Cash, AR, USA
N4257R
AIR TRACTOR INC AT 602
The commercial pilot was conducting his sixth agricultural load application of the day. Witnesses observed the airplane make a low-altitude turn and subsequently enter a spin with a nose-low attitude . The airplane subsequently impacted a rice field adjacent to the field being treated. Postaccident examination of the airframe, engine, and propeller revealed no evidence of any preimpact mechanical malfunctions or anomalies that would have precluded normal operation. The pilot's autopsy revealed that he had severe coronary artery disease with evidence of associated heart muscle injury. No evidence was found indicating that the pilot was aware of his health issues. The coronary artery disease increased the pilot's risk of a cardiac event, which would have resulted in shortness of breath, dizziness, lightheadedness, or an irregular heart rhythm (arrhythmia) with decreased cardiac output and loss of consciousness. The combination of the normal stress associated with low-altitude maneuvering and decreased cardiac output likely resulted in a sudden decrease of blood flow to the brain and the pilot's incapacitation, which resulted in his loss of airplane control.
HISTORY OF FLIGHT On July 8, 2017, about 1453 central daylight time, an Air Tractor, Inc., AT-602 airplane, N4257R, impacted terrain near Cash, Arkansas. The pilot was fatally injured, and the airplane was destroyed. The airplane was registered to and operated by Quad Rabbit, Inc., as a Title 14 Code of Federal Regulations Part 137 agricultural application flight. Day visual meteorological conditions prevailed for the local flight, which departed from a private airstrip about 1449. According to operator personnel, the pilot was conducting his sixth load application of the day and was spreading fertilizer. Two witnesses located near the accident site reported seeing the airplane make a low-altitude turn and then enter a spin with a nose-low attitude. The airplane subsequently impacted a rice field adjacent to the field being treated. PERSONNEL INFORMATION The pilot, age 27, held a commercial pilot certificate with an airplane single-engine land rating. On March 28, 2017, he was issued a second-class medical certificate with no limitations. The pilot was 73 inches tall and weighed 256 lbs at the time of his last exam. On his medical certificate application, the pilot reported 4,188 total hours of flight experience, 320 hours of which were flown during the previous 6 months. On an insurance application dated August 5, 2015, the pilot reported 1,750 hours flown in agricultural airplanes, 150 hours of which were flown in turbine engine-powered agricultural airplanes. The pilot's logbooks were not made available during the investigation. AIRCRAFT INFORMATION The single-engine, low-wing, conventional-geared airplane was equipped with a Pratt and Whitney PT6A-60AG turbo-prop engine. The Hobbs hour meter was destroyed in the accident; therefore, the engine's time-in-service could not be determined. The airplane's maintenance records were not made available during the investigation. WRECKAGE AND IMPACT INFORMATION The airplane impacted a flat, flooded rice field north of the field the pilot was treating. The rice was about 24 inches tall, and the water was about 8 inches deep. A strong smell of jet fuel existed at the site, and an area of the field showed damage consistent with fuel spray. The airplane was equipped for spreading granular materials, and small amounts of dry urea fertilizer were found in several locations at the accident site. The wreckage was found in an upright position, oriented toward the south. The forward fuselage was destroyed, and the wing leading edges were crushed aft. The engine, firewall, cowling, hopper components, and upper instrument panel were found about 75 ft away from the center of the wreckage with a ground scar extending from the primary impact point. All flight control surfaces were found in the wreckage. The elevator controls were continuous from the control stick to the elevator horns. The aileron controls were continuous except for fractures on both sides where the wings meet the fuselage. The right rudder cable was continuous to the right rudder horn. The left rudder cable had separated near the airplane's aft end. The lower end of the vertical fin and rudder were separated from the fuselage and were displaced to the right. Measurement of the flap actuator's extension indicated that the flaps were deflected about 11°. Engine examination found rotational contact signatures on its internal components. Examination of the recovered propeller blades and propeller hub revealed no indications that the propeller was in beta mode or reverse pitch. No evidence of preimpact anomalies of the engine, airframe, or propeller were found. MEDICAL AND PATHOLOGICAL INFORMATION The Arkansas State Medical Examiner, Little Rock, Arkansas, conducted an autopsy of the pilot and determined that the cause of death was "generalized blunt force injuries" and that contributing to the cause of death was "coronary artery disease." The autopsy revealed that the pilot had severe coronary artery disease with about 90 percent narrowing of the left anterior descending coronary artery. The pilot also had mild interstitial and perivascular fibrosis, which is scar tissue in the heart muscle and tissue around the blood vessels that can predispose an individual to sudden cardiac dysrhythmias, which, if prolonged, can cause death. The FAA's Bioaeronautical Sciences Research Laboratory, Oklahoma City, Oklahoma, conducted toxicological testing on specimens from the pilot. The testing was negative for ethanol, carbon monoxide, and tested-for-drugs. On his last FAA medical examination, the pilot stated that he did not have any medical concerns and that he did not use any medications. The pilot's family was not aware of that the pilot had any medical issues. ADDITONAL INFORMATION A SATLOC, which is an aerial guidance system that allows agricultural applicators to view flight information, such as spray and waypoints, was recovered from the wreckage and sent to National Transportation Safety Board's Vehicle Recorder Division for download and readout. SATLOC data revealed that the accident occurred on the third trip to treat a field south of the accident site. The first flight to the field consisted of an orbit to the south of the field being treated, followed by six passes in the field. The second flight consisted of 9 1/2 passes in the field. Each of the passes were in a north-south or south-north direction with left-turning "racetrack" patterns. During these patterns, the seven turns made on the north side of the field were on average about 18 seconds long. The third flight consisted of a single pass from south to north. It is uncertain how many additional passes were made before the accident occurred. From the end of the GPS recording, about four passes remained to finish treating the field.
The pilot's incapacitation due to a cardiac event, which resulted in a loss of airplane control.
Source: NTSB Aviation Accident Database
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