This provides sufficient airspace for the safe control and  separation of aircraft during IFR operations. Chapter 3 of  the Aeronautical Information Manual (AIM) explains the  various types of Class E airspace.  Sectional and other charts depict all locations of Class E  airspace with bases below 14,500 feet MSL. In areas where  charts do not depict a class E base, class E begins at 14,500  feet MSL.  In most areas, the Class E airspace base is 1,200 feet AGL. In  many other areas, the Class E airspace base is either the surface  or 700 feet AGL. Some Class E airspace begins at an MSL  altitude depicted on the charts, instead of an AGL altitude.  Class E airspace typically extends up to, but not including,  18,000 feet MSL (the lower limit of Class A airspace). All  airspace above FL 600 is Class E airspace.  Uncontrolled airspace or Class G airspace is the portion of  the airspace that has not been designated as Class A, B, C,  D, or E. It is therefore designated uncontrolled airspace.  Class G airspace extends from the surface to the base of the  overlying Class E airspace. Although ATC has no authority  or responsibility to control air traffic, pilots should remember  there are visual flight rules (VFR) minimums that apply to  Class G airspace.  Special use airspace or special area of operation (SAO)  is the 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.  Certain special use airspace areas can create limitations on  the mixed use of airspace. The special use airspace depicted  on instrument charts includes the area name or number,  effective altitude, time and weather conditions of operation,  the controlling agency, and the chart panel location. On  National Aeronautical Charting Group (NACG) en route  charts, this information is available on one of the end panels.  Special use airspace usually consists of:  Prohibited areas contain airspace of defined dimensions  within which the flight of aircraft is prohibited. Such areas  are established for security or other reasons associated with  the national welfare. These areas are published in the Federal  Register and are depicted on aeronautical charts. The area is  charted as a “P” followed by a number (e.g., P-40). Examples  of prohibited areas include Camp David and the National  Mall in Washington, D.C., where the White House and the  Congressional buildings are located.  [Figure 15-2]  Restricted areas are areas where operations are hazardous to  nonparticipating aircraft and contain airspace within which  the flight of aircraft, while not wholly prohibited, is subject  to restrictions. 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. Restricted areas denote the existence of unusual, often  invisible, hazards to aircraft (e.g., artillery firing, aerial  gunnery, or guided missiles). IFR flights may be authorized  to transit the airspace and are routed accordingly. Penetration  of restricted areas without authorization from the using  or controlling agency may be extremely hazardous to the  aircraft and its occupants. ATC facilities apply the following  procedures when aircraft are operating on an IFR clearance  (including those cleared by ATC to maintain VFR on top) via  a route that lies within joint-use restricted airspace:  •  Prohibited areas  •  Restricted areas  •  Warning areas  •  Military operation areas (MOAs)  •  Alert areas  •  Controlled firing areas (CFAs)  1. If the restricted area is not active and has been released  to the Federal Aviation Administration (FAA), the  ATC facility allows the aircraft to operate in the  restricted airspace without issuing specific clearance  for it to do so.  2. If the restricted area is active and has not been released  to the FAA, the ATC facility issues a clearance that  ensures the aircraft avoids the restricted airspace.  Figure 15-2.  An example of a prohibited area, P-40 around Camp  David.  15-3  Prohibited Areas  Restricted Areas  Uncontrolled Airspace  Class G Airspace  Special Use Airspace 