In fact-based films, how much fiction is OK?

NEW YORK — The scene: Tehran’s Mehrabad airport, January 1980. Six U.S. diplomats, pretending to be a film crew, are about to fly to freedom with their CIA escort. Suddenly there’s a moment of panic in what had been a smooth trip through the airport.

The plane has mechanical difficulties and will be delayed. Will the Americans be discovered, arrested, even killed? CIA officer Tony Mendez, part of the fake crew, tries to calm them. Luckily, the flight leaves about an hour later.

If you saw the film “Argo,” no, you didn’t miss this development, which is recounted in Mendez’s book about the real-life operation.

That’s because director Ben Affleck and screenwriter Chris Terrio replaced it with an even more dramatic scenario, involving canceled flight reservations, suspicious Iranian officials who call the Hollywood office of the fake film crew (a call answered just in time), and finally a heart-pounding chase on the tarmac just as the plane’s wheels lift off, seconds away from catastrophe.

Crackling filmmaking — except that it never happened. Affleck and Terrio, whose film is an Oscar frontrunner, never claimed their film was a documentary, of course.

But still, they’ve caught some flak for the liberties they took in the name of entertainment.

And they aren’t alone — two other high-profile best-picture nominees this year, Kathryn Bigelow’s “Zero Dark Thirty” and Steven Spielberg’s “Lincoln,” have also been criticized for different sorts of factual issues.

Filmmakers have been making movies based on real events forever, and similar charges have been made.

But because three fact-based films are in Oscar contention, the issue has come to the forefront of this year’s race, and with it a thorny cultural question: Does the audience deserve the truth, the whole truth and nothing but? Surely not, but just how much fiction is OK?

The latest episode involved “Lincoln,” and the revelation that Spielberg and his screenwriter, Tony Kushner, took liberties depicting the 1865 vote on the 13th amendment outlawing slavery.

In response to a complaint by a Connecticut congressman, Kushner acknowledged that he had changed the details, having two Connecticut congressmen vote against the amendment when, in fact, all four voted for it.

In a statement, Kushner said he had “adhered to time-honored and completely legitimate standards for the creation of historical drama, which is what ‘Lincoln’ is. I hope nobody is shocked to learn that I also made up dialogue and imagined encounters and invented characters.”

His answer wasn’t satisfying to everyone.

New York Times columnist Maureen Dowd called on Spielberg this weekend to adjust the DVD version before it’s released, lest the film leave “students everywhere thinking the Nutmeg State is nutty.”