Evidence suggests the crew closest to the explosion knew what was about to happen but had little time to react and no way to stop it.
At 2:59 p.m., the operator manually disconnected the cutting machine, a two-step process that investigators say shows he knew something serious was happening.
When dust started billowing from the mine, dispatcher Adam Jenkins frantically called underground, reaching only one crew.
"I hollered and hollered and hollered — just, you know, praying and hoping that someone would answer me," he told investigators, "and it never happened."
Blake, meanwhile, struggled in the darkness to save his crew, pulling Woods and seven other men from a shuttle car and putting emergency air packs on all but one, whose device was missing.
"They all had pulse," he said.
Blake checked them a few minutes later.
"Everybody had a pulse but one man."
Then he decided to leave them — "the hardest thing I ever done" — to get help.
On his way, he met Massey employees who had raced into the mine to help. One was an emergency medical technician, and together in darkness, they prayed.
The report reveals that 19 of the miners died of carbon monoxide poisoning, although several also suffered traumatic injuries in the blast.
Though critics often claim Massey puts production over safety, it's a charge the company vigorously denies.
But the report's narrative delivers a scathing assessment of Massey, saying deviance from the industry's accepted safety standards was the norm.
The report says the mine was a place where foremen improvised on a regular basis to give their crews enough fresh air, where anyone who dared challenge authority was threatened with firing, and where the only thing that mattered was made crystal-clear in a single practice — calls to the surface with production reports every 30 minutes for company executives.
Although the blast has been widely viewed as a single event, the report says it was actually a chain reaction that lasted from one to three minutes, starting at 3:01 p.m. As coal dust become airborne, it provided more fuel, allowing the blast to continue propagating "like a line of gunpowder," forward in multiple directions, "obliterating everything in its path."
In January, the federal Mine Safety and Health Administration said it suspected the blast began with a spark from the cutting head of a mining machine, which had poorly maintained and plugged water sprayers that failed to douse the flames.
McAteer's investigators agreed.
They also reject Massey's claim that a sudden inundation of methane or natural gas from a floor crack caused the explosion when it overwhelmed all safety systems.
"Evidence found during the investigation does not suggest a force of this magnitude," the report says.
The investigators also concluded the mine's ventilation system had been compromised, in part by flooding in tunnels leading to a fan positioned to suck air through the mine, but also by leaky airlock doors that had been propped open and other missing air controls.
Upper Big Branch was cited 64 times for ventilation violations in 2009.
Massey has spent moths blaming the federal government for the blast, claiming that changes MSHA ordered to its ventilation plan only contributed to the problems.
The independent investigators found no evidence to support those claims.
Nor did they find any records showing Massey complained to MSHA.
The mine about 50 miles south of Charleston hasn't operated since the explosion. Massey has proposed sealing the mine, but details still need to be worked out with MSHA.
Associated Press reporter Lawrence Messina contributed to this report. Huber reported from Charleston, W.Va.