Air Tractor Inc AT 502B N2063B accident near Enid, Oklahoma

Probable cause

The pilot's failure to see and avoid a known obstacle (communications tower) during agricultural spraying operations.

NTSB analysis

The agricultural airplane was dispatched to apply fertilizer to a nearby field that he had fertilized the previous day. One witness observed the airplane make 8-10 passes over the field then saw the airplane fly low, pop up, and make a turn. According to the witness, the airplane ran into the guy wire of a tower and then the airplane "twisted violently…and dropped straight down." The 405-ft-tall tower was properly painted and lighted and was marked on the sectional chart. Examination of the accident site revealed that the airplane struck the top portion of the tower and impacted the ground in a near-vertical attitude.

Detailed examination of the airplane and engine did not reveal any pre-impact mechanical anomalies that would preclude normal operation. Toxicology testing detected doxylamine, a potentially impairing sedating antihistamine, in the pilot's blood and urine. While the detected level was within the normally sedating range, because doxylamine undergoes postmortem redistribution, levels in postmortem blood may be elevated above antemortem levels. Therefore, whether the pilot was impaired by the sedating effects of doxylamine at the time of the accident could not be determined. Additionally, the toxicology testing identified an antidepressant, citalopram, in the tested samples. Citalopram itself is not known to cause significant impairment but major depression can significantly affect judgment, response time, and executive functioning. However, because the pilot's health care prescriber could not be identified, the extent of any potential depressive symptoms at the time of the accident could not be determined.

Text from the NTSB. Open the NTSB docket for CEN18FA232 for the full record.