WPR24FA201

Two airplanes, an Air Tractor AT-502B and an Air Tractor AT-802, owned and dispatched by the same operator, were conducting aerial application operations from the same airport and in the same geographic area when they collided in flight during day visual meteorological conditions. Both airplanes had been dispatched from their base of operations to an airport near the operating area the morning of the accident, and each pilot was tasked to apply products to different agricultural fields. After leaving the fields northwest of the airport, the AT-502B maneuvered south toward fields assigned to the AT-802. These fields were west of both the airport and the other fields assigned to the AT-502B. The AT-502B maneuvered to the south about the same time that the AT-802 departed the airport and flew west back toward its assigned fields. Both airplanes were flying at similar low altitudes above ground level. Two witnesses traveling westbound on a highway observed one airplane, likely the AT-502B, traveling from north to south over the highway at low altitude. They also observed a second airplane, likely the AT-802, traveling toward the first on a northerly heading. They said the southbound airplane appeared to make a left turn in front of the northbound airplane. The northbound airplane then appeared to make a hard right turn before they collided. Impact damage and debris field findings were consistent with each airplane impacting the other’s right side. According to operator personnel, the pilots discussed which fields each pilot would be responsible for, and they were aware of each other’s area of operations. Operator personnel also stated the company and pilots did not have formal deconfliction or communications plans, and that the pilots primarily used cell phone voice and text to communicate with each other and the ground crews. The last documented communication between the pilots occurred three hours before the accident. The AT-802 pilot’s toxicological testing indicated that he had used or been administered ketamine, fentanyl, and ondansetron. These are common postaccident treatment medications, and there is a strong possibility that they were administered to the pilot after the accident. If so, the toxicology results would not constitute evidence of pre-crash ketamine, fentanyl, or ondansetron use. Other detected substances (dextromethorphan and naproxen) are not typically impairing with appropriate use. Whether they were used to treat active symptoms of minor acute illness could not be determined. The AT-502B pilot had cardiovascular conditions, including coronary artery disease and diabetes, that were associated with increased risk of an impairing or incapacitating cardiovascular event, such as arrythmia, heart attack, or stroke. There is no autopsy evidence that such an event occurred, although such an event does not leave reliable autopsy evidence if it occurs just before death. Based on HbA1c values, the AT-502B pilot’s diabetes wasincompletely controlled at the time of his last FAA medical examination and remained incompletely controlled in the months before the accident. The fact that his medication-treated diabetes had been waived by the FAA indicates it is unlikely that significant medication side effects or long-term ocular or neurological complications of the disease had been identified as of that time. Symptoms such as fatigue or blurry vision may occur in incompletely controlled diabetes. Overall, the investigation could not determine whether the AT-502B pilot was experiencing impairing effects of his incompletely controlled diabetes, such as fatigue or blurry vision, at the time of the accident. Both pilots were required to use corrective lenses to meet vision standards at all required distances. The AT-802 pilot was likely wearing corrective lenses at the time of the accident. Investigators could not determine if the AT502B pilot was wearing corrective lenses at the time of the accident. The accident is consistent with both pilots failing to see and avoid each other in sufficient time to avoid a collision. However, the operation of both airplanes in the same geographic area increased the likelihood of a conflict between the two airplanes, the risks of which could have been reduced if the operator and pilots had developed and followed a formal deconfliction plan and the pilots had communicated their locations and intentions regularly during the flights. Both pilots likely had little or no situational awareness as to their proximity to the other airplane until immediately before impact.

The airplanes’ operator reported that they did not have formal communication or deconfliction plans for airplanes operating in the same geographical area. The pilots communicated primarily through phone calls and text messages during operations. The AT-802 pilot’s cell phone was recovered, and a review of the text and phone logs on scene showed the last communication between the pilots was a 36-second phone call at 0958 on the day of the accident. No records or reports of radio communication between the two pilots were discovered during the investigation. On June 21, 2024, the National Agricultural Aviation Association issued a Fly Safe message informing pilots of the importance of communication and planning when operating in the vicinity of other aircraft. On June 20, 2024, at 1255 mountain daylight time, an Air Tractor AT-802 airplane, N802TP, and an Air Tractor AT-502B airplane, N581TW, were both destroyed when they were involved in a midair collision near Arco, Idaho. The pilot of the AT-802 was seriously injured and the pilot of the AT-502B was fatally injured. Both airplanes were operated as Title 14 Code of Federal Regulations Part 137 aerial application flights. Both airplanes were owned by the same operator, and both pilots were employed by that same operator. According to the operator, both airplanes were operating from the Arco-Butte County Airport (AOC), Arco, Idaho, on the day of the accident. Both airplanes had been dispatched from their base of operations to AOC the morning of the accident, and each pilot was tasked to apply products to different agricultural fields. They began operations about 0530, and each airplane had conducted multiple aerial application flights within 10 miles of AOC before the accident. The AT-802 was not equipped with ADS-B equipment. Flightpath data for the AT-802 was obtained from a recovered personal electronic device running the AgPilotX guidance application. The data showed the AT-802 had been applying insecticide to fields north of US Highway 26 subjectively labeled by the operator as field nos. 10 and 11 (see figure). The application data showed the AT-802 had been applying chemicals to both fields, making northwest and southeast passes before returning to AOC about 1244. The AT-502B was equipped with ADS-B and an AgNAV navigation system. ADS-B-derived data provided by a commercially available source and data recovered from the onboard AgNAV unit each captured limited portions of the accident flight. The data showed the AT-502B flew west and east about 5 miles northwest of AOC over wheat fields subjectively labeled by the operator as field nos. 2 and 3 until a break in the data recording occurred at 12:51:47. Two additional ADS-B data points at 12:54:21 and 12:54:47 showed the AT-502B had departed the area of aerial application and flew, on a southeast heading, adjacent to the west side of the two fields the AT-802 had been operating over. The final ADS-B point placed the AT-502B about 0.7 milesnorthwest of its wreckage location about 12:54:47 (see figure). About 1253, the AT-802 departed from runway 24 at AOC, located about 3.5 miles east of the accident location, and flew southwest about 5,500 ft msl (170 ft agl) before turning northwest toward field nos. 10 and 11. The flightpath data ended about 12:54:47 when the airplane was at an altitude of about 5,540 ft msl. Two witnesses traveling westbound on US Highway 26 observed one airplane traveling from north to south over the highway at low altitude. They also observed a second airplane traveling toward the first on a northerly heading. They said the southbound airplane appeared to make a left turn in front of the northbound airplane. The northbound airplane then appeared to make a hard right turn before they collided. Figure. Airplane flightpaths and areas of operation. AT-502B Pilot An autopsy of the pilot was performed by the Ada County Coroner’s Office, as authorized by the Butte County Coroner’s Office. According to the autopsy report, the cause of death was blunt trauma. The pilot’s last aviation medical examination was on November 27, 2023. At that time, he reported a history of diabetes, treated with the prescription oral diabetes medications metformin and glipizide. His hemoglobin A1c (HbA1c) was documented as 8.5% as of 6 days earlier. He was issued a second-class medical certificate by Special Issuance, limited by a requirement to use corrective lenses to meet vision standards at all required distances, and not valid for any class after November 30, 2024. Investigators were unable to determine if the pilot was using corrective lenses at the time of the accident. The pilot’s last Authorization for Special Issuance (with diabetes treated with oral medication) was issued on March 2, 2023. The pilot’s autopsy identified coronary artery disease, with 80% narrowing of the right coronary artery, 30–40% narrowing of the left anterior descending coronary artery, and 30% narrowing of the left circumflex coronary artery by plaque. Both ventricles of the heart were described as dilated. The remainder of the autopsy, including visual examination of the heart, did not identify other significant natural disease. The pilot’s postmortem toxicological testing by the FAA Forensic Sciences Laboratory detected metformin and glipizide in cavity blood and urine. Urine glucose was 669 mg/dL; vitreous fluid was not available for testing. Blood HbA1c was 9.1%. Glucose is the main sugar that provides energy to the body. Blood glucose (commonly referred to as blood sugar) normally fluctuates throughout the day. With diabetes, the body has difficulty effectively using glucose for energy; one consequence of this is an abnormal increase in blood glucose. HbA1c is an indirect measure of a person’s average blood glucose over about the preceding 3 months. An HbA1c of 6.5% or higher diagnoses diabetes. For many adults with diabetes, recommended HbA1c is less than 7%. Urine glucose does not directly reflectblood glucose but may increase due to high blood glucose or altered kidney function. In postmortem urine, the FAA Forensic Sciences Laboratory considers glucose above 100 mg/dL to be abnormal. Glipizide is a prescription oral medication commonly used in the treatment of diabetes. Glipizide is not typically impairing but may pose some risk of causing low blood glucose, symptoms of which may adversely affect concentration and performance. Metformin is a prescription oral medication commonly used in the treatment of diabetes and prediabetes. Metformin is not typically impairing and poses little risk of causing significant low blood glucose. AT-802 Pilot The AT-802 pilot’s most recent aviation medical examination before the accident was on November 13, 2023. According to the FAA medical case review, the pilot did not report any current medical conditions of concern or any medication use. He was issued a second-class medical certificate limited by a requirement to use corrective lenses to meet vision standards at all required distances. Ground personnel stated with a high level of certainty that the pilot was wearing glasses on the day of the accident. The pilot communicated to investigators through a family member that he was wearing his prescription glasses at the time of the accident, but that he could not recall the accident or the days leading up to it. The FAA Forensic Sciences Laboratory performed toxicological testing of blood collected during the AT-802 pilot’s postaccident medical care. This testing detected ketamine, norketamine, fentanyl, ondansetron, dextromethorphan, dextrorphan, and naproxen. Ketamine is a potentially impairing anesthetic drug that may be used medicinally or recreationally. It is commonly administered during medical care after major traumatic injury. Norketamine is a metabolite of ketamine. Fentanyl is a potentially impairing opioid pain drug that may be used medicinally or recreationally. It is commonly administered during medical care after major traumatic injury. Ondansetron is a prescription anti-nausea medication that is not typically performance-impairing. One of its common uses in medical care after major traumatic injury is to help prevent nausea and vomiting caused by opioid administration. Current FAA guidance indicates that occasional use of ondansetron by otherwise-qualified pilots may be acceptable in some circumstances, subject to a post-dose wait time before flying. Dextromethorphan is a cough suppressant medication that is available without a prescription in a variety of cold and allergy products. It is not typically impairing at levels associated with appropriate medicinal use. FAA guidance indicates that pilots who use dextromethorphan should observe a waiting period for the drug to be cleared from circulation before flying. Dextrorphan is a metabolite of dextromethorphan. Naproxen is a non-steroidal anti-inflammatory drug widely available without a prescription for treatment of pain, inflammation,and fever. It is not typically impairing. Over-the-counter cold and fever products containing both naproxen and dextromethorphan are available. The accident site was located in a flat, grass- and sage-covered field about 3.5 miles southwest of AOC. The wreckage of the AT-802 was found upright in a sage field with no signs of fire or heat damage. A ground scar containing left wing tip pieces and outboard wing segments was found about 285 ft south of the main wreckage. A ground scar containing propeller blades was found about 65 ft north of the initial impact scar. The wreckage was oriented on a heading of 202° magnetic. The wreckage of the AT-502B was found inverted in a sage field with no signs of fire or heat damage. The nose and engine sections of the airplane were found bent aft underneath the fuselage. The wreckage was located about 1680 ft south of the AT-802. A ground scar containing left wing tip pieces was found about 250 ft northwest of the main wreckage. An additional ground scar containing propeller blades was found about 40 ft south of the initial impact scar. The wreckage was oriented on a heading of 175° magnetic. A debris field about 735 ft by 600 ft consisting of paint flakes, wing fragments, and empennage fragments from both airplanes was located about 600 ft southeast of the wreckage of the AT-802 and 625 ft northwest of the wreckage of the AT-502B. A segment of the outboard right wing of the AT-502B was found in the debris field with a portion of the aileron still attached. The right flap of the AT-502B was found in the debris field north of the right wing segment. The right horizontal stabilizer, right horizontal stabilizer V-Strut, rudder, and elevator were found in the debris field south of the right wing segment. Segment of right wing tip, right wing aileron, and outboard right wing of the AT-802 were found in the debris field. All flight control surfaces for both airplanes were located within the wreckage and debris field. Flight control continuity was established for both airplanes to the extent possible given the wreckage condition. All observed separations were consistent with overstress. The powerplant for the AT-802 remained with the forward fuselage wreckage. The engine was found with impact damage, with the propeller hub separated from the engine. The engine was equipped with a five-bladed, constant speed, fully reversable propeller. Four blades were found separated from the propeller hub near the initial ground impact point. The one blade that remained attached to the propeller hub was found bent toward the cambered side of the blade. The powerplant for the AT-502B remained with the forward fuselage wreckage. The engine was impact damaged and the propeller hub section was disconnected from the engine. The engine was equipped with a 3-bladed, constant speed, fully reversable propeller. One of the propeller blades was found attached to the propeller hub and was separated about half of the propeller length. The twosections of disconnected blades were found separated at the hub and were located in the ground scar leading to the main wreckage.