shear
During the takeoff roll at 70 mph, the airplane experienced a wind shear that decreased its airspeed to below 60 mph. This event also caused the tail to drop back to the runway. The pilot elected to continue the takeoff.
Subsequent Performance Issues
After continuing the takeoff, the airplane did not achieve adequate airspeed to sustain flight before reaching the end of the airstrip. The pilot lifted off, but the aircraft began to sink immediately after becoming airborne.
Emergency Landing and Impact
In an attempted emergency landing on a road, the airplane struck a series of power poles. The accident occurred under conditions that included an 8 to 10 knot tailwind at the start of the takeoff roll and a density altitude of over 7,300 feet. Additionally, the pilot had selected a greater takeoff flap setting than was specified by the aircraft flight manual.