Air Tractor Inc AT 502B N502WC and Air Tractor Inc AT 502B N5044N accident near Zamora, California

Probable cause

The failure of both pilots to maintain an adequate visual lookout, which resulted in a midair collision. Also causal was the pilot's use of two sedating antihistamines and two impairing medication and the effect of sun glare on his visual lookout, which likely led to his inability to successfully see and avoid the other airplane.

The failure of both pilots to maintain an adequate visual lookout, which resulted in a midair collision. Also causal was the other pilot's use of two sedating antihistamines and two impairing medication and the effect of sun glare on his visual lookout, which likely led to his inability to successfully see and avoid the other airplane.

NTSB analysis

Both agricultural application airplanes were returning to their respective home bases after completing application operations when they collided in-flight at an altitude less than 500 ft agl. Following the collision, one of the airplanes (N502WC) descended to ground contact, fatally injuring the pilot. The pilot of the second airplane (N5044N) performed a forced landing to a field. That pilot reported that he did not see the other airplane until immediately before the collision.

Examination of the engine and flight control systems of both airplanes revealed no mechanical anomalies that would have precluded normal operation including the ability to maneuver the airplanes away from each other.

The deceased pilot had at least therapeutic levels of two impairing medications, cyclobenzaprine and hydrocodone, at the time of the accident. In addition, he had low levels of two sedating antihistamines, chlorpheniramine and diphenhydramine. These four drugs, in combination, would likely have slowed his psychomotor functioning and decreased his attentiveness to the flight environment. Therefore, it is likely that the fatally injured pilot's use of a combination cyclobenzaprine, hydrocodone, and two sedating antihistamines, contributed to his inability to successfully see and avoid the other airplane.

Based upon the sun's position and the statement from the second pilot, the sun was likely in the eyes of the deceased pilot. There was no evidence of the deceased pilot performing any evasive maneuver prior to the collision, which suggests that he never visually acquired the other airplane prior to the collision.

Both agricultural application airplanes were returning to their respective home bases after completing application operations when they collided in-flight at an altitude less than 500 ft agl. Following the collision, one of the airplanes (N502WC) descended to ground contact, fatally injuring the pilot. The pilot of the second airplane (N5044N) performed a forced landing to a field. That pilot reported that he did not see the other airplane until immediately before the collision.

Examination of the engine and flight control systems of both airplanes revealed no mechanical anomalies that would have precluded normal operation including the ability to maneuver the airplanes away from each other.

The deceased pilot had at least therapeutic levels of two impairing medications, cyclobenzaprine and hydrocodone, at the time of the accident. In addition, he had low-levels of two sedating antihistamines, chlorpheniramine and diphenhydramine. These four drugs, in combination, would likely have slowed his psychomotor functioning and decreased his attentiveness to the flight environment. Therefore, it is likely that the fatally injured pilot's use of a combination cyclobenzaprine, hydrocodone, and two sedating antihistamines, contributed to his inability to successfully see and avoid the other airplane.

Based upon the sun's position and the statement from the second pilot, the sun was likely in the eyes of the deceased pilot. There was no evidence of the deceased pilot performing any evasive maneuver prior to the collision, which suggests that he never visually acquired the other airplane prior to the collision.

Text from the NTSB. Open the NTSB docket for WPR16FA148 for the full record.