There are undoubtedly those who will avoid this film as patriotic malarkey due to its subject matter: the passengers on the fourth hijacked airliner on September 11, 2001, who rose up against their captors before the plane could be crashed into whatever unknown target it was aiming for. This sort of attitude merely reflects the divisiveness in the US over the government's response to the 9/11 terrorist attacks, and ignores the primal horror and confusion that gripped the country on that day, and the passengers of United 93 even more so.
Though we now have had several years to form our opinions, theories, and suspicions about everything that happened that day, as well as the events that transpired before and afterwards, United 93 takes us on a purely visceral and emotional journey back to that very morning. Writer/director Greengrass fills in some blanks with his own educated guesses - he presumes the plane was headed towards the Capitol Building in Washington, he debunks the niggling theory that military fighter jets actually destroyed the plane in midair - he maintains a tight, tense, basically objective approach to the events.
Although the story's already been used as fodder for two TV movies, what sets this film apart is Greengrass' decision to include lengthy scenes with the FAA and the military as they react to the hair-raising drama (the great irony being that none of the personnel was even aware that United flight 93 had been hijacked until it crashed into Pennsylvania farmland). With many of the real-life military and government characters playing themselves, and the rest of the cast a collection of ordinary-looking unknowns, the film gains an extra layer of authenticity that makes for a frightening, this-could-happen-to-you experience.
I think the very point of the film is to show that the rebellious passengers on flight 93 weren't larger-than-life heroes but ordinary people who, left with no choices, launched a brave if desperate attack upon their hijackers in order to keep the plane from crashing. (One of the passengers was a small craft pilot; the apparent idea was to get him into the cockpit in order to land it safely.)
Greengrass even shows his hijackers not as mustache-twirling arch-villains but as nervous, idealistic young men - in fact, it is the noticeable youth of these terrorists (or at least the actors playing them) that struck me most. You do grow to hate them, and there is a sense of gut relief when you see the passengers rise up against them, but you can't blame Greengrass if he wants to deliver a little emotional satisfaction right before the inevitable moment of doom.
Still and all, there remains nothing sentimental or politically-motivated about this film. This isn't about "Why We Fight". There is no propaganda here. Greengrass' goal is just to put you there in the moment, which he does, and that makes United 93 a unique and gut-wrenching film. (Indeed, it's so intense that it may inspire certain audience members to avoid flying for the rest of their lives.) It's not fun, and I don't want to see it again, but it helped put me back in touch with a distinctly human drama that has become all too politicized in the years since it unfolded.