If this film sets the tone for the many 9/11 related films in the pipeline it will have served a useful purpose. Though necessarily conjectural in detail, in broad terms it tries to tell the nightmare story whose tragic ending we all know, without embellishment. Claustrophobic cinematography, an atmospheric understated score and self-effacing performances by a largely unknown cast, give Greengrass’s film an impressive air of authority. Its razor-sharp, relentless editing creates a crescendoing pace towards chaos that is so effective that at moments one has to remind oneself to breathe out.

No, the questions that press in remorselessly are not aesthetic. There is no sign of disrespect towards these iconic victims in the form or content of this superbly crafted docu-drama. It is in the fact of its existence and its commercial cinematic production and distribution within a disturbingly opaque political context, that one’s doubts and qualms are aroused. There are no rights and wrongs here – only judgements. Many Americans for example, regard re-cycling 100’s of tons of metal from the World Trade Centre debris into the building of a new warship, as respectful and appropriate recognition. Others, and I am among them, regard it as at best, deeply insensitive to the precious uniqueness and diversity of belief of the thousands of human beings whose lives were erased before our very eyes in September 2001. Death. Live. Reality TV with avengeance. Greengrass’s film engenders precisely the same ambivalence – you cannot look away for a moment, but feel as if you should. Seductive, transfixing imagery. Obscene in effect, but not intent.

Greengrass has made some no doubt sincere efforts to justify his film. That he made it, not how he made it. For me, the ultimate justification is that he has recreated an image of an appalling reality with such care and attention to detail that it forces us to ask ourselves – should I be watching this? And genuinely struggle with the answer. Whatever it may be. After all, unlike the live TV pictures, United 23 is a planned, financed, publicised creation, that will make a substantial, intentional and desired profit. The camera makes unwitting but not always unwilling, voyeurs of us all. All is intention. And you can’t prove an intention. I hope I will not be misunderstood when I recall a harrowing but in a sense uplifting story from the concentration camps: in unspeakable conditions, with no shred of privacy, when individuals went to the toilet, their fellow inmates, human beings, turned away. Cherishing the dignity of another and with sensitivity recognising it through refusing to look.

I would not argue with the view that watching the film of the original events of 9/11 was in a sense a duty - in a democratic society. Yet real political events and actions that led up to such insanity helped bring it about. And unless we are in a sense responsible for the actions of those we elect, then democracy is a sham. But in their endless repetition, are we in a sense watching the same images? Is the legitimacy, sensibility of these repeated viewings, automatically validated by the fact that in a literal sense they are the same? This is the kind of dilemma Greengrass’s film poses for me. Surely it is of the logic of corruption that we are unaware of it when it is taking place?

Refusing to watch the events of 9/11 as a means of denial is as dubious as passively sharing their repetition. The great strength of United 63 is that as it displays good judgement, avoiding all the major pitfalls and horrendous insensitivities we may fear from future films, it poses profound questions about our relationship to images we pay to see and that are created with the motivation to profit. Only in this can I see real justification – the film does not, and does not seek, to offer any insights or explanations to illuminate these dreadful events. To help us understand them better. To accept the view that they are simply inexplicable, meaningless, insane acts by insane people is to buy into the fear and paranoia peddled by politicians both sides of the Atlantic. There is no future or peace in victimhood. Even less if it is revengeful.

And I cannot help but wonder whether a film with the same rigorous attention to detail and concern for the horror experienced by precious human beings, about to die needlessly and pointlessly, would get made, still less watched, if it were set in Baghdad on the first night of what was called ‘Shock and Awe’ - to America’s eternal shame. And ours.