NTSB Factual Report

On September 14, 2000, at 1810 central daylight time, an Air Tractor AT-502 agricultural airplane, N1508V, was substantially damaged when it impacted an antenna tower and terrain while maneuvering near Lariat, Texas. The commercial pilot, sole occupant, was fatally injured. The airplane was registered to and operated by Locker Flying Service of Muleshoe, Texas. Visual meteorological conditions prevailed and a flight plan was not filed for the 14 Code of Federal Regulations Part 137 aerial application flight. The flight originated from Muleshoe, Texas, at an unknown time.

According to the FAA inspector, who responded to the accident site, a witness observed the airplane making several spray passes over the field in which the antenna tower was located. The witness observed the aircraft making a "very low spray pass." He then observed the airplane pull nose up and bank to the left. The right wing "caught the uppermost guy wire on the north side of the antenna." Subsequently, the wire snapped "causing the upper part of the tower to fall." The witnessed added that the impact with the wire had "disrupted the flight of the aircraft by spinning it to the right." The airplane then impacted the ground and caught fire.

According to FAA records, the pilot had accumulated approximately 15,750 total flight hours, of which an unknown amount were in the accident airplane. An autopsy on the pilot was performed at the Lubbock County Medical Examiner's Office, Lubbock, Texas. According to the Medical Examiner, the pilot died as a result of "blunt impact to [the] torso and extremities and 26% total body surface burns." Toxicology tests for drugs and alcohol were performed on the pilot. According to the toxicology results, 0.071 ug/ml of diphenhydramine was detected in the pilot's blood, and an unquantified amount was found in the urine. Also present in the pilot's blood was 2.035 ug/ml of acetaminophen. Diphenhydramine is an over-the-counter antihistamine used in symptomatic management of allergic symptoms and also for its sedative, antitussive and antispasmodic effects (commonly known by the trade name Benadryl). Acetaminophen is an over-the-counter drug for pain relief (commonly known by the trade name Tylenol).

The American College of Physicians-American Society of Internal Medicine conducted a study (Effects of Fexofenadine, Diphenhydramine, and Alcohol on Driving Performance) on the effects of diphenhydramine on driving performance. The results of that study indicated that "Participants had significantly better coherence after taking alcohol or fexofenadine (Allegra) than after taking diphenhydramine...After participants took diphenhydramine, driving performance was poorest, indicating that diphenhydramine had a greater impact on driving than alcohol did."

NTSB Probable Cause

The pilot's failure to maintain clearance with the antenna guy wire. A factor was the pilot's physical impairment from his use of diphenhydramine.