The airspace over and surrounding the United States includes hundreds of protected areas that are restricted or prohibited from overflight or penetration by aircraft. Some of these restricted or prohibited areas are permanent, while others are temporary and change from hour to hour depending upon current circumstances. All aircraft flying in, over, or near the United States are governed by these restrictions.

North America is surrounded by an area called the Contiguous Air Defense Identification Zone (ADIZ), which is jointly administered by the United States and Canada. This area, which is almost exclusively over water, serves as a continental defense boundary. Operationally, an ADIZ is an area in which an airplane must be in communication with air traffic authorities for identification and control. Any aircraft that wishes to fly within or through an ADIZ must notify the Federal Aviation Administration in advance by filing an appropriate flight plan. Any aircraft flying in an ADIZ without authorization may be identified and treated as a threat.

In addition to the ADIZ that surrounds the United States. there is a special temporary ADIZ surrounding the Washington, D.C., area.

Flight Restrictions & No Fly Zones

When intelligence indicates a heightened security threat, Federal Aviation Administration and Homeland Security officials impose airspace restrictions at various locations throughout the United States. Flight restrictions and no fly zones are used to restrict or prohibit the types of flight operations that can be conducted within their boundaries. Most are defined by specifying a reference point on the ground, and a date and timeframe, such as August 29 from 6 AM to 6 PM. Some of these are only temporary, and are therefore known as Temporary Flight Restrictions or TFRs.