Section 2. Class C Airspace Planning

  1. The criteria for considering a given airport as a candidate for Class C designation is based on the volume of aircraft or number of enplaned passengers, the traffic density, and the type or nature of operations being conducted.
  2. For a site to be considered as a candidate for Class C airspace designation, it must meet the following criteria:
  1. The airport must be serviced by an operational airport traffic control tower and a radar approach control; and
  2. One of the following applies:
  1. An annual instrument operations count of 75,000 at the primary airport.
  2. An annual instrument operations count of 100,000 at the primary and secondary airports.
  3. An annual count of 250,000 enplaned passengers at the primary airport.
  1. Class C designation contributes to the efficiency and safety of operations and is necessary to correct a current situation or problem that cannot be solved without a Class C designation.


Operations counts are available from the Office of Aviation Policy and Plans, Statistics and Forecast Branch, APO-110. Enplaned passenger counts may be obtained by contacting the Office of Airport Planning and Programming, APP-1. Current validated counts are normally available in mid-October of the current year for the previous year.


Class C airspace areas should be designated around a single primary airport.


In general, airspace design identifies simplification and standardization of Class C airspace areas as prime requisites. Containment of instrument procedures within Class C airspace is not required. Lateral and vertical limits must be in accordance with the following, to the extent possible:

  1. Lateral Limits. Class C airspace areas should initially be designed as two concentric circles centered on the airport reference point. The surface area should have a 5 NM radius, and the outer limits of the airspace area should not extend beyond a 10 NM radius. Wherever possible, use VOR radials and DME arcs to define the boundaries of the airspace and any of its sub-areas. It is important, however, that prominent visual landmarks also be considered to assist the VFR traffic preferring to remain clear of Class C airspace.
  2. Vertical Limits. The ceiling of a Class C airspace should be 4,000 feet above the primary airport's field elevation. The surface area extends from the surface to the upper limit of the airspace. The floor of the airspace between the 5 and the 10 NM must extend from no lower than 1,200 feet AGL to the upper limit of the airspace.
  3. Variations. Any variation from the lateral and vertical limits design guidance must be justified in the staff study and recommended by the Service Center. (The number of sub-areas must be kept to a minimum.)


Though not requiring regulatory action, an Outer Area is the procedural companion to Class C airspace. The normal radius of an Outer Area is 20 NM from the primary Class C airspace airport. Its vertical limit extends from the lower limits of radio/radar coverage up to the ceiling of the approach control's delegated airspace, excluding the Class C airspace itself, and other airspace as appropriate.

  1. Class C airspace areas may be designated as continuous or part-time. If part-time, the effective time must be stated in local time. In order to designate a part-time Class C airspace area, the following statement must be included in the airspace description: “This Class C airspace area is effective during the specific dates and times established, in advance, by a Notice to Air Missions (NOTAM). The effective date and time will thereafter be continuously published in the (insert appropriate publication from below)."
  1. The appropriate volume of the Chart Supplement U.S.;
  2. Chart Supplement Alaska; or
  3. Chart Supplement Pacific.
  1. For permanent changes to existing part-time Class C airspace area designations, the following actions must be accomplished:
  1. Issue an airspace NOTAM specifying the new part-time Class C effective hours.
  2. Submit the new part-time Class C effective hours to AIS for publication in the appropriate Chart Supplement.
  3. Retain the NOTAM specifying the new part-time Class C effective hours until the new hours are published in the appropriate Chart Supplement.
  1. For unexpected events that affect the availability of part-time Class C services, issue a service NOTAM, in accordance with FAA Order 7930.2, Notices to Air Missions, describing the ATC service available and duration. No airspace NOTAM is issued.
  2. Notices to Air Missions specifying the dates and times of a designated part-time area may be issued by the appropriate facility only after coordination with the Service Center. The Service Center must ensure that such action is justified and in the public interest.