From Paul Nicholson on Flickr.

On Monday morning Southwest Airlines announced its intent to acquire AirTran Airways. The deal won’t be approved for some time, but when it is, the new combined company will likely impact air travel in Greater Washington.

The big question is when Washingtonians will finally be able to catch a Southwest flight out of National Airport, and whether a Southwest presence will bring down historically high fares at DCA.

Southwest’s biggest presence in the region is at Baltimore-Washington International, where the airline currently occupies 20 gates with 43 non-stop routes and 172 daily departures. Measured by number of departures, BWI is the 4th busiest in the Southwest system.

On the other side of town, since 2006 Southwest has operated what the company refers to as a “boutique operation” out of Dulles International. Today they occupy 2 gates with 2 non-stop routes and 8 daily departures.

What might Southwest service out of National look like?

AirTran currently has 2 gates in Terminal A with 4 non-stop routes and about a dozen daily departures. Even if Southwest maintained that level of service, it would only be a fraction of the business they do out of BWI. Southwest would likely select a few strategic city-pairs for service out of DCA, so many Washingtonians hoping for an inexpensive one-seat flight home to wherever they’re from will probably be out of luck.

More interesting is what might happen up in Maryland. BWI is both a top market for Southwest and a secondary hub for AirTran.

While the two airlines directly compete on only about a half-dozen routes, there’s legitimate fear that eliminating that competition could push fares higher. In a rare twist of events, expanded Southwest service could have the opposite effect that it historically has had. Only time will tell if Southwest’s revenue management team thinks they can successfully pull off higher fares.

At the end of the day, Southwest’s acquisition of AirTran might not have as big an impact on air travel in Washington as many are hoping. And while Southwest’s arrival at DCA will be welcome by many travelers, it will hardly be a sizable operation.