Special use airspace. Special use airspace (SUA) is a type of special airspaces in the United States designated for operations of a nature such that limitations may be imposed on aircraft not participating in those operations.  Often these operations are of a military nature.  The designation of SUAs identifies for other users the areas where such activity occurs, provides for segregation of that activity from other users, and allows charting to keep airspace users informed of potential hazards. 

Most SUAs are depicted on aeronautical charts and listed on FAA websites. Overlying Air traffic controllers can also provide SUA information.

Types 
The Aeronautical Information Manual includes the following SUAs:

Other airspace areas

A few airspaces that are considered neither special use airspaces nor the typical controlled / uncontrolled airspaces include:

 Military Training Routes (MTR)
 For military aircraft's training on “low level” combat tactics. The routes are further divided into  Military Training Routes (IR) and  Military Training Routes (VR).

 Temporary Flight Restrictions (TFR)
 To protect persons and property in the air or on the surface from an existing or imminent hazard associated with an incident on the surface when the presence of low flying aircraft would magnify, alter, spread, or compound that hazard. These include public figure visits, disaster relieves, sports events, and space-launch missions.

 Parachute Jump Aircraft Operations

 Published VFR Routes
 Help pilots transition around, under and through complex airspaces. These routes include “ Flyway”, “ Corridor”, and “Class B Airspace  Transition Route”.
 VFR Flyway: a general flight path in planning flights inside or near complex terminal airspace to avoid Class B airspace. ATC clearances are not required.
 VFR corridor: defined corridor through class B airspace. ATC communications or clearances are not required.
 Class B Airspace VFR Transition Routes: a specific flight course for transiting a specific class B airspace. These routes include specific ATC‐assigned altitudes, and pilots must obtain an ATC clearance before entering Class B airspace on the route.

 Terminal Radar Service Area (TRSA)
 Not controlled airspace from a regulatory standpoint, but air traffic control radar services are available nonetheless.

 Special Flight Rules Area (SFRA)
 Certain designated airspaces with special air traffic rules for aircraft operating, as regulated by 14 CFR Part 93.

 Weather Reconnaissance Area (WRA)
 Established to support weather reconnaissance/research flights. ATC services are not provided within these areas. Only participating weather reconnaissance/research aircraft from the 53rd Weather Reconnaissance Squadron and National Oceanic and Atmospheric Administration Aircraft Operations Center are permitted to operate within a Weather Reconnaissance Area.

 Air Defense Identification Zone (ADIZ)
 An area of airspace over land or water, in which the ready identification, location, and control of all aircraft (except Department of Defense and law enforcement aircraft) is required in the interest of national security.

 Altitude Reservation (ALTRV)
 This airspace ensures non-participating  aircraft remain separated from special activity. Non-participating  aircraft are permitted to fly through the area with caution.

 Air Traffic Control Assigned Airspaces (ATCAA)
 Airspaces assigned by air traffic controllers for the purpose of providing air traffic segregation between the specified activities being conducted within the assigned airspace and other  air traffic.

 Noise-sensitive areas
 An area is “noise-sensitive” if noise interferes with normal activities associated with the area’s use, such as National Parks, National Wildlife Refuges, Waterfowl Production Areas, and Wilderness Areas. FAA requests aircraft entering noise-sensitive areas to avoid overflying at low altitudes, specifically noise-producing aircraft (fixed-wing, rotary-wing, and hot air balloons) to fly at an altitude of at least  above ground if weather permits.

Charts 

All permanent SUA areas, except for controlled firing areas, are depicted on aeronautical charts, including sectional aeronautical charts, VFR terminal area charts, and applicable en-route charts, accompanied with these areas' respective the hours of operation, altitudes, and the controlling agency. Controlled firing areas, temporary military operations areas, and temporary restricted areas are not shown on the charts.

Notices 

In addition to charts, pilots can verify the status of permanent SUAs by contacting the using or controlling agency. These contact information are included in chart margins. For temporary or permanent SUAs requiring a NOTAM for activation, an airspace NOTAM will be issued, and pilots can the SUA status via air route traffic control centers. Alaska's military operation runs Special Use Airspace Information Service to inform civilian  traffic about certain military operation areas and restricted airspaces within central Alaska.

Outside the U.S.  
SUAs are more commonly recognized by International Civil Aviation Organization as Flexible Use of Airspace (FUA), an airspace management concept where airspaces should never be designated as purely civil or military, but rather as a continuum in which all user demands are accommodated to the greatest possible extent.

Notes

References

External links  
 Special Use Airspace & Air Traffic Control Assigned Airspace, contains currently active SUAs

 
Military aviation