Preliminary report reveals one of the SEATs involved in the July 30 mid-air collision had retardant on windshield

Two pilots were killed July 30, 2020 at the Bishop Fire in southeast Nevada

NTSB graphic mid-air crash air tanker
NTSB graphic of the last flights of N1558W (Tanker 824) and N8510M (Tanker 866).

A preliminary report released by the National Transportation Safety Board revealed that one of the two Single Engine Air Tankers (SEAT) that collided and crashed July 30, 2020 had fire retardant on the windshield. Both pilots of the aircraft, the only personnel on board, were killed while assisting firefighters on the Bishop Fire in southeast Nevada.

The investigators found that the tankers were working in tandem with one close behind the other. After the following aircraft got retardant on the windshield it made a rapid climb then suddenly turned left and collided with the other.

Both of the SEATs were operated by M&M Air Services out of Beaumont, Texas but the names of the two pilots have not been released. The aircraft were made by Air Tractor, model AT-802A; N8510M (Tanker 866) and N1558W (Tanker 824).

Below is the complete text of the preliminary NTSB report:


On July 30, 2020, about 1256 Pacific daylight time, 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 use firefighting flights.

The airplanes were functioning as single-engine airtankers (SEATs) for the Bureau of Land Management providing aerial firefighting services at the time of the accident. According to automatic dependent surveillance broadcast data (ADS-B) and witness statements, the airplanes departed Mesquite, Nevada as a flight of two about 1225 to deploy their third load of fire retardant that day. ADS-B data showed that N8510M was in lead and N1558W was in trail as they flew northeast towards a designated fire traffic area in a climb. At 1252:47, the pilot of N8510M started a descent from 7,100 ft msl accompanied by a slight right turn to the north and then he turned west about 15 seconds later. N1558W followed the movements of N8510M from about 1,500 ft behind him. About this time a lead airplane had begun to escort the flight of two SEATs 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 when they leveled out, N1558W was about 500 ft in trail of and 100 ft below N8510M. The data showed that the airplanes were in a descent about 400 ft above ground level when the ADS-B data ceased temporarily at 1955:23 for N8510M and at 1955:28 for N1558W. The data for N8510M resumed at 1255:38 and showed the airplane in a climb along a southeast heading. The track 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.

Video recorded by a ground witness captured both airplanes seconds before their collision, 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. Witnesses in 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. 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.

Postaccident examination of the accident site revealed that N8510M was mostly consumed by a postimpact fire. The wings and forward fuselage of N1558W came to rest about 315 ft beyond N8510M and did not burn. The tail section of N1558W, was located about 450 ft northwest of the forward fuselage and was partially damaged by postimpact fire.

The wreckages were retained for further examination.


Red Canyon Fire
File photo of air tanker 866 (N8510M) dropping on the Red Canyon Fire in South Dakota July 9, 2016. Photo by Bill Gabbert.
Tanker 824 (N1558W)
File photo of tanker 824 (N1558W) at Boise, July 19, 2014. Photo by Bill Gabbert.

Thanks and a tip of the hat go out to Dale.

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5 thoughts on “Preliminary report reveals one of the SEATs involved in the July 30 mid-air collision had retardant on windshield”

  1. Like Bill, I’ve photographed (along with crewing and flying in) an aircraft that was later involved in a fatal crash. When I heard about that (B-17G) accident (slim on many details) I recalled having thought those aircraft should have “protected” cameras recording every flight, even a form of ‘black box’ (We attached exterior lipstick cameras on past flights, achieving excellent video). The added expense is well worth it, including hopefully preventing a similar event. I believe this equipment should be standard on aerial firefighting aircraft.

    May these pilots rest in peace.

  2. Without comment on this specific mishap (which I feel is premature), I’ve flown SEATs for over 15 seasons, and like many SEAT pilots, have had retardant on the windscreen. For various reasons, it happens.

    SEATs frequently do series drops, with following one another to the drop, and tagging on to the preceding aircraft’s retardant. It enhances accuracy, makes the flight more efficient by putting everyone on a single lead-in, reducing costs, time, and allowing accurate, real-time adjustments for wind, drop length and terrain, etc. It’s done all the time. There are significant advantages, and there are also disadvantages to the technique. Among them are wake turbulence from the aircraft ahead; the loss of lift can be significant to an airplane that’s already heavy and operating at the weight limits for it’s type, even flying behind another SEAT or a lead. Consequently, remaining at the same altitude or slightly above the preceding aircraft is wise.

    Even at idle on a downhill run, different airframes will exhibit more or less drag, and it’s possible to run out of ways to slow the airplane down, resulting in an increasing closure. This isn’t unique to SEATs; it can happen between any aircraft over the fire, including leads and tankers. Having a pre–briefing and a plan for the drop to cover the contingency, and communication during the closure, is critical to preventing a mishap. There have been times when I couldn’t get a word in, due to a running commentary by the lead. There have been times when the aircraft ahead released high, resulting in my being below their flight path or descending through it. There are also times when unpredictable winds may alter the retardant path, including causing it to climb, or drift into the trailing aircraft that’s flying an “offset.” Terrain can limit options for responding to this situation, and it’s also possible that one may have to exit the drop without jettisoning the load, limiting performance and maneuvering options.

    In nearly all cases, a lead will pre-brief the exit (eg, “you exit straight out, I’ll be in a climbing left turn,” etc). The same understanding should exist between aircraft on the drop.

    I have been on a number of trail drops in which the lead did not descend to the altitude of the SEATs, with the SEATs descending through the lead wake, or staying high to avoid needing to deal with the wake; that also complicates the retardant location. Because a drop is often a descent to the release point, level, then a climb, each subsequent aircraft tagging onto the former drop may be descending to the end point of the previous line; the aircraft ahead is climbing. A tank trailing retardant may get the trailing airplane, as may wind rotors or eddy’s, retardant which hangs and doesn’t fall, etc.

    Like everyone in the community, I’m saddened by this event, as with each tragedy and mishap that occurs in fire operations. Condolences to M&M and to the families, and friends who are affected: we’re all affected, we’re all tools in the same box. It’s easy to stand afar and critique; I’d rather remember, and look for lessons to prevent the next, and despite what mistakes may have occurred, to remember those who ultimately gave all, on the job. There’s a lot to be said yet, but in time as the details emerge.

    1. Doug – you know if there are standards for lateral and vertical SEAT separation when they do series drops, or is it up to the discretion of the pilots?

      1. Steve,

        I’m not aware of specific values for separation, so far as a vertical separation or distance in trail.

        I have flown both close and fairly distant in trail separation from other aircraft on drops; when flying a large air tanker, I have been close enough to a lead that I have lost sight of the lead, as separation changed going into the drop. Likewise, I’ve experienced the same thing in trail of another SEAT. Particularly during a downhill run, different aircraft, even those of the same aircraft type, will accelerate differently, even at idle power.

        In the case of a SEAT drop, a large speed range is not available, neither is the power or ability to make rapid changes to catch up with traffic ahead. One must stay fairly close, whether it’s another SEAT, or a lead, or there will be a loss of accuracy. a lead too far ahead makes it harder to judge the drop point the lead calls, due to parallax, if the drop point isn’t a specific geographic feature (tag and extend off a retardant line, start at a boulder or tree, etc). If the preceding aircraft is another SEAT, accuracy in tagging and extending the prior aircraft’s retardant line is enhanced by being reasonably close, yet far enough to account for changes needed due to wind drift, etc.

        The distances required really depend on the drop circumstance and conditions, such that I believe it would be difficult to set specific standards. Additionally, there is no equipment on board the SEAT to set vertical separation, other than a barometric altimeter. With SEAT drop height at 60+ feet, the aircraft will be close enough to the terrain at the time of the drop that eyes are outside the cockpit; everything about a SEAT drop involves judgement and eyeball trigonometry.

        Not related to your question, but a thought occurred as I considered this mishap, and really all mishaps. It was a quote from a groundschool I attended. “I’m not sure of the original author.

        “Whenever we talk about a crew who has been killed in an aircraft accident, we should keep one thing in mind. They called upon the sum of their knowledge and made a judgement. They believed so strongly in their decision that they knowingly bet their lives on it. That their judgement was faulty is a tragedy, not stupidity. Every instructor, supervisor, and contemporary who ever spoke to them had an opportunity to influence their judgement, so a little bit o fall of us goes with every crew or pilot we lose.”

        It’s evident that the trail airplane in this drop had a loss of forward vision from the preceding aircraft. The preliminary states that the preceding aircraft made a shallow exit. The trailing aircraft dropped and had a more rapid climb. I can certainly see getting rid of the load and climbing quickly to ensure terrain separation. The natural transition is to looking out the side of the cockpit. The SEAT is equipped with a resorvoir for windshield wash, and a wiper, which would normally be applied some time before landing; between ash and bugs and potential retardant, often that turns into a smeared mess; I’ve landed more than once with forward vision obscured. My point is that loss of forward vision might necessitate a more rapid climb, but wouldn’t by itself be considered dire. The initial assumption, if in trail, would probably be that the preceding aircraft was ahead to begin with, and should still be ahead. It’s a case such as this when an escape plan for separation would be useful. The most limited aircraft, however, would be the one with obscured vision, and the immediate concern, flying the aircraft, rather than radio calls or separation.

        There’s often ample talk over the fire verifying that aircraft have each other in sight when entering, exiting, and when cleared down for the drop. On exit, it’s common to make a call verifying the exit, verifying in sight, etc. It may be that this event happened with the intent to do so, but too soon after the drop, while the pilots were making their initial actions, cleaning up or reconfiguring, making safe, etc, and before the chance to call arose (aviate, navigate, communicate).

        SEATs don’t have TCAS, unlike some other aircraft on the fire.

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