Accident
On July 30, 2020, about 1256 Pacific daylight time, two Air Tractor AT-802A airplanes, N8510M and N1558W, were destroyed in a midair collision near Elgin, Nevada. The pilots of both aircraft sustained fatal injuries. The airplanes were operating as single engine airtankers (SEATs) under contract to the U.S. Department of the Interior, Bureau of Land Management (BLM) for wildland fire suppression.
The SEATs had been dispatched to a wildland fire at about 0900 for their first retardant drop and had completed two uneventful flights in the fire traffic area (FTA) before the accident flight. Automatic dependent surveillance-broadcast (ADS-B) data indicated that the airplanes departed Mesquite, Nevada, as a flight of two about 1225 to deliver their third load of fire retardant. N8510M was in lead and N1558W was in trail as they flew northeast toward the FTA in a climb.
An air attack airplane was providing aerial reconnaissance at 10,000 ft mean sea level (msl), and a lead plane was operating at about 7,500 ft msl, supporting air attack by leading airtankers to the retardant line. When the SEATs were about 12 nautical miles from the FTA, they checked in with air attack, who briefed and cleared them into the FTA. The pilot of the lead plane planned to join with N8510M and N1558W on the downwind leg of the deployment pattern at 6,000 ft msl. The exit procedure briefed for the SEAT pilots required them to turn left to the northeast and climb to 6,500 ft msl after the drop, while the lead plane was to exit straight out.
At 1252:47, N8510M started a descent from 7,100 ft msl with a slight right turn to the north, followed by a turn to the west about 15 seconds later. N1558W followed the movements of N8510M from about 1,500 ft behind. The lead plane had begun escorting the SEATs to the drop area. At 1254:37, N8510M turned left to a southeast heading and descended from about 6,000 ft msl, with N1558W still about 1,500 ft in trail. N1558W began a turn to the southeast a few seconds later and descended from 6,100 ft msl. After leveling out, it was about 500 ft in trail and 100 ft below N8510M on a heading of about 145° magnetic. ADS-B data showed both aircraft descending at about 400 ft above ground level when data temporarily ceased (at 1255:23 for N8510M and 5 seconds later for N1558W). Data resumed for N8510M at 1255:38, showing it climbing on a southeast heading. Data for N1558W resumed at 1255:45, showing it climbing on a similar heading about 70 ft in trail and 125 ft below N8510M.
An air attack pilot reported monitoring a helicopter returning from a recon mission and the retardant drops when the accident occurred. He stated that the SEATs were in a flight of two behind the lead plane. After the first SEAT (N8510M) dropped its retardant load, the second SEAT (N1558W) began to encroach on the first at a rapid rate. Video from a ground witness showed N8510M descend to low altitude, deploy retardant, and then immediately begin a shallow climb. N1558W followed very close in trail, then deployed retardant and began a rapid climb. The video did not capture the collision.
Witnesses in a nearby firefighting aircraft stated they heard the pilot of N1558W announce that he had retardant on his windshield and was initiating a go-around. The air tactical supervisor reported hearing the pilot say he was "pickling" his load (emergency release). Witnesses on the ground observed that as N1558W climbed, it suddenly began a left turn and collided with N8510M. Both aircraft then descended rapidly to the ground.
Aircraft and Pilots
The government contract task order for SEAT flight services ran from June 3, 2020, through August 31, 2020, and included provisions for a primary pilot for each airplane. Both pilots were qualified level 1 SEAT pilots. The pilot of N8510M reported about 370 total flight hours in airtanker/dispensing operations; his most recent pilot carding was issued April 6, 2020. The pilot of N1558W reported about 1,762 total flight hours in airtanker/dispensing operations; his most recent carding was issued April 21, 2020.
According to the operator, the pilot of N1558W performed agricultural application work when fire season was inactive. The operator occasionally received complaints about this pilot, but none were deemed worthy of relieving him of his job. In spring 2020, a forestry company in Florida reported the pilot flying too close to a sawmill. Additionally, a third-hand complaint indicated the pilot flew too close to a lead airplane during a ferry flight; the operator notified the pilot, who said he would maintain a safe distance from the lead airplane in future flights.
Wreckage
The wreckage of N8510M was located on a slope at about 4,222 ft msl and was mostly consumed by postcrash fire. The wreckage of N1558W was in a valley about 315 ft southeast of N8510M. All major structure and control surfaces of both aircraft were accounted for at their accident sites. The main wreckage of N1558W comprised the forward fuselage and left wing oriented on a heading of 127° true and was not damaged by fire. The aft fuselage and empennage were about 450 ft northwest of the forward fuselage and partially damaged by postimpact fire.
Inspection of N8510M showed four of five propeller blades bent, intact, and attached to the hub; one blade had separated inboard and at the tip. Multiple blades displayed leading edge gouges, trailing edge tears, and yellow paint transfer marks. N1558W exhibited multiple black rubber transfer marks on the left-wing flap, upper left-wing skin, and left fuselage near the cockpit step. The three upper left engine mount tubes were fractured, two showing mechanical crushing damage. The oil cooler had a mechanical cut with deformation outward. The rinse tank shelf had two parallel mechanical cuts oriented about 110° right of the airplane’s longitudinal axis, with edges deformed and smeared downward. Matching cuts were found in the upper cowling. No pre-collision anomalies were noted with either airplane.
Additional Information
The lead airplane was applying PHOS-CHEK LC95A-Fx fire retardant, described as containing an enhanced fugitive coloring agent to improve visibility. The manufacturer reported that the retardant’s coloring makes it opaque, which would block a pilot’s vision if it contacted the windshield.
Interagency fire suppression procedures are set by the National Wildfire Coordinating Group (NWCG). The PMS505 manual at the time stated that trailing aircraft are responsible for separation between their aircraft and the aircraft they are following.
The contract required the operator to establish and implement initial and recurrent training covering subjects such as aircraft separation, drop procedures, emergency dump, and emergency procedures. Both pilots completed annual company training on March 12, 2020, and attended the National Aerial Firefighter Academy (NAFA) 2 Refresher course on January 10-11, 2020. The pilot of N8510M completed Interagency Aviation Training (IAT) in March 2020, and the pilot of N1558W completed IAT in April 2020. NAFA training is designed for personnel directly involved in aerial retardant and water delivery. The course organizer stated that the NAFA II Refresher course did not include overrun procedures that year but did discuss go-around procedures, which included flying the briefed initial exit, reconfiguring the aircraft, reporting the go-around, climbing to 1,000 ft AGL maneuvering altitude, and not climbing to orbit altitude to avoid conflict with other aircraft.