Disaster films used to be fun. “The Towering Inferno,” “The Poseidon Adventure,” and “Airport 75” were an opportunity for audiences to watch talented, aging actors slum it in a story where the melodrama and special effects were beneath them. The successful “Airplane!” franchise only speaks to their impact as disposable entertainment: a genre is ready for parody when it does not take itself too seriously, and I doubt the Zucker or Wayans brothers would dare make a spoof of “Deepwater Horizon” and its ilk. Granted, there are still some fun disaster films out there. Last year’s “San Andreas” is a white-knuckle special effects picture, and with films like “2012,” Roland Emmerich defined his career with destruction and mayhem. But in terms of critical and commercial success, the important disaster films are solemn events. They are about real tragedies.

Unsurprisingly, the shift toward somber disaster films happened after the 9/11 attacks. Prior to then, disaster movies were about events that were bigger than humanity. An indicative example is Wolfgang Petersen’s “The Perfect Storm.” George Clooney and Mark Wahlberg play commercial fisherman who face an unfathomably deadly Nor'easter, and do not survive. It’s to the credit of Petersen and his cast that the fishermen are almost ancillary, like a data point for the awesome, humiliating power of nature. It sounds silly, but the point of older disaster films is the disaster itself, not the characters who succumb to it. No one went to “The Poseidon Adventure” just so they could see Shelley Winters or Ernest Borgnine. The special effects were the real attraction, so actors and audiences collectively knew the point was to have fun.

The first modern disaster film is Paul Greengrass’ “United 93.” In cinematic terms, he took a quasi-documentary style that made “Bloody Sunday” such a success, and applied it to America’s darkest day. “United 93” looks and feels like a documentary: there are no big-name actors in it—in fact, some non-actors play themselves—and Greengrass’ handheld style give the impression that we’re in the plane alongside all those doomed passengers. Greengrass’ ambitions are noble: he strips the attack of its political implications until human cost is all that’s left. The 9/11 attacks changed the world, he argues, but the passengers had no way of knowing that. They do not define themselves as heroes, even as they work to overthrow the hijackers. Our leaders would only laud them after the fact, and the immediacy of the flight is nearly overwhelming. No one who has seen “United 93” will forgets its final few minutes.