N1558W

HISTORY OF FLIGHTOn July 30, 2020, about 1256 Pacific daylight time (PDT), two Air Tractor AT-802A airplanes, N8510M and N1558W, were destroyed when they were involved in an accident near Elgin, Nevada. The pilots of both airplanes were fatally injured. The airplanes were operated as public aircraft firefighting flights.

The airplanes were operating as single engine airtankers (SEATs) under contract to the US Department of the Interior (DOI), Bureau of Land Management (BLM) at the time of the accident. The pilots were dispatched to a wildland fire about 0900 for their first drop.

Both SEAT airplanes were extending a fire retardant line as part of fire suppression efforts. They completed two uneventful flights in the fire traffic area (FTA) before the accident flight. Automatic dependent surveillance-broadcast (ADS-B) data showed that the airplanes departed Mesquite, Nevada, as a flight of two about 1225 to deploy their third load of fire retardant. The ADS-B data showed that 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 of the fire environment at 10,000 ft in the FTA while a lead plane was operating about 7,500 ft mean sea level (msl), supporting air attack by leading airtankers to the retardant line. When the SEATs were about 12 nm from the FTA, they checked in with air attack who briefed them and cleared them into the FTA. The pilot of the lead plane planned to join up with N8510M and N1558W on the downwind leg of the deployment pattern at 6,000 ft msl. The exit procedure that had been briefed for the pilots of N8510M and N1558W required them to turn left (to the northeast) and climb to 6,500 ft msl after the drop. The lead plane was required to exit straight out.

At 1252:47, the pilot of N8510M started a descent from 7,100 ft msl along with a slight right turn to the north followed by a turn to the west about 15 seconds later. The pilot of N1558W followed the movements of N8510M from about 1,500 ft behind. About this time, the lead plane had begun to escort N8510M and N1558W to their intended 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 but, upon leveling out, was about 500 ft in trail of and 100 ft below N8510M on a heading about 145° magnetic. The data showed that the airplanes were in a descent at an altitude of about 400 ft above ground level when the ADS-B data ceased temporarily (at 1255:23 for N8510M and 5 seconds later for N1558W). The data for N8510M resumed at 1255:38 and showed the airplane in a climb along a southeast heading. The data for N1558W resumed at 1255:45 and showed the airplane in a climb on a similar heading about 70 ft in trail and 125 ft below N8510M.

An air attack pilot reported that he was simultaneously monitoring a helicopter that was returning from a recon mission and the retardant drops when the accident occurred. He reported that the SEAT airplanes were in a flight of two behind the lead plane. After the first SEAT (N8510M) dropped its retardant load, the second SEAT airplane (N1558W) began to encroach on the first SEAT airplane at a rapid rate. Video recorded by a ground witness captured both airplanes during a portion of the flight, which showed N8510M descend to a low altitude, deploy fire retardant, and then immediately begin a shallow climb. The video showed N1558W following very close in trail of N8510M during this time. N1558W then deployed fire retardant and began a rapid climb. The video did not capture the collision.

Witnesses in a nearby firefighting aircraft stated that they heard the pilot of N1558W announce over the radio that he had retardant on his windshield and was initiating a go-around. The air tactical supervisor reported that he heard the pilot of N1558W state that he was “pickling” his load meaning that he intended to perform an emergency release of the load. According to witnesses on the ground, as N1558W climbed, it suddenly began a left turn and collided with N8510M. Both airplanes then descended rapidly to the ground.

Figure 1: Fire Traffic Area

Figure 2: Flight track of N1558W and N8510M

PERSONNEL INFORMATIONThe government contract task order to the operator was for SEAT flight services from June 3, 2020, through August 31, 2020. This order included provisions for a primary pilot for each of the two airplanes, one fuel service vehicle (FSV) per airplane, and a primary and relief driver for each FSV. According to the contract, Level 1 SEAT pilots required a flight evaluation with the DOI every 12 months. Additionally, Level 1 SEAT pilots were required to complete the National Aerial Firefighter Academy 2 (NAFA 2) or NAFA 2 refresher training and show written proof of their course attendance. According to the BLM, both pilots had attended the NAFA 2 refresher course in January 2020.

The pilots of both airplanes were qualified level 1 SEAT pilots. The pilot of N8510M completed his most recent DOI Interagency Airplane Pilot Evaluation Application on February 19, 2020. In the application he reported about 370 total flight hours in airtanker/dispensing operations. His most recent United States Department of Agriculture Interagency Pilot Qualification Card (carding) was issued on April 6, 2020.

The pilot of N1558W had completed his most recent DOI Interagency Airplane Pilot Evaluation Application on March 1, 2020. In the application he reported about 1,762 total flight hours in airtanker/dispensing operations. His most recent carding was issued on April 21, 2020.

N1558W Pilot Flying History

According to the operator, the pilot performed agricultural application work for his company when the fire season was not active. The operator stated that he would receive a complaint about the pilot “every now and again,” but added that none of the comments were worthy of relieving the pilot of his job. Of the most recent complaints, one was reported by a forestry company in Florida in spring 2020 about the pilot flying too close to a sawmill. Subsequently, also in spring 2020, the operator received a third-hand complaint that the pilot had flown too close to a lead airplane during a ferry flight. The operator notified the pilot of the complaint, and the pilot informed his boss that he would remain a safe distance from the lead airplane during future flights.

WRECKAGE AND IMPACT INFORMATIONThe wreckage of N8510M was located on a slope at an elevation about 4,222 ft msl and was mostly consumed by postcrash fire. The wreckage of N1558W was located in a valley about 315 ft southeast of N8510M. All major structure and control surfaces of N8510M and N1558W were accounted for at their accident sites. The N1558W main wreckage was comprised of the forward fuselage and left wing oriented on a heading of 127° true and it was not damaged by fire. The aft fuselage and empennage section of N1558W was located about 450 ft northwest of the forward fuselage and was partially damaged by postimpact fire.

Figure 3: Flight track and accident sites

N8510M

Four of the five propeller blades were bent, intact and attached to the propeller hub. One propeller blade remained attached to the hub but had separated inboard and again at the blade tip. The blade tips to the four intact blades were all partially separated or curled. Three propeller blades displayed leading edge gouges and one propeller blade exhibited a tear in the trailing edge. Another of the propeller blades had semi-circular impact impressions in the leading edge. Two of the propeller blades had yellow paint transfer marks on their aft faces.

N1558W

The wreckage of N1558W exhibited multiple black rubber transfer marks that spanned from a moderate mark at the left-wing flap, a light mark on the upper left-wing skin, and a heavy mark on the left fuselage near the top of the cockpit step.

The three upper left engine mount tubes were all fractured and two of the tubes had mechanical crushing damage on the inboard sides adjacent to the fractures. The oil cooler displayed a mechanical cut through the unit with deformation in the outboard direction. Further, the rinse tank shelf, which is normally located between the left and right upper engine mount tubes, exhibited two parallel mechanical cuts. These cuts were oriented about 110° right of the airplane’s longitudinal axis and the edges were deformed and smeared downward. There were two matching mechanical cuts in the upper cowling normally installed above the shelf.

No pre-collision anomalies were noted with either airplane.

ADDITIONAL INFORMATIONRetardant Discussion

The lead airplane was applying the fire retardant, PHOS-CHEK LC95A-Fx series, which is used for wildland fire control in forest, bush and grassland fuels. The product sheet stated that the retardant contains “an enhanced fugitive coloring agent to improve visibility.” It is designed for fixed wing airtankers including SEATS, helicopter buckets, and ground engines.

The manufacturer reported that the retardant’s coloring makes it opaque, which would block a pilot’s vision if it came into contact with a windshield.

National Wildfire Coordinating Group Standards (NWCG) for Aerial Supervision Manual (PMS505)

Interagency fire suppression procedures and guidelines are set by the NWCG. At the time of the accident, PMS505, which provides guidelines for aerial firefighting, included a brief section dedicated to maintaining separation in SEAT operations:

There must be enough distance between aircraft to allow Aerial Supervision to convey updated directions to the air tanker considering the preceded drop or changes in objectives. The trailing aircraft are responsible for separation between their aircraft and the aircraft they are following.

Training

The contract stated that the operator would be respons...