The wind shift and intensity was so sudden that the elite Hotshots, who were making their way toward a nearby ranch, reported after a half hour of radio silence that "our escape route has been cut off." They were overwhelmed by flames in chaparral brush within two minutes of making that frantic radio call at 4:42 pm, the investigators said.
Only the crew's lookout, Brendan "Donut" McDonough, 21, survived because he was away from the group and was sent to safer ground when he reached his "trigger point" as the fire intensified.
In the hour before the Hotshots made the emergency call after descending from a "black" burned out safe zone into a box canyon, the severe weather had grounded some airtankers and closed the Prescott airport. Another nearby airport ran out of retardant.
The Arizona serious accident report disclosed a new fact that few state or federal officials knew at the time or in the months since -- one DC-10 "very large airtanker," or "VLAT," was in the vicinity of Yarnell when top hotshot Eric Marsh radioed that their situation was desperate.
"I did not realize they had a VLAT on scene," Chief Willis told ABC News on Monday.
The forestry division spokesman in Arizona, Jim Paxon, also said he was surprised to learn about the DC-10 VLAT on Saturday when the report was released.
Neither U.S. Forest Service Chief Tom Tidwell, his aviation director Tom Harbour or any other agency officials interviewed or contacted by ABC News since the June 30 deaths disclosed that there was a DC-10 over Yarnell when the search began for the missing hotshot crew.
Willis was in Yarnell when his men perished on the mountain, but was not in contact with the crew and didn't see the DC-10, which was at times seven miles away amid a sky filled with smoke. "I think everyone wishes someone knew exactly where [the Granite Mountain Hotshots] were so possibly some retardant could have been used in a strategic location," he said Monday.
At 4:42 pm, chainsaws clearing brush could be heard on the radio when Marsh said they had no escape and were deploying personal fire shelters.
"We are preparing a deployment site and we are burning out around ourselves in the brush and I'll give you a call when we are under the sh— the shelters," Marsh yelled.
A spotter plane responded, "K, we're gonna bring you the VLAT okay."
Marsh never responded.
The spotter plane made seven passes over the fire looking for the Hotshots in their yellow firefighting jackets as the DC-10 VLAT orbited the fire ready to drop more than 11,000 gallons of retardant – which is meant to block a fire's advance, not douse it.
But thick smoke and flames blanketed the mountainside, the report said. It took almost two hours until a paramedic on the ground finally located their deployment site -- and reported 19 fatalities.
10 Tanker owner Rick Hatton said in an interview that it's still unclear how the severe weather that afternoon affected his two converted passenger jets' operations, but he confirmed one of the DC-10s was flying near Yarnell ready to drop retardant when the crisis occurred.
"My captain was right overhead when those guys got killed," Hatton told ABC News on Saturday.
Investigators said they could not determine why the hotshots moved from "the black," the safe burned area where they last had checked in over radios, and down into the box canyon where their escape route to the nearby ranch was suddenly cut off.
"I believe there were circumstances that occurred and decisions that were made that we do not have facts on that contributed to their deaths," Chief Willis told ABC News. "We will never know what they were thinking or their decision process."