Flight 93

On the morning of September 11, 2001, after a 40-minute delay, United 93 left Newark International Airport for San Francisco. It was the last of the four planes to be hijacked, and the only one not to hit its intended target.

Everybody on board died after passengers attempted to take back control of the plane, which crashed into a field in Pennsylvania. Songs, poems and books have addressed the subject, as have documentaries and a TV movie. But there has not been a film for cinema. Not until now.

United 93, directed by Paul Greengrass, is shockingly powerful. It is also painstakingly accurate. John Farmer, a former attorney-general of New Jersey and senior counsel to the 9/11 commission, says the film is “closer to the truth than every account the government put out before the 9/11 commission's investigation”.

In 2002, Brigadier General Montague Winfield had told ABC: “The decision was made to try to intercept flight 93…The president had given us permission to shoot down innocent civilian aircraft that threatened Washington DC. In the National Military Command Center, everything stopped for a second as the impact of those words (sank) in.” Yet, as the film shows, the military was not following United 93. It was not even informed that the plane had been hijacked until four minutes after the crash. And authorisation to shoot down commercial aircraft was not received until about 30 minutes later. The point to remember is that the passengers and crew aboard United Airlines Flight 93 really were alone. They were all that stood between the hijackers and Washington.

Greengrass, who directed the Hollywood blockbuster The Bourne Supremacy, is best known for making films about the flash point at which politics turns to violence, most notably 2002's Bloody Sunday, a drama about the day that changed the course of history in Northern Ireland. Like that film, United 93 avoids polemic. It is shot as if by fly-on-the-wall cameras as events unfold. It lets us inside the plane, and the military and civilian air-traffic control centres, but shows nothing beyond. It doesn't show President Bush, nor even the relatives who took those last, chilling calls from passengers.

Greengrass wanted to take viewers back to the event and see how perspectives have changed. “Film can take you there in a way the published reports can't,” he says. “Cinema creates images that endure, sequences that don't automatically mean anything in themselves, but populate your consciousness. This film is like a Rorschach test. Anybody, of any persuasion, can see things in it. But I hope it's also rigid enough to challenge any view.”

Greengrass had talked to the producers Working Title about making this film more or less since the events occurred, but only found the opportunity to start work last summer. “Normally, we would develop a script,” says co-producer Tim Bevan, “and the process would take two or three years. In this case, we had just a 21-page treatment. But we said, okay, let's make it. That day changed all our lives, and it's important to explore that.”

Greengrass got hold of a decommissioned Boeing 757 and shipped it to Pinewood to be reassembled and mounted on gimbals that could simulate a full range of movement. The interior was fitted out precisely, in the style of a 2001 United jet. Similar efforts were made to represent the air-traffic control and military scenes correctly: the screens replayed real data. Meanwhile, to flesh out his treatment, Greengrass engaged a respected American journalist, Michael Bronner, to talk to military officers, representatives of the FBI and the 9/11 commission, and civilian air-traffic controllers such as Ben Sliney, who ran the overall civilian operations on September 11 -which was also his first day in that job.

The hijack was rehearsed 14 times, in takes lasting from 20 minutes to 55. But how could actors know what really happened? “We had a timeline,” says Lorna Dallas, who played a passenger, Linda Gronlund, “a graph showing the known facts and the times of the phone calls.” Like other actors, Dallas met relatives of the person she played. The family let her hear a recording of Gronlund's last phone call. But this is not a film about individuals completing neat character arcs. Particular passengers may be recognised by their family, and one is casually mentioned by name, but most are no more familiar to viewers than they would have been to each other. There are no stars in the cast.

Actors say behaviour was determined not just by who they played, but by where they sat. Were they near the cabin crew? Who made the calls? And how was the news about the Twin Towers disseminated?

Greengrass deliberately segregated the actors playing hijackers until the end.

“There was a real build-up to the first meeting,” recalls Dallas. “When they appeared, there was a sharp intake of breath. Their eyes were cast down on the floor as they came into the green room.” Greengrass knew what he was doing: “The more you can create a frisson of real tension, the more truthful the performance.”

After the very first take, Jamie Harding (who played the hijacker Ahmed Al Nami) was sobbing. “We all came out with stuff we've never seen in ourselves before,” says Harding.

“We spent so many hours throwing our trays around and bleeding and screaming and crying and praying, throwing up and peeing ourselves and trying to imagine every possibility of what these people were going through,” says Cheyenne Jackson, who played another passenger, Mark Bingham.

“But we could wash off our make-up and come out.” Jackson's point, of course, is that the real passengers couldn't do that. But many people centrally involved in the events of the day did survive -and in United 93, they play themselves.

“I put real people into the film,” says Greengrass, “because that's a way of encoding a certain degree of accountability. You might, as a director, be able to pressure one real person to go along with your idea of how it should be presented, but you can't control lots of them. We had military people in the military control room who were actually there on the day, and real air-traffic controllers. In the plane, we had real pilots and stewardesses. That restricts a director's flights of fancy. Nobody will watch this film and say, ‘That can't happen.'”

Sliney, invited to attend the filming at Pinewood, was asked to play a small role in the New York air-traffic control centre. He stayed to watch scenes in which he himself was played by an actor. But it turned out that the actor couldn't pull it off. For the last day of shooting that scene, it was clear that Sliney was needed to play himself. He did eight takes, lasting an hour each. “In every scene,” says Greengrass, “we had a mixture of real professionals and actors. Out of that mixture, you get something very special. The real people guide the scene, and the actors are like tools to build up the intensity. You can't say to a non-actor that you need them to get up to the next level. But an actor can set the pace.”

Sliney recalls being dogged by an actor who kept asking him questions. “This guy kept saying ‘What's going on?' and ‘What has happened with the hijack?' So, eventually, I said to him, ‘Hey, give me a minute here.'”

The improvisation surprised Greengrass. “Going into the film, obviously we knew roughly what happened. We know, for example, that the plane descended suddenly, more steeply than a commercial airliner would do. But only when we got on set did we understand what that data means emotionally. Everyone was meant to believe this was a routine hijack, if there is such a thing. And nobody could have believed what was truly planned. The telephone calls were important, and the knowledge that the pilots were dead, but that lurching descent marked a huge perceptual shift for the passengers.

“People say actors are there to make things up. But actors can unlock the truth.

That is their skill, to find out what feels believable. And in that clinching moment, there was no doubt. You just knew that when that dive was over and the plane levelled out, you would say, ‘Something terrible is going to happen.'”

The actors playing the hijackers took similar care over their performance. How did they respond to the excruciating delay before takeoff? Was God not, after all, on their side?

A still deeper layer of insight may be available to viewers who understand Arabic, says Khalid Abdalla, who played the hesitant leader, Ziad Jarrah. “There are horrible ironies that a Muslim would certainly catch, like saying ‘In the name of God the merciful and compassionate' when you slit a throat.”

A Muslim audience will see that, as well as the hijack of the plane, there's a second hijacking, of the religion. At the film's premiere in New York, one of Egypt's biggest film stars told Abdalla he had done a service to Islam. “My first feeling,” says Abdalla, “when I heard about this part, was that I absolutely wasn't interested. I had the same reaction a lot of people have when they hear about the film. They don't want to see it, and I didn't want to be in it.” But he went along to meet Greengrass. “Paul's first question was, ‘Do you think it's possible to do this film right?' I was sitting with Omar , and our first response was, yes, but only if you contextualise it.”

Greengrass forcefully disagreed. “Paul's argument, which I have totally come around to,” says Abdalla, “was that there is also value in just trying to observe the moment. I didn't understand that at first, but witnessing human moments is fundamental to our ethical understanding. And that's what this film does: it plays out many of the human dramas of that day.

• United 93 opens on June 2