14.class-c-airspace. Class C Airspace
Class C airspace surrounds airports that have an operational air traffic control tower, are serviced by a radar approach control, and have a certain number of IFR operations or passenger enplanements. Class C is designed to provide ATC separation services to all participating aircraft and to sequence arriving traffic at moderately busy airports.
Dimensions
While Class C airspace is individually tailored to each airport, it generally consists of two concentric circles centered on the primary airport's reference point:
- Inner (surface) area: A 5 NM radius core that extends from the surface up to 4,000 feet above the airport elevation (charted in MSL).
- Outer (shelf) area: A 10 NM radius shelf that extends from 1,200 feet AGL up to 4,000 feet above the airport elevation.
- Outer area (procedural, not charted): A 20 NM radius procedural ring within which ATC provides traffic advisories and sequencing on a workload-permitting basis to participating aircraft. This is not regulatory airspace.
Class C airspace is depicted on VFR sectional and terminal area charts with solid magenta lines. The floor and ceiling of each segment are charted in hundreds of feet MSL (e.g., "40/SFC" for a surface area capped at 4,000 ft MSL, or "40/12" for a shelf from 1,200 ft to 4,000 ft MSL).
Operating Rules and Equipment Requirements
To operate within Class C airspace, an aircraft must be equipped with:
- A two-way radio capable of communicating with ATC.
- An operable Mode C (altitude-encoding) transponder.
- ADS-B Out when operating within and above the lateral boundaries of Class C up to 10,000 feet MSL (per 14 CFR 91.225).
There is no specific pilot certificate requirement to enter Class C airspace—any certificated pilot, including a student pilot, may operate there provided they have received appropriate training and an endorsement if required by 14 CFR 61.94 for student pilots.
Communications Requirement — "Establish Two-Way Radio Communications"
Before entering Class C airspace, the pilot must establish two-way radio communications with the ATC facility (typically the approach control) having jurisdiction over the area. The key regulatory standard is that ATC must respond using the aircraft's call sign. For example:
- Pilot: "Socal Approach, Cessna 12345, 10 miles east at 4,500, landing Long Beach."
- ATC response that permits entry: "Cessna 12345, Socal Approach, squawk 0421 and ident."
- ATC response that does not permit entry: "Aircraft calling Socal, stand by." (No call sign acknowledged—remain clear of the Class C.)
If the controller responds with the aircraft's call sign without explicitly instructing the pilot to remain clear, two-way communication has been established and the aircraft may enter the Class C. If ATC says "(call sign), remain outside Class C airspace and standby," the pilot must remain clear until cleared in.
Unlike Class B, no specific clearance (such as "cleared into the Class C") is required—communication, not clearance, is the threshold for entry.
VFR Weather Minimums
Within Class C airspace, basic VFR weather minimums per 14 CFR 91.155 are:
- Visibility: 3 statute miles.
- Cloud clearance: 500 feet below, 1,000 feet above, 2,000 feet horizontal (the "3-152" rule).
Separation and Services
ATC provides the following services to all aircraft operating within Class C airspace:
- Sequencing of all arriving aircraft to the primary airport.
- Standard IFR separation between IFR aircraft.
- Traffic advisories and conflict resolution between IFR and VFR aircraft.
- Mandatory traffic advisories and safety alerts between VFR aircraft.
Speed Limits
Under 14 CFR 91.117:
- Within Class C airspace, no person may operate at an indicated airspeed greater than 200 knots (230 mph) when at or below 2,500 feet AGL within 4 NM of the primary airport.
- Below 10,000 feet MSL, the general speed limit of 250 knots still applies.
Departures and Transitions
- Departing the primary airport: Two-way communication is established on the ground with ground/tower; sequencing and separation continue until the aircraft exits the Class C.
- Departing a satellite airport within Class C: The pilot must contact the tower (if any) or approach control as soon as practicable after departure.
- Transiting: Pilots may request a transition through Class C; ATC will provide vectors, altitudes, and traffic advisories as workload permits. If ATC is unable to accommodate the transit, the pilot must remain clear.
Practical Tips
- Listen to ATIS before initial contact and report the information code ("with information Bravo").
- Make initial contact at least 20 NM out when possible to integrate with the procedural outer area service.
- If denied entry or told to remain clear, plan a deviation route around the lateral boundaries; never enter without two-way communication established.