Hard to fathom or forgive mostly forgotten facts:
-They had time to shoot down all the planes if there was a clear efficient protocol in place between civil aviation and the military. The maniacs should never have been able to get close.
-The WTC evacuation plans were putrid-thanx Guliani. That's on him but is never discussed. For example the doors to the roof that some tried to escape upwards through were locked after the '93 bombing, which prevented anyone trapped in upper floors from being rescued by helicopter.
-It's never come out who initially sent the firemen in and kept them in there too long.