As Katrina built up steam, the warnings were clear.
This is going to be one of the strongest hurricanes ever to hit the United States, said National Hurricane Center Director Max Mayfield Aug. 28 as the storm approached.
One National Weather Service meteorologist even dispatched a prophetic Katrina bulletin, warning: "Most of the area will be uninhabitable for weeks."
Yet despite that dire of a warning, to a lot of people it seemed as if few in government had been listening.
"I can't get out. How am I [sic] get out?" said one man after New Orleans flooded.
"I'm scared, I'm scared. I don't know what's going to happen," echoed another woman.
So what went wrong in those first crucial days?
The evacuation
Thousands were stranded for days at the Superdome and at the New Orleans Convention Center, all in squalid conditions.
They are just left behind," NBC News cameraman Tony Zumbado reported on Sept. 1, 2005. "There's nothing offered to them. No water, no ice. It's getting very crazy in there, and very, very dangerous.
Among the causes: A delay by state and city officials in ordering a mandatory evacuation for New Orleans until 19 hours before landfall. A Senate investigation found the delay caused "preventable deaths" and "great suffering."
Another cause: A lack of buses. Louisiana Gov. Kathleen Blanco waited until after the storm hit to ask FEMA for buses. They didn't begin to arrive until four days after landfall.
Meanwhile, dozens of city-owned school buses that could have been used for rescue were trapped under water.
The levees
The second big failure was the levees. Three hundred fifty miles of levees and floodwalls were supposed to protect New Orleans, but they failed and allowed the Ninth Ward and so much more to wash away.
"Over 80 percent of the city is flooded," I reported on Aug. 30, 2005. "They are dealing with some of the worst of human conditions on the planet, certainly in the United States."
At first, the U.S. Army Corps of Engineers insisted it was not its fault.
"The intensity of this storm simply exceeded the design capacity of this levee," said Gen. Carl Strock on Sept. 2, 2005.
But the experts started to investigate, and the facts began to turn up major flaws in the design, including weak soil that designers had ignored.
Months later, the Army Corps was forced to admit it had let the city down.
"We do take accountability," said Gen. Strock at a press conference on June 1, 2006.
Government mismanagement
The third devastating factor was government mismanagement. Acomplete breakdown in coordination.
FEMA had only one official inside the New Orleans Command Post when the storm hit.
FEMA Director Michael Brown seemed tragically out of touch.
I asked him where all the aid was on “Nightly News” Sept. 1.
"The federal government just learned about those people today," said Brown.
Gov. Blanco admitted that she waited too long to request federal troops.
"I really need to call for the military," she told an aide on Aug. 31, 2005. "And I should have started that in the first call."
In the end, too few accepted the blame.
"Who bears the responsibility for this?" I asked Brown on Feb. 28, 2006.
"Well, I think that we all do. If we don't learn from this, then shame on us."