National Airspace System


  • The National Airspace System (NAS) is the network of United States airspace, air navigation facilities, services, airports, regulations, procedures, technical information, human resources, and material shared jointly between the Federal Aviation Administration (FAA) and the military
  • Divided into categories and further classified by its complexity, density, nature of operations, level of safety required, and national and public interest
  • Airspace is charted and include hours of operation, altitudes, and the controlling agency (except CFAs)

Categories of Airspace:

  • Airspace Summary
    Airspace Summary
  • There are two categories of airspace:
    • Regulatory Airspace
    • Non-Regulatory Airspace
    • Regulatory Airspace:

      • Regulatory airspace is subject to the rule-making process in order to define strict standards
      • Regulatory airspace includes Class A, B, C, D and E airspace areas, restricted and prohibited areas
    • Non-Regulatory Airspace:

      • Non-regulatory airspace is a way to classify airspace and an associated purpose, without subjecting it to the rule-making process
        • These standards in one way or another tie back to improving safety while maximizing the efficiency of operations
      • Non-regulatory includes military operations areas (MOA), warning areas, alert areas, controlled firing areas (CFA), and national security areas (NSA)

Types of Airspace:

  • There are four types of airspace:
    • Controlled Airspace
    • Uncontrolled Airspace
    • Special Use Airspace
    • Other Airspace
    • Controlled Airspace:

      • Controlled airspace is a generic term that covers the different classification of airspace and defined dimensions within which air traffic control service is provided to Instrument Flight Rules (IFR) flights and to Visual Flight Rules (VFR) flights in accordance with the airspace classification
      • Uncontrolled 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
      • Special Use Airspace:

        • Special Use Airspace (SUA) consists of airspace of defined dimensions identified by an area on the surface of the earth wherein activities must be confined because of their nature, or wherein limitations are imposed upon aircraft operations that are not a part of those activities, or both
        • Prohibited and restricted areas are regulatory special use airspace and are established in 14 CFR Part 73 through the rulemaking process
        • Warning areas, MOAs, alert areas, CFAs, and national security areas (NSA) are non-regulatory special use airspace
        • Special use airspace descriptions (except CFAs) are contained in FAA Order JO 7400.8, Special Use Airspace
        • Permanent SUA (except CFAs) is charted on Sectional Aeronautical, VFR Terminal Area, and applicable En Route charts, and include the hours of operation, altitudes, and the controlling agency
          • For temporary restricted areas and temporary MOAs, pilots should review the Domestic Notices found on the Federal NOTAM System (FNS) NOTAM Search website under External Links or the Air Traffic Plans and Publications website, the FAA SUA website, and/or contact the appropriate overlying ATC facility to determine the effect of non-depicted SUA areas along their routes of flight
        • The period of time during which a designation of special use airspace is in effect is stated in the designation
        • The horizontal limits of special use airspace are measured by boundaries described by geographic coordinates or other appropriate references that clearly define their perimeter
        • The vertical limits of special use airspace are measured by designated altitude floors and ceilings expressed as above mean sea level
          • Note that unless otherwise specified, the word "to" (an altitude or flight level) means "to and including" (that altitude or flight level)
        • When operating within SUA, Air Traffic Control (ATC) assigned airspace (ATCAA), or altitude reservations (ALTRV), flights shall be conducted under the prescribed operational area procedures appropriate to the airspace area and operation
        • SUA is technically separate and should not be confused with other airspace
        • Certain special use airspace areas can create limitations on the mixed use of airspace
        • When in conjunction with military operations you may hear the term MARSA, or Military Assumes Responsibility for Separation of Aircraft
        • Special use airspace descriptions (except CFAs) are contained in FAA Order JO 7400.8, Special Use Airspace
        • On National Aeronautical Navigation Products (AeroNav Products) en route charts, this information is available on one of the end panels
        • A list of current special use airspaces can be found on the FAA's Special Use Airspace Query page

        • VFR Corridor and Border Crossing Routes
          VFR Corridor and Border Crossing Routes, San Diego
        • VFR Corridor and Border Crossing Routes
          VFR Corridor and Border Crossing Routes, San Diego
        • Special use airspace is further divided into:
        • Regulatory Special Use Airspace:

        • Non-Regulatory Special use Airspace:

      • Other Airspace:

    • Sectional Airspace Summary
      Airspace Summary
    • Sectional Airspace Legend
      Airspace Legend

Airspace Rules, Regulations & Procedures:

Airspace Charting:

  • Airspace is charted and include hours of operation, altitudes, and the controlling agency (except CFAs)
    • Airspace hours of operation can be found in many places, such as sectional charts and Chart Supplement U.S.

Other Non-Charted Airspace Areas:

  • Stationary or Moving Altitude Reservation (ALTRV). A Stationary or Moving ALTRV is announced via an airspace NOTAM issued by the Central Altitude Reservation Facility (CARF) or ARTCC. These announcements will appear in CARF and/or ARTCC NOTAMS. This airspace ensures non-participating IFR aircraft remain separated from special activity. Non-participating VFR aircraft are permitted to fly through the area but should exercise vigilance
  • ATC ASSIGNED AIRSPACE. Airspace of defined vertical/lateral limits, assigned by ATC, for the purpose of providing air traffic segregation between the specified activities being conducted within the assigned airspace and other IFR air traffic. ATCAA locations and scheduled activation information can be found on the FAA SUA website; a NOTAM will not be issued to announce the activation of this airspace


  • The national airspace system's present configuration is a reflection of the technological advances concerning the speed and altitude capability of jet aircraft, as well as the complexity of microchip and satellite-based navigation equipment
  • It is of the utmost importance that aircraft operating independently or under the control of a ground, ship, or airborne controller remain within the specified vertical and horizontal limits of assigned airspace. Remaining within assigned airspace can only be achieved by maintaining a total awareness of details depicted in current charts, publications, and military directives, coupled with a continual assessment of the accuracy of the controlling agency's radar. It may be required to operate with self-imposed vertical and horizontal buffers to remain within assigned airspace. When operating in designated SUA, aircrews should be aware that civilian aircraft may not honor the existence of such areas, nor monitor radio frequencies to receive appropriate warning/ advisories
  • Chapter 3 of the Aeronautical Information Manual, and part 71 of the Code of Federal Regulations (CFRs) provide dimensions, exceptions, geographical areas covered, exclusions, specific transponder or equipment requirements, and flight operation information
  • It is important that pilots be familiar with the operational requirements for each of the various types or classes of airspace
  • When overlapping airspace designations apply to the same airspace, the operating rules associated with the more restrictive airspace designation apply
    • Refer to Title 14 of the U.S. Code of Federal Regulations (CFR) for specific dimensions, exceptions, geographical areas covered, exclusions, specific transponder/ADS-B or other equipment requirements, and flight operations
      • Regulatory airspace is established and governed through 14 CFR Part 73 through the rule making process
  • Not common place, there are other airspace designations such as waivered airspace that pilots may hear about, but are impractical knowledge to everyday flight operations
  • See also: Washington D.C. Special Flight Rules Area (SFRA)
  • Sectional Military Operating Area Airspace Hours
    Military Operating Area Airspace Hours
  • To conform to international aviation standards, the United States adopted the primary elements of the classification system developed by the International Civil Aviation Organization (ICAO)
  • To learn more about international flying, be sure to read the FAA's Entering, Exiting and Flying in United States Airspace guidance
  • Various air traffic control services are provided within controlled airspace, including:
  • Resources, such as AOPA's Know Before You Go: Navigating Today's Airspace, is available to help learn about the national airspace system and how to best navigate through it
  • Still looking for something? Continue searching: