Air Tractor AT 502 N7314D accident near Harlingen, Texas

Probable cause

The pilot’s failure to maintain clearance from power transmission lines during low altitude flight operations. Contributing to the accident was the pilot’s impairment due to a sedating medication.

NTSB analysis

The pilot was conducting an agricultural flight when witnesses observed the airplane flying at a low altitude before it collided with power transmission lines and terrain. The airplane was destroyed during a postimpact fire. Examination of the airplane wreckage did not reveal any preimpact mechanical malfunctions or failures that would have precluded normal operation.

Toxicology testing detected the sedating antihistamine diphenhydramine in the pilot’s blood. Considering that postmortem redistribution of diphenhydramine may result in central levels being two-to-three times higher than peripheral levels, the circulating level was likely in the therapeutic range at the time of the accident. Given the pilot’s years of experience and familiarity with the agricultural airplane, it is reasonable to consider diminished reaction times and flying performance attributable to the use of sedating medication likely contributed to the accident.

Text from the NTSB. Open the NTSB docket for CEN19FA117 for the full record.