What happened
During the fourth flight of the day, the pilot attempted a takeoff but reported that the airplane failed to accelerate sufficiently. Because there was insufficient remaining runway to perform an aborted takeoff, the pilot continued the takeoff into a shallow climb. During this climb-out phase, the aircraft struck trees. At the time of the accident, the aircraft's hopper contained 1200 pounds of herbicide, which the pilot did not dump during an emergency procedure.
The investigation
An examination of the engine was conducted to determine if a mechanical failure contributed to the lack of acceleration. The investigation revealed no mechanical malfunction that would have caused a partial loss of power. Further inquiry into the pilot's credentials found that the pilot did not possess an Agricultural Operator Certificate as required by 14 CFR 137.11. Additionally, investigators found no documentation proving the pilot had received necessary training in aerial operations per 14 CFR 137.19(e).