Class Charlie (also referred to as "Class C") Airspace areas are designed to improve aviation safety by reducing the risk of midair collisions in the terminal area and enhance the management of air traffic operations therein
VFR aircraft can expect these services on a workload permitting basis
This can be terminated by the controller if workload dictates
Approach Control Service for VFR Arriving Aircraft
Numerous approach control facilities have established programs for arriving VFR aircraft to contact approach control for landing information. This information includes: wind, runway, and altimeter setting at the airport of intended landing. This information may be omitted if contained in the Automatic Terminal Information Service (ATIS) broadcast and the pilot states the appropriate ATIS code
Pilot use of "have numbers" does not indicate receipt of the ATIS broadcast. In addition, the controller will provide traffic advisories on a workload permitting basis
Such information will be furnished upon initial contact with concerned approach control facility. The pilot will be requested to change to the tower frequency at a predetermined time or point, to receive further landing information
Where available, use of this procedure will not hinder the operation of VFR flights by requiring excessive spacing between aircraft or devious routing
Compliance with this procedure is not mandatory but pilot participation is encouraged
Approach control services for VFR aircraft are normally dependent on ATC radar. These services are not available during periods of a radar outage. Approach control services for VFR aircraft are limited when CENRAP is in use
Class Charlie Airspace Dimensions:
Class C airspace area locations must include a single primary airport around which the Class C airspace is designated
However due to its size, it may encompass other airports which are then referred to as secondary airports
Horizontal Limits:
Class C airspace areas are generally designed as two circles centered around the primary airport [Figure 1]
Inner core: 5 Nautical Mile (NM) radius
Shelf area: 10 NM radius
Horizontal boundaries of class C airspace are delineated with a solid magenta line
Vertical Limits:
The ceiling of a Class C airspace should be 4,000 feet AGL above the primary airport's field elevation
Inner core: Surface to 4000' Above Ground Level (AGL)
Shelf area: 1,200' AGL (no lower) to 4,000'
Vertical boundaries of class C airspace are delineated with magenta numbers or letters [Figure 2]
The altitude above the magenta line is the ceiling while the altitude below is the floor
Altitude dimensions are based on AGL but charted in Mean Sea Level (MSL)
In congested areas, Class Charlie airspace may bound against others such as Class Bravo airspace
When this is the case, airspace designations will denote where the transition altitude is by designating a surface altitude and a "T" which denotes the ceiling is up to, but not including the floor of Class Bravo airspace [Figure 3]
Orlando Executive Airport (Class B), for example, bumps against Orland Stanford Airport (Class C) which requires reference of the Class Bravo airspace to determine the ceiling of Class Charlie [Figure 4]
Though not requiring regulatory action, an outer area is the procedural companion to Class C airspace
Normally this area is 20 NM from the primary Class C airspace airport
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
This outer area is NOT depicted and imposes no limitation on pilots
Pilot participation is voluntary within the outer area and can be discontinued, within the outer area, at the pilot's request
Class C services will be provided in the outer area unless the pilot requests termination of the service
Other locations may not have standard rings or standard altitudes which require attention to actual airspace dimensions, both vertical and lateral [Figure 5]
Class Charlie Airspace Depiction:
Amazon, Sectional Charts
Amazon, Sectional Charts
Class Charlie airspace is depicted on the following charts:
This means that as long as an aircraft meets the equipment requirements below, anyone from a student on up can operate within Class Charlie Airspace
Equipment:
Transponder:
Unless otherwise authorized by ATC, when operating within or above Class Charlie airspace, a transponder in compliance with 91.215 and operable ADS-B Out equipment is required
After January 1, 2020, the applicable Automatic Dependent Surveillance-Broadcast Out equipment specified in 91.225
When below Class Charlie airspace, a transponder is not required as it is for Class Bravo
Radios:
Radios are required in order to maintain two-way radio communications with the controlling agency (described below)
Aircraft Separation:
Separation is provided within the Class C airspace and the outer area after two-way radio communications and radar contact are established
IFR aircraft are separated from VFR aircraft at all times
VFR aircraft are separated from IFR aircraft within the Class C airspace by any of the following:
Visual separation
500' vertical separation
Target resolution
Wake turbulence separation will be provided to all aircraft operating:
Behind and less than 1,000 feet below super or heavy aircraft,
To small aircraft operating behind and less than 500 feet below B757 aircraft, and
To small aircraft following a large aircraft on final approach
Separation and sequencing of VFR aircraft will be suspended in the event of a radar outage as this service is dependent on radar
The pilot will be advised that the service is not available and issued wind, runway information and the time or place to contact the tower
Separation of VFR aircraft will be suspended during CENRAP operations
Traffic advisories and sequencing to the primary airport will be provided on a workload permitting basis
The pilot will be advised when CENRAP is in use
Some facilities provide Class C services only during published hours
At other times, terminal IFR radar service will be provided
It is important to note that the communications and transponder/ADS-B requirements are dependent of the class of airspace established outside of the published hours
Arrival:
Two-way radio communication must be established with Air Traffic Control prior to entry and thereafter maintain those communications while in Class C airspace
Pilots of arriving aircraft should contact the Class C airspace ATC facility on the publicized frequency and give their position, altitude, radar beacon code, destination, and request Class C service
This is a lot of information to contact a controller with, and they may not be ready
Consider the use of a "cold call" first:
Pilot: "[Agency], [Callsign], Request"
Once the controller responds, give them the full call
Radio contact should be initiated far enough from the Class C airspace boundary to preclude entering Class C airspace before two-way radio communications are established
Permission is recognized by hearing your call sign:
ATC: "Aircraft calling, standby"
It is important to understand that if the controller responds to the initial radio call without using the aircraft identification, radio communications have not been established and the pilot may not enter the Class C airspace
If workload or traffic conditions prevent immediate provision of Class C services, the controller will inform the pilot to remain outside the Class C airspace until conditions permit the services to be provided
Departure:
A primary or satellite airport with an operating control tower:
Two-way radio communications must be established and maintained with the control tower, and thereafter as instructed by ATC while operating in Class C airspace
A satellite airport without an operating control tower:
Two-way radio communications must be established as soon as practicable after departing with the ATC facility having jurisdiction over the Class C airspace
VFR Visibility Requirements:
If the pilot is operating under VFR then they must have at least 3 SM visibility, and be able to maintain 500' below, 1,000' above, 2,000' horizontal of any clouds
Speed Restrictions:
200 knots (230 mph) within 4 NM and 2,500' of the primary airport of a Class C airspace area, unless otherwise authorized
Sometimes multiple airports may fall within the airspace dimensions described above:
The primary airport is the airport for which the Class C airspace area is designated
A satellite airport is any other airport within the Class C airspace area
Small Unmanned Aircraft Operations:
No person may operate a small unmanned aircraft in Class C unless that person has prior authorization from Air Traffic Control (ATC)
No person may operate a small unmanned aircraft in a manner that interferes with operations and traffic patterns at any airport, heliport, or seaplane base
Secondary/Satellite Airports:
In some locations Class C airspace may overlie the Class D surface area of a secondary airport
In order to allow that control tower to provide service to aircraft, portions of the overlapping Class C airspace may be procedurally excluded when the secondary airport tower is in operation
Aircraft operating in these procedurally excluded areas will only be provided airport traffic control services when in communication with the secondary airport tower
Aircraft proceeding inbound to a satellite airport will be terminated at a sufficient distance to allow time to change to the appropriate tower or advisory frequency
Class C services to these aircraft will be discontinued when the aircraft is instructed to contact the tower or change to advisory frequency
Aircraft departing secondary controlled airports will not receive Class C services until they have been radar identified and two-way communications have been established with the Class C airspace facility
This program is not to be interpreted as relieving pilots of their responsibilities to see and avoid other traffic operating in basic VFR weather conditions, to adjust their operations and flight path as necessary to preclude serious wake encounters, to maintain appropriate terrain and obstruction clearance or to remain in weather conditions equal to or better than the minimums required by 14 CFR Section 91.155
Approach control should be advised and a revised clearance or instruction obtained when compliance with an assigned route, heading and/or altitude is likely to compromise pilot responsibility with respect to terrain and obstruction clearance, vortex exposure, and weather minimums
Conclusion:
Standardization is key and so variations in airspace design are only applied when absolutely required based on local requirements
Class Charlie airspace is not always operated full time
Pilots approaching an airport with Class C service should be aware that if they descend below the base altitude of the 5 to 10 mile shelf during an instrument or visual approach, they may encounter non-transponder/non-ADS-B, VFR aircraft
Unless otherwise authorized by ATC, each aircraft operation in Class C airspace must be conducted in compliance with FAR 91.129 and 91.130
An operator may deviate from any provision of this section under the provisions of an ATC authorization issued by the ATC facility having jurisdiction over the airspace concerned
ATC may authorize a deviation on a continuing basis or for an individual flight, as appropriate
Table 3-2-1 of the AIM provides a list of Class C airspace by State
