As predicted, a key to getting federal approval of the proposed American Airlines/US Airways merger are antitrust issues at Washington Reagan National Airport. Reuters reports on some of the resulting lobbying:

The airlines may be required to shed slots Washington’s Reagan National Airport to prevent market domination. There is concern that those slots could go to rivals, such as JetBlue Airways (JBLU.O), which would likely use them for flights to major cities.

That could have the trickledown effect of leaving smaller markets such as Tallahassee, Florida; Augusta, Georgia; and Charleston, West Virginia, without a daily flight to the nation’s capital.

A letter signed by at least 100 members of Congress is expected to be sent to the U.S. departments of Transportation and Justice next week, requesting that the merged carrier not be required to shed slots at Reagan National, according to two people familiar with the effort. The airport is used regularly by members of Congress to fly in and out of the nation’s capital.

Note that US Airways has recently starting service to the east from places like Omaha and Des Moines plus proposed service to Oklahoma City with flights to both Charlotte and Reagan National. So slot availability could in theory have an impact on growth from Charlotte as well.