Event Description
During a low-level agricultural spray run, the pilot aligned the aircraft adjacent to the previous day's run and activated the spray system to disperse herbicide. Analysis of Satloc flight data for that run showed no spray flow recorded—the only such occurrence in 10 days of data, including previous runs over the same fields. The spray run lasted approximately 40 seconds.
Warning and Pilot Attention
It is likely that a visual warning indicating no flow was displayed on the Satloc system immediately after spray activation. The pilot would have had sufficient opportunity to notice the message during the run. Additional cockpit and external sources also indicated no flow, providing crosschecking capability. The Satloc screen and other sources were within the pilot's field of view. While the pilot's primary focus would be outside the aircraft, the Satloc screen was part of the visual scan during spray runs. As the warning was visual only, it relied on the pilot scanning the display to be noticed.
When attention diverts from outside to inside the cockpit, external monitoring can be reduced, and inadvertent deviations may go unnoticed. At 120 knots and approximately 10 feet altitude, the aircraft travels about 60 meters per second, and even small attitude changes could be imperceptible but lead to terrain collision.
Analysis and Conclusion
The investigation considered potential reasons for the no flow warning, including high temperatures and lack of vegetation in the field, but could not confirm if spray was dispersed. Damage to the aircraft made it difficult to determine if dispersal system damage occurred before or after the collision. With no other reasonable explanation, and after excluding aircraft malfunction, pre-existing medical conditions, and environmental factors, it was likely that focusing on the no flow message, even momentarily, diverted the pilot's attention away from outside the aircraft. Consequently, the aircraft inadvertently descended. Given the low altitude during the spray run, there was insufficient height to recover, and the aircraft touched the ground, subsequently colliding with an irrigation levee.