WASHINGTON (CBSDC/AP) — NORAD is planning a series of training flights over the Washington area this week.

The North American Aerospace Defense Command says the flights will begin Wednesday night and continue into early Thursday morning. In the event of inclement weather, the exercise will be moved to the following evening.

The exercise involves Civil Air Patrol aircraft, Air Force F-16s and a U.S. Coast Guard helicopter.

NORAD says the flights are planned to hone its intercept and identification capabilities and to test the region’s visual warning system to respond to potentially threatening aircraft.

The test flights have become commonplace in since Sept. 11, 2001. In the past 11 years, fighters have responded to more than 3,400 possible air threats in the United States.