United 93 is the astonishing account of the 'other' plane to be hijacked on 11th September 2001. Director Paul Greengrass talks to Sheena Sweeney about the ramifications of bringing one of the most sensitive subjects of recent history to the big screen.

As the fifth anniversary of 9/11 approaches, some high profile artists have, in the last few months, interpreted that day through their work. Jay McInerney centred his uneven book The Good Life on it. Martin Amis wrote a chilling story, The Last Days of Muhammad Attafrom the viewpoint of one of the hijackers, which was published in the April edition of The New Yorker. And Oliver Stone's blockbuster World Trade Centre starring Nicolas Cage is due out, some would say rather indelicately, in September. And then there's writer/director Paul Greengrass's brilliant version of it all, United 93. The film is ninety-one minutes long in homage to the time that the United Airlines Flight 93 was in the air on that fateful day when it left Newark Airport after a forty-five minute delay on its way to San Francisco. It begins with a group of Muslim men praying and making preparations. We follow the four men on to the UA93 flight where they wait for their opportunity as the other passengers idle away the time in happy oblivion. The first hour of the film cuts back and forth between that, and one military, one federal, and three commercial airport control centres in or around New York as the events of the morning begin to unfold. And then in the last half hour when the World Trade Centre and the Pentagon have been attacked, the hijacking of UA93 is well under way, and the air traffic control centres are in a state of chaos, the action shifts to detail, in distressing moment by moment real time, what Greengrass imagines occurred on that plane.

Paul Greengrass is best known for his 'creative work based on fact', as in Omagh, which he wrote and produced, and Bloody Sunday, which he wrote and directed. Both films offer a version of two landmark events connected with the troubles in Northern Ireland. What makes Greengrass's work stand out from other docudramas is his instinct for natural dialogue that overlaps, the 'you are there' handheld photography (for which much of the credit in the case of United 93 must go to Ken Loach's regular cinematographer Barry Ackroyd), and the superb editing that allows stories to unfold through well paced cross cutting. This all brings a level of unsettling verisimilitude to United 93. But it's not just these elements that make this film so compelling, Greengrass's commitment to the pre-production process was rigorous. The story is garnered from the air traffic control recordings and the recorded telephone calls that the passengers made to their loved ones from the plane. He also conducted seven weeks of personal interviews with the families and friends of the passengers and crew, as well as the military personnel and flight controllers who were working that day. Greengrass is a controversial director, not just for the material he chooses, but also for his approach to filmmaking. His attitude to actors, for example, is irreverent. He often uses non-actors in his films, and for United 93 the Federal Aviations Administration chief Ben Sliney, a central character, plays himself; Greengrass also cast a formerly non-acting pilot and some stewards in the film. Talking about Bloody Sunday, which he cast in the same way, Greengrass said 'an actor can play a role, but how can an actor really understand what it felt like to be a soldier unless he had some experience of the military somewhere in his life?'

There is a hint of Greengrass's thoroughness in the way he communicates. He takes his time, considers every question very carefully, and speaks slowly and at length when he is ready to answer. Given that exacting nature, his views on actors, his commitment to telling the story above everything, and his social conscience, it's quite amazing that he ever worked within the fast and fickle Hollywood system long enough to make the brilliant The Bourne Supremacy. And he's about to do it again with the last part of the trilogy, The Bourne Ultimatum. 'I've always tried to make different sorts of films; I've been lucky enough to make a range of different films, and that's something I want to keep on doing. That's one of the great virtues of making films in Hollywood, you can make different genre films, you can make big films, you can make small films, you can make entertainments and private passion films. It gives you choices.' But he has been particularly absorbed with social realism throughout his career; as well as the two Northern Irish movies he also made The Murder of Stephen Lawrence, about racism in the British police system, and worked on the popular political TV show World In Action. He says he doesn't want to sound like a 'twat' by saying that he's driven by social injustice, 'I don't want to sound pompous or self regarding – and I'm sure I suffer from that just like everybody else – but I try to be humble about these things. It's not about me, I just want to know the answer to certain questions. They're journeys for me really. It sounds selfish, but I just think that's the right way to make films.'

So what about the accusation being bandied about that it's too soon to make movies about 9/11? Or the idea that it's inappropriate to use either art or entertainment, to interpret the events of that day? 'Well I don't agree, you know. We have to speak of what occurs. This happened. This is the single event that drives all our politics today, and has done for the last five years. And we have to explore 9/11 if we're going to be able to make rational choices about where we go from here. And one of the truths that you see very clearly when you make a film about 9/11, and you study the events, is that we went to war literally in the space of two hours. And that's the situation. We went to war in the space of two hours against an enemy we never saw, didn't understand, in a state of unbelievable confusion. And when you watch that unfold in this film, I think you ask yourself the hard questions. Is that likely to have got us to the right place today? Should we not think now about where we've come from and where we're going to?'

Is this what he is talking about in the press notes accompanying the film when he said that the events that took place on board Flight United 93 were a microcosm of the post 9/11 world we faced, and the choices we had to make? 'Well yes. It's really what drew me to this story. There were four planes on that day, and this was the last, it wasn't meant to be the last it was meant to take off when the other planes took off, and if it had done it would have crashed into the Capital Building and destroyed it. But by chance, there were air traffic control delays at Newark Airport and the plane was late taking off. What that meant was that by the time the plane was hijacked at 9:30 that morning, 9/11 was basically all over. I mean the towers in New York had been struck at 9 am; the Pentagon was just about to be struck. And what it meant was that those forty men and women on board that airplane were the first people to enter our world, which was the post 9/11 world, and they were the first people to face our choices, our dilemmas. What are we going to do? Do we sit here and do nothing? Do we do something and if so, what? And above all what are going to be the consequences of what we do? And this film is an attempt to walk through those two hours of 9/11 in the air traffic control rooms on the ground, in the military command centres, and inside that airplane in an attempt to give us the experience of what those two hours, that changed all our lives forever, was like.' All good questions to which Greengrass doesn't have any answers, or at least none that he wants to share. And perhaps raising the questions is enough; the rest is up to us.

United 93 is released on June 2nd
See review here.