CEN18FA232

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.

The 405-ft tall communications tower that the airplane collided with was constructed in 1989 and was supported by unmarked steel cables. The tower location was published on the Dallas-Fort Worth area visual flight rules sectional chart current at the time of the accident and was painted and lighted in accordance with FAA Circular 70/7460-1K, titled "Obstruction Marking and Lighting." The tower is lit 24-hrs a day and painted with FAA specification paint in alternating bands. Examination of maintenance logbooks for the airplane did not reveal any anomalies or uncorrected defects. On June 19, 2018, about 0715 central daylight time, an Air Tractor 502B, N2063B, was destroyed when it was involved in an accident near Enid, Oklahoma. The pilot was fatally injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 137 agricultural flight. According to the operator, the airplane was dispatched to apply fertilizer to a nearby field. The pilot had also applied fertilizer to that field the previous day. Preflight operations were normal and company personnel stated that the pilot was in good spirits before the flight. A 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 "twisted violently… and dropped straight down." The Board of Medicolegal Investigations, Office of the Chief Medical Examiner, Oklahoma City, Oklahoma, performed an autopsy of the pilot. The pilot's cause of death was multiple blunt force injuries. Toxicology testing was performed at the FAA Forensic Sciences Laboratory and detected 0.149 µg/ml doxylamine in the pilot's blood specimens. It was also detected in the pilot's urine. Doxylamine is a sedating antihistamine available over the counter in cold and allergy products and is also the active ingredient in some over-the-counter sleep aids. Citalopram, a prescription antidepressant, and its metabolite, desmethylcitalopram, were detected in the pilot's blood and urine. One of the witnesses, who was driving in the vicinity, reported that he saw the airplane flying in the area, and that the weather conditions were clear. The aircraft wreckage was found in an open flat wheat field north of Enid, Oklahoma. It was located about 470 ft north of a 405-ft-tall transmission tower. According to the Federal Aviation Administration (FAA) inspector who initially responded to the accident scene, the tower company identified that the top 50 ft of the tower was missing. The tower remained standing but was later taken down by the tower company on the evening of June 19, 2018. About 50 ft of dark orange tower structure and two approximately 5/8-inch diameter guy wires were intertwined with wreckage. The wreckage and ground scars were consistent with a nose-down vertical impact. There was no horizontal ground scarring or significant debris trail leading to the wreckage. Most of the wreckagewas found collocated with the fuselage. The engine was found about 325 ft northeast of the fuselage and had separated at the "C" flange. The propeller blades were found in many pieces located throughout the debris field. Some of the propeller blades exhibited evidence of a wire strike and orange paint transfer. Examination of the airplane wreckage at the accident site did not reveal any pre-impact mechanical anomalies. Flight control continuity was confirmed from the cockpit to all flight control surfaces. Thermal marks, circular scoring, and fractured turbine blades suggested that the engine was operating under some degree of power at the time of impact.