Three aircraft will fly over Washington in the wee hours of the morning on Wednesday as the North American Aerospace Defense Command (NORAD) conducts an exercise called Falcon Virgo.

The exercise will include two Cessna aircraft from the Civil Air Patrol, the civilian auxiliary of the U.S. Air Force, as well as a U.S. Coast Guard MH-65 Dolphin helicopter. Flights will take off from Reagan and Davison airports and will fly between midnight and 2 a.m.

NORAD said in a press release that this exercise will include practice of intercepting and identifying other aircraft, as well as a test of the Washington region’s Visual Warning System.

NORAD has conducted similar exercises since the attacks of September 11, 2001, and has responded to more than 5,000 possible air threats in the U.S. in that time, the agency said. The last exercises in the Washington area were in mid-July.

The flights will be postponed or canceled in the event of bad weather.