A hundred relatives of United 93 passengers were seated together for the premier of “United 93” at Tuesday night’s opening of the Tribeca Film Festival. They were asked to stand before the film began, and within seconds the whole theater joined them with a standing ovation.

Nearly two hours later, the screen faded to a silent black and the sounds of sobbing overtook the Ziegfeld Theater. The relatives clearly had been crying for quite a while – but the actors’ screams on the big screen had drowned out the sounds of their real-life sorrow.

By definition, movie premieres are festive events. A red carpet for boldface names and free popcorn for everyone are standard fare. Directors traditionally make speeches about their inspiration. Audiences reflexively applaud in appreciation.

But as 1,100 of us clapped our hands Tuesday night, there seemed something a bit unseemly about applauding a film that will profit from America’s worst day.

Before the film began, festival leaders Robert de Niro and Jane Rosenthal reminded the audience how they created the Tribeca Film Festival six months after the September 11 attacks in an effort to bring life and lifestyle back to Lower Manhattan. Nearly five years after the attacks, though, the annual film festival seems less connected with the attacks of September 11, 2001.

Some people are concerned that “United 93” is debuting too soon after the terrorist attacks. Unfortunately, the attacks are being used to justify making the film in the first place.

“United 93” filmmaker Paul Greengrass introduced his project by thanking victims’ families for their support. He said many of them actually wanted him to make the film – a point he also makes in the trailer promoting the movie in theaters. Mr. Greengrass is using the families to insulate himself from criticism – if they like the idea of the movie, how can the rest of us object?

Universal Pictures is donating 10% of the opening weekend’s proceeds to a fund for victims’ families. Come on. Ten percent of a weekend’s take is just enough to sound generous but not really be truly generous at all. The real Hollywood money comes from the so-called “back end” – foreign rights and DVDs. How about 10% of that? Think of it as a “referral fee” for the idea. The film isn’t as objectionable as the use of the victims’ families to make the film unobjectionable.

Movies, of course, are not all documentaries – and Mr. Greengrass goes out of his way to emphasize that “United 93” is not a factual reenactment of what happened on the board the actual flight.

There are many unanswered questions – impossible to answer questions – about the final minutes before the Boeing 757 crashed into a Pennsylvania field. But Mr. Greengrass sacrificed too much non-fiction to make in his semi-fictional film.

Thanks to an ABC News producer, Jill Rackmill, we do have some sense what the four hijackers were doing, and saying, as they took control of the jetliner. Soon after the September 11th attacks, Ms. Rackmill obtained recordings of radio transmissions between United 93 and the air traffic control center in Cleveland that was monitoring the flight.

The hijackers repeatedly pressed the wrong button in the cockpit, thinking they were speaking to passengers in the cabin but instead broadcasting to air traffic controllers. That’s how we know one hijacker, later identified as Ziad Jarrah, tried telling passengers, “We have a bomb on board.” But Mr. Greengrass leaves out this dramatic moment, as Cleveland air traffic controllers accidentally found out United 93 wasn’t just another “suspected hijacking” during a morning full of false alarms.

Mr. Greengrass candidly admits this film based on actual events is truncated for storytelling purposes. But Mr. Greengrass’s admissions don’t change perceptions. And people who see this movie are bound to draw conclusions and mistakenly assume fiction is fact. Just as significantly, the absence of facts will lead them conclusions as well. Along with invoking his right to poetic license, the least Mr. Greengrass owed us was to use the facts at his disposal.

Thousands of feet in the air, Mr. Greengrass depicts a European passenger as resisting efforts to attack the hijackers. He shows a hijacker in the bathroom methodically assembling a fake bomb. He shows the passengers fighting their way into the cockpit. We will never know if any of that actually happened, and we shouldn’t be led to believe it did.

Mr. Greengrass’s finest moments are his depictions of what we know happened on the ground. The scenes at Federal Aviation Administration headquarters in Herndon, Va., control towers in Cleveland, New York, and Boston, and a military base in Rome, N.Y. are gripping and reveal the government’s frightening inability to respond.

The Tribeca Film Festival began five years ago as part of the city’s efforts to revive Lower Manhattan in the months after the terrorist attacks. Now Tribeca is booming and the festival has morphed into the fabric of city life. And notably, the Ziegfeld is miles away.

Mr. Goldin’s column appears regularly.