Set up very much like a documentary United 93 puts you right there onboard United Airlines Flight 93 the fourth hijacked plane on Sept. 11 2001 which crashed in a Pennsylvania field just short of its intended target. The first half of the film cuts between the mundane routine of boarding the ill-fated flight to the horrifying events unfolding at the World Trade Center played out in airport control towers as well as the FAA's command center in Herndon Va. and the military's center at the Northeast Air Defense Sector in upstate New York. Everyone is scrambling trying to figure out what’s happening while an air of absolute powerlessness hovers over them. Then for the last unbelievably heart-wrenching 30 minutes or so we are back on the plane. We watch as the hijackers wait and wait to make a move and then once they do watch as the passengers realize the gravity of the situation after talking with their loved ones on the ground. The heroism the defiance is palpable. "They were the first people to inhabit the post-9/11 world " Greengrass says in the press notes. And to keep things as accurate as possible Greengrass reportedly interviewed more than 100 family members and friends of those who perished in order to get not only their blessings but an inkling of what might have transpired on the plane. He also gathered facts from the 9/11 Commission Report. He hired flight attendants and commercial airline pilots to play those roles; hired several civilian and military controllers on duty on Sept. 11 including the FAA's Ben Sliney who plays himself; and finally rehearsed and shot his actors in an old Boeing 757 at England's Pinewood Studios. You’ll recognize some faces character actors who’ve been in countless films and TV shows. But the key is to keep United 93 rooted in reality--and to do that you can’t have an A-list star mussing it up. Greengrass is not afraid of making hard-hitting films such as 2002's Bloody Sunday a dramatization of the Irish civil rights protest march and subsequent massacre by British troops on January 30 1972. With United 93 he has once again documented one of modern history’s most defining moments. Of course the controversy surrounding United 93--whether or not it should have even been made--is all understandable and justifiable. Sept. 11 is still indeed a raw nerve. How can it not be? We are living in a completely changed world because of it and no amount of time can ever really alter that. But you can't fault Greengrass for feeling compelled to tell this story and can only appreciate him for doing his homework thoroughly and giving it to us straight from the heart. Sort of a collective heart I should say since it really speaks to humanity and the ways we are capable of such great courage in the face of such insurmountable odds. Obviously we will never know exactly what happened on the flight but at least we know something monumental took place. Now let’s see how Oliver Stone and Nicolas Cage handle 9/11 in the upcoming World Trade Center.