Unless otherwise authorized, each aircraft must establish two-way radio communications with the ATC facility providing air traffic services prior to entering the airspace
The portion of the airspace that has not been designated as Class A, B, C, D, or E.
Examples of these areas include Camp David and the National Mall in Washington, D.C., where the White House and the Congressional buildings are located
Designation for airspace in which certain activities must be confined, or where limitations may be imposed on aircraft operations that are not part of those activities.
These areas are published in the Federal Register and are depicted on aeronautical charts
Restricted areas are areas where operations are hazardous to nonparticipating aircraft
All operations in this airspace is conducted under instrument flight rules (IFR).
Activities within these areas must be confined because of their nature, or limitations may be imposed upon aircraft operations that are not a part of those activities, or both.