Restricted airspace is airspace which aircraft are prohibited from entering without advance permission. Unauthorized entries into the restricted space in Washington, D.C. are common. NORAD officials said there are typically two or three incursions a day, usually by pilots not familiar with the restrictions or who stray from their intended flight paths.
After the terrorist attacks of September 11, 2001, the government severely restricted air traffic in the region. It established an Air Defense Identification Zone -- an area consisting of a 30-mile diameter circle around Reagan Washington National Airport and 22-mile circles around Dulles and Baltimore-Washington international airports.
Restrictions are more severe in a 15.75-mile inner circle called the Flight Restricted Zone.two or three incursions a day, usually by pilots unaware of the restrictons or who stray from their intended flight paths.
"The most notable incident occurred during President Reagan's funeral activities last summer when a jet carrying Kentucky Gov. Ernie Fletcher entered the airspace with a broken transponder, prompting the evacuation of the U.S. Capitol."