Atlanta has the worst record this year, with more than 35 percent of flights delayed; Chicago’s O’Hare ranked last in 2004 with 30 percent.

Two weeks ago, Ken Mead, the inspector general at the U.S. Department of Transportation, predicted that this summer will be the worst ever for flight delays, with more than 25 percent of planes leaving late. Get ready to spend some time parked on the tarmac at the nation’s busiest airports.

Mead cited rising demand as a cause of delays and also faulted the growth of low-cost carriers. But blaming low-cost airlines like Southwest and JetBlue for air-travel delay is exactly backward. The most important source of late flights at big airports is completely within the major airlines’ control. In fact, the evidence shows the major carriers are creating the delays on purpose.

At first glance, this seems crazy. The common explanation given for flight delays is that too many people are flying: The more air traffic, the more delays. That’s what most economists say, too. This view of airport congestion makes it seem just like highway congestion. Each time an airline schedules a flight, it doesn’t take into account the backups it causes by crowding the airspace. The dynamic generates a tragedy of the commons, in which each of the companies vying for runway slots has an incentive to overschedule.

More here.