What happened
The pilot was conducting aerial application operations on a sunflower field adjacent to an irrigated alfalfa field. During the third pass of the spraying operation, the pilot pulled up from the swath run and initiated a procedure turn-around over the nearby alfalfa field. As the aircraft entered the turn, it rolled into an inverted attitude before pitching downward and impacting the ground.
The investigation
Investigators examined the wreckage and determined there were no pre-impact mechanical failures or system malfunctions that would have prevented continued flight. The accident site was located at an elevation of 1860 feet above mean sea level. Environmental conditions at the time included a temperature of approximately 85 degrees Fahrenheit and an altimeter setting of 30.12 inches of mercury.
Findings
A critical factor in the accident was the location of the turn relative to the irrigation system. The turn was executed downwind from the active irrigation sprinklers, which significantly altered the local atmospheric conditions. Humidity levels in the vicinity of the turn were estimated to be approximately 80 percent, a stark contrast to the roughly 40 percent humidity observed over the sunflower field where the prior runs had taken place. This localized increase in moisture likely contributed to reduced aircraft performance or control effectiveness during the low-altitude maneuver.
Safety message
Pilots conducting agricultural operations should be aware of how nearby irrigation systems can create localized pockets of high humidity and potential air density changes. These conditions may affect aircraft performance, particularly during slow-speed maneuvers such as turns at low altitude.