On June 20, 2024, at 1258 mountain daylight time, an Air Tractor AT-802, N802AT, and an Air Tractor AT-502B, N581TW, were destroyed when they were involved in a mid-air 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 a 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. They began operations about 0530 and each airplane had conducted multiple aerial application flights within 10 miles of AOC prior to the accident. The AT-502B departed AOC about 1230 with 400 gallons of a fungicide and insecticide mixture to be applied to wheat. The AT-802 departed AOC about 1245 with full fuel tanks and 575 gallons of insecticide to be applied to potatoes. Aerial application data for the AT-802 was obtained from a recovered iPad utilizing the AgPilotX application. The data showed the AT-802 was applying chemicals to potato fields no.10 and no. 11 north of US Highway 26. Field no. 11 was immediately adjacent to the highway and field no.10 was adjacent to field no. 11 to the northwest. The application data showed the AT-802 was applying chemicals to both fields making northwest and southeast passes (figure 1). The AT-802 was not equipped with ADS-B equipment. The AT-502B was equipped with ABS-B. Preliminary ADS-B derived data provided by a commercially available source showed the flight path began with the AT-502B flying a west and then an east track about 5 miles northwest of AOC over wheat fields no. 2 and no.3. The airplane then flew to the southeast before turning to the south, where it overflew the fields which the AT-802 was working (figure 1). The last ADS-B target for the AT-502B was north of the accident site, over US Highway 26. 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 towards 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 left turn to avoid the first airplane before they collided. The accident site encompassed three areas of wreckage, the main wreckage of the two airplanes and a debris field located about midway between the two fuselages. Both airplanes and the associated debris came to rest on flat, sagebrush covered terrain south of US Highway 26. The main wreckage of the AT-802 was located about 450 feet south of the highway, with a debris path oriented on a magnetic heading of about 220° heading. The main wreckage of the AT-502B was located about 1,900 ft south of the highway and about 1,600 ft southeast of the AT-802. The debris path of the AT502 was oriented on a magnetic heading of about 105°. Portions of both airplanes’ right wings were located within the debris field between the two main wreckages. Figure 1 – Preliminary ADS-B Flight Path and Operation Area Overview