10/13/2010 11:50 am ET | Updated May 25, 2011

Midway Airport Worst In America For On-Time Departures

Midway Airport has ranked last in on-time departures in a survey of major airports -- and that might not be such a bad sign.

Two new sets of numbers gave Midway poor marks. The first, released by the U.S. Department of Transportation, showed that the airport only got 71.3 percent of its flights off the ground on time in the first eight months of 2010.

The airport's struggle in timeliness can be attributed in large part to Southwest Airlines, the carrier that does by far the most traffic at Midway. New statistics for September, released by the Portland-based Flightstats, ranked Southwest dead last in on-time arrivals. Flights coming in late to Midway are more likely to be delayed on their way out, as the airlines already runs a tight turnaround schedule.

The Chicago Sun-Times has the numbers:

The [Department of Transportation] found that 71.3 percent of Midway's flights left on time in the first eight months of 2010, compared with 77.5 percent for the same period in 2009.

Chicago's O'Hare Airport ranked slightly better. Among O'Hare departures, 75.6 percent left on time in the first eight months of 2010, DOT found.

But the struggles in on-time departures, while a nuisance for travelers, are actually a sign of growth at Midway, according to WBEZ.

The airport is a major hub for discount carriers, like Southwest and others. These airlines have been quicker to recover from the recession than the major carriers; as a result, traffic has been growing, in some cases beyond the airport's capacity.

Some problems are natural by-products of more passengers: for instance, it takes longer to deplane a full flight than an empty one. But Joe Schwieterman, a transportation expert at DePaul University, told WBEZ that Midway also has "structural problems that become more apparent with increased traffic," like short runways.

As more passengers turn to budget airlines, Midway and other airports like it may continue to struggle under the burden of greater traffic.