Greengrass persuaded a number of government workers -- including Ben Sliney, head of air traffic control in Herndon, Va. -- to play themselves. Sliney is key because he is the bureaucrat who boldly decided to halt all flights in America because the country was at war, when he didn't know there were four planes involved and couldn't get good answers from the military.
This is a valuable perspective that debunks the belief that warnings of the attacks were loud and clear or that officials should have jumped to action the minute American Flight 11 hit one of the World Trade Center towers. At the time and on the scene, decisionmakers didn't have the information or ability to respond surgically. See the military planes flying over the ocean, where they were least needed.
The attacks were simply too quick. The 9-11 commission report concluded that minutes after the Flight 93 crash, President Bush authorized a shooting down of American planes, if necessary. But the brass didn't pass on the order, lest American pilots shoot down the wrong plane. The movie makes it clear how the wrong response might have followed.
One morning, 33 passengers and seven crewmembers boarded a plane expecting a simple, if tedious, cross-country flight. Instead, they walked into bloody history, and they did the best they could. The Sept. 11 panel found that their "actions saved the lives of countless others." It is not too soon to relive that day.