One of the questions posed by the report gets to the heart of firefighting culture, said Dick Mangan, a retired U.S. Forest Service safety official and consultant.
"'What would you do if you were told to do nothing?' That's really key," he said. "All wildland firefighters — for that matter all firefighters, all police officers, EMTs, ambulance drivers — we're all driven to do good and sometimes your ambition to do good, or what you think is good, overrides your training and experience and puts you in a very dangerous situation."
While the motivation of the Hotshots to leave the blackened area are unclear, investigators surmise that the crew may have been trying to reposition themselves so they could re-engage in the firefighting effort.
By this point, the fire had reached Yarnell and all other crews were helping with structure protection and evacuations. The fire was changing direction and surging in intensity and speed as smoked filled the air and ash rained down.
Andy Stahl, executive director of Forest Service Employees for Environmental Ethics, said it was the vulnerability of Yarnell that resulted in the firefighters putting their lives on the line. The thick chaparral around the town hadn't burned in nearly a half-century, drought had plagued the area and many homes weren't defendable.
"There should have been a trigger point sooner when they realized there's nothing we can do here, we cannot fight it," he said. "There's this conceit that somehow with our technology and air power we can conquer an energetic force that's on par with hydrogen bombs. It's just not true. It's a lie, and these guys paid for that lie with their lives."
Stahl said the first lesson involves the ability to better recognize whether firefighting efforts are making a difference. Had that question been asked early and often, he said the outcome may have been different.
"The firefighters from start to finish weren't making any progress, and I'm not talking about just the Granite Mountain crew," Stahl said. "No matter what they were throwing at this thing, they were not changing the outcome."
What is certain, the experts say, is that firefighters and commanders will be picking apart the investigation and reading between the lines of the report as they search for lessons from the Granite Mountain Hotshots.
"This is going to be looked at very hard for many years to come," Mangan said.
Felicia Fonseca in Prescott, Ariz., Michael Blood in Los Angeles, Hannah Dreier in Las Vegas and Michelle Price in Salt Lake City contributed to this report.