History of Flight
On August 8, 2019, about 0721 central daylight time, an Air Tractor AT-502B, registration N6113C, was destroyed when it struck power lines and crashed near Sumner, Iowa. The pilot was fatally injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 positioning flight.
The flight originated from Mt. Pleasant Municipal Airport, Mt. Pleasant, Iowa, about 0615, destined for Oelwein Municipal Airport (OLZ), Oelwein, Iowa. A witness at OLZ reported that the pilot overflew the runway but continued north. The airplane appeared intact, and the engine seemed to run normally.
According to multiple witnesses, the airplane continued about 14 miles north of OLZ before turning south. Witnesses about 2-1/2 miles north of the accident site observed the airplane at low altitude in level flight with normal engine operation.
A witness near the accident site saw the airplane approach from the west-northwest in a constant 20° left turn. The airplane struck power lines without apparent flightpath change, then nearly struck a building before hitting a second set of power lines. It veered left, the nose dropped, and it impacted a road, skidded across, and came to rest against a large tree. A postimpact fire ensued. The witness described the airplane at very low altitude, intact, with normal engine sound, maintaining the shallow left turn without climbing or descending.
Personnel Information
The pilot's logbook was unavailable during the investigation. On his most recent medical certificate application, he reported no medications and diet-controlled diabetes. He was involved in a wire strike in the accident airplane 8 days before the accident. Witnesses noted that after that strike, the pilot seemed shaken, and he was heard coughing and vomiting several days later.
Aircraft and Maintenance
The owner of an agriculture operation based at OLZ noted damage to the propeller, windshield, and spray boom after the previous wire strike. The airplane remained at OLZ until repairs were completed; the engine and propeller were removed, and the airplane was returned to service 3 days before the accident. A maintenance entry dated August 5, 2019, indicated that the engine power section was removed for unscheduled inspection due to a propeller strike, repaired, reinstalled, and approved for return to service.
Meteorological Information
Sunrise occurred at 0608. At the accident time, the sun was about 12° above the horizon at azimuth 079° relative to true north.
Wreckage and Impact Information
Damage to two sets of power lines, a small roof-mounted antenna on a single-story building, and a power line support pole was consistent with the airplane striking them before impacting a two-lane road and coming to rest against a large tree. The accident site was in the yard of a mixed-use commercial/residential building. The main wreckage comprised the fuselage, right wing, inboard portion of the left wing, and empennage. The outboard left wing and left aileron had separated and were near the power line support pole. The engine with propeller attached had separated from the airframe. A postimpact fire consumed most of the fuselage.
Postaccident airframe examination found no evidence of in-flight structural failure or flight control anomaly. Engine examination revealed circumferential contact marks consistent with rotation at impact, with no preimpact failure or malfunction observed.
Medical and Pathological Information
An autopsy conducted by the Iowa Office of the State Medical Examiner attributed the pilot's death to multiple blunt force injuries with thermal injuries. The autopsy identified evidence of heart disease, a subarachnoid hemorrhage that appeared several days old, pulmonary hypertension, and chronic kidney disease. Medical records indicated the pilot received dialysis for kidney disease and was being treated for diabetes, described by his primary care doctor as "not well controlled." He had a history of coronary artery disease treated with stent placement and high blood pressure treated with medication.
Toxicology testing performed by the Federal Aviation Administration Forensic Sciences Laboratory detected hydrocodone and dihydrocodeine, fentanyl and norfentanyl, trazodone, and yohimbine in heart blood and liver tissue. Hydrocodone and fentanyl were prescribed for chronic pain due to spinal stenosis; both are opioid analgesics with potential for impairment. Dihydrocodeine and norfentanyl are metabolites of hydrocodone and fentanyl, respectively. Trazodone was prescribed for anxiety; it is a serotonin modulator that may impair mental and/or physical ability for hazardous tasks. Yohimbine, used as a dietary supplement, has stimulant effects and may impair mental and physical ability for hazardous tasks.