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A view of a wildfire burning on Tuesday, Nov. 16, 2021 in an area south of Fish Creek Road in the Little Valley area on the south side of Estes Park. (Larimer County Sheriff Justin Smith)

Extreme turbulence probably caused a single-engine air tanker to fall from the sky as it fought a wildfire near Estes Park at night in 2021, killing the pilot, the National Transportation Safety Board ruled last month in a final report on the crash.

Marc “Thor” Olson died when the Air Tractor AT-802A he was flying went down as he battled the Kruger Rock fire on Nov. 16, 2021. 

The NTSB said its investigation found that the plane likely flew into severe or extreme turbulence caused by mountain wave rotor cloud activity, which resulted in loss of airplane control. Shortly before he crashed, Olson reported that conditions were turbulent and that he planned to return to the airport in Loveland. 

Rotor clouds form near mountains in windy conditions and can cause violent turbulence through updrafts and downdrafts. 


Olson was flying for CO Fire Aviation, a Fort Morgan-based company that was working to prove pilots wearing night-vision goggles could use planes to battle fires at night. Olson was a former military pilot who had extensive experience flying in the dark, including more than 1,000 hours flying with night-vision goggles, according to CO Fire Aviation owners Kyle Scott and Chris Doyle.

The NTSB said Olson was using night-vision goggles at the time of the crash. It’s very rare for firefighting aircraft to fly night missions and when it does happen it more typically is done using helicopters.

Federal investigators found no mechanical abnormalities with the plane.

“Video footage of the airplane showed the airplane’s wings rocking as it approached the

intended drop location. Two witnesses stated that they saw the airplane roll inverted,” the NTSB report said. “One of the witnesses, who was in radio communication with the pilot, stated that he did not hear the pilot report any problems with the airplane nor make any distress calls before the accident.”

The deadly crash appeared to be the first involving a firefighting aircraft in Colorado in two decades and the third fatal air disaster related to firefighting in Estes Park. While battling the 2002 Big Elk fire, two air tanker pilots died when their plane crashed as they hauled slurry to drop on the fire. About a week later, a helicopter pilot was killed fighting the same fire, when his Lama helicopter crashed.  

CO Fire Aviation said Friday in a statement to The Colorado Sun that it agrees with the NTSB report.

“CO Fire Aviation finds the NTSB report to be consistent with our own internal investigation and finding,” said Chris Doyle, chief pilot and chief operating officer of the business. “We lost a friend and great asset to CO Fire aviation and he is missed. Our thoughts, prayers and support continue for Thor’s wife, Ronda, and his family.”

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Jesse Paul

The Colorado Sun — Desk: 720-432-2229 Jesse Paul is a political reporter and editor at The Colorado Sun, covering the state legislature, Congress and local politics. He is...