Navigating Airports: Charlie Airspace Explained

Class C airspace is a busy category of controlled airspace found near mid-size airports that service both general aviation and airline traffic. Class Charlie or Class C airspace is used for controlled zones above and around airports and for airspace above 10,000 feet (3,050 m) up to 66,000 feet (20,100 m). The primary airport in a Class C airspace has an operational Air Traffic Control Tower (ATCT) as well as Terminal Radar Approach Controls (TRACON). Secondary smaller airports may also be located within the Class C airspace. The purpose of Class C airspace is to enhance aviation safety in the terminal area and to decrease the risk of mid-air collisions by providing traffic separation services.

Air Traffic Control (ATC)

ATC provides essential services to arriving and departing aircraft through the ATCT and TRACON, adhering to both Visual and Instrument Flight Rules (VFR/IFR). Pilots must meet specific operational requirements established by ATC to operate within Class C airspace. When other airports are within the same airspace dimensions as the primary airport, they are considered satellite airports.

ATC facilitates safe arrivals and departures by sequencing aircraft to the primary airport and providing basic radar services. They also offer Class C services within the Class C airspace and the outer area, which is typically a 20 NM radius from the primary Class C airport. VFR aircraft can generally expect these services based on workload capacity. To ensure safety, ATC separates VFR aircraft from IFR aircraft within the Class C airspace through visual separation or by assigning altitudes that do not conform to standard regulations.

To receive Class C services, pilots of arriving aircraft must establish two-way radio communication with the Class C airspace ATC facility before entering the airspace. They provide essential information, including their position, altitude, radar beacon code, destination, and request for Class C service. If workload or traffic conditions prevent immediate service provision, pilots may be instructed to remain outside the Class C airspace until conditions allow.

ATC also provides crucial information to pilots, such as wind and runway details, and advises them if the service is unavailable. Some facilities offer Class C services only during published hours, providing terminal IFR radar service at other times. It is important for pilots to note that communication and equipment requirements may vary depending on the airspace class outside of published hours.

Primary and secondary airports

Class C airspace, also known as Class Charlie airspace, is a busy category of controlled airspace found near mid-size airports that service both general aviation and airline traffic. The primary airport in a Class C airspace has an operational Air Traffic Control Tower (ATCT) and Terminal Radar Approach Controls (TRACON). Secondary smaller airports may also be located within the Class C airspace. The purpose of Class C airspace is to improve aviation safety by reducing the risk of mid-air collisions in the terminal area and enhancing the management of air traffic operations.

The typical radius of an outer area is 20 nautical miles (NM) from the primary Class C airspace airport. Its vertical limit extends from the lower radio/radar coverage limits up to the ceiling of the approach control's delegated airspace, excluding Class C and other airspace as appropriate. The ceiling of a Class C airspace should be 4,000 feet Above Ground Level (AGL) above the primary airport's field elevation. The inner core spans from the surface to 4,000' AGL. The shelf area spans from 1,200' AGL (no lower) to 4,000'. Magenta numbers or letters identify the vertical boundaries of class C airspace.

Class C airspace areas are generally designed as two circles centred around the primary airport. The inner core has a radius of 5 nautical miles (NM). The shelf area has a radius of 10 NM. Solid magenta lines identify the horizontal boundaries of class C airspace. In congested areas, Class Charlie airspace may be 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.

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. When other airports fall within the airspace dimensions as the primary airports, they are considered satellite airports. A satellite airport is any other airport within the Class C airspace area. Class C airspace may extend over a secondary airport's Class D surface area.

Inner and outer rings

Class C airspace, also known as Class Charlie airspace, is a busy category of controlled airspace found near mid-size airports that service both general aviation and airline traffic. The primary airport in a Class C airspace has both an operational Air Traffic Control Tower (ATCT) and Terminal Radar Approach Controls (TRACON).

The inner and outer rings of Class C airspace play a crucial role in maintaining safe and efficient air traffic operations. The inner ring typically extends from the surface to 4,000 feet above the airport, with a radius of 5 nautical miles (NM). It is designed to keep departing and arriving aircraft at the larger airport safely separated from other traffic. The outer ring, on the other hand, typically spans from 1,200 feet above the airport to 4,000 feet, with a radius of 10 NM. The outer ring is not depicted on charts and does not impose any limitations or mandatory requirements on pilots. Participation in the outer ring is entirely voluntary, and pilots can choose to opt-out of Class C services.

The vertical boundaries of Class C airspace are visually represented on aeronautical charts by two concentric magenta circles, denoting the inner and outer rings. Inside each circle are two bold magenta numbers, stacked on top of each other and separated by a horizontal line. The top number represents the ceiling of the airspace in hundreds of feet MSL, while the bottom number indicates the floor. For example, if the top number is "40," it means the ceiling of the airspace is 4,000 feet MSL. The altitude dimensions are based on AGL but are charted in MSL.

Class C airspace is designed to enhance aviation safety and reduce the risk of mid-air collisions near busy airports. The inner and outer rings help segregate air traffic, allowing slower and lower-flying aircraft to operate safely outside the inner ring while maintaining efficient operations for the larger airport within.

Clearance requirements

Class C or Class Charlie airspace is a busy category of controlled airspace found near mid-size airports that service both general aviation and airline traffic. The primary airport in a Class C airspace has both an operational Air Traffic Control Tower (ATCT) and Terminal Radar Approach Controls (TRACON). Secondary smaller airports may also be located within the Class C airspace.

The purpose of Class C airspace is to enhance aviation safety in the terminal area and to decrease the risk of mid-air collisions by providing traffic separation services. Both Visual Flight Rules (VFR) and Instrument Flight Rules (IFR) traffic can operate within Class C airspace provided they meet the operational requirements.

To enter Class C airspace, you must obtain a landing clearance. You must establish two-way radio communication with ATC before entering Class C airspace. You can do this by calling ATC on the radio and ensuring you tell them your callsign. If the controller responds with your callsign, you can enter the Class C airspace. If you do not hear your callsign, you cannot enter the airspace. If the controller is busy, they may ask you to wait outside the Class C airspace until they are ready.

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.

All aircraft must be equipped with a two-way radio and a Mode-C transponder to enter Class C airspace. This allows ATC to track the location and altitude of the aircraft on their radar scope. Pilots must establish and maintain communication while operating in Class C airspace.

The inner ring of Class C airspace typically extends from the surface to 4,000' above the airport, with a radius of 5NM. The outer ring typically extends from 1,200' above the airport to 4,000' above the airport, with a radius of 10NM. The outer area extends approximately 20NM from the primary Class C airspace airport.

The vertical boundaries of Class C airspace are represented by two sets of bold magenta numbers, separated by a magenta horizontal line. The top number represents the ceiling of Class C airspace in hundreds of feet MSL, and the bottom number represents the floor.

Visual and Instrument Flight Rules (VFR/IFR)

Instrument Flight Rules (IFR) consist of instrument flying, meaning the aircraft is flown using only instruments with no visual references to the outside world. IFR allows for very precise flight along a route that is more direct than the twists and turns that might be required under VFR. IFR also allows an aircraft to depart in weather that is less than required for VFR and enter clouds once the IFR clearance has been received. IFR allows pilots to get above the clouds, above terrain and obstacles, and above much of the traffic. Under IFR, air traffic control provides a watchful eye and will bring attention to any potential traffic hazards. However, it is still the responsibility of the pilot-in-command to "see and avoid" other traffic even while operating IFR whenever the aircraft is in VMC.

Pilots planning to practice maneuvers in the local area will generally remain VFR throughout the flight to maintain the flexibility required. Likewise, student pilots and their instructors will remain VFR when conducting cross-country flights for the purpose of a private pilot certificate. General aviation enthusiasts flying for fun will often fly VFR. Pilots will also be limited to VFR if their aircraft is not equipped with the required equipment for IFR flight or they do not hold the required instrument rating to act as pilot-in-command on an IFR flight plan. Some instrument-rated pilots may not be current or proficient enough to operate under IFR, especially if the weather is not conducive to VFR flight. These pilots will either opt to fly VFR or wait for the weather to improve to within their personal minimums before challenging themselves to IFR flight in IMC conditions.

Both VFR and IFR have their merits, and both can be challenging for different reasons. VFR flying is easier for student pilots to learn, and there are fewer rules. However, VFR flying is less precise, especially when it comes to navigating to smaller, less prominent locations. IFR, on the other hand, requires constant concentration and can be mentally tiring and unsettling when flying in dense clouds. Obtaining an instrument rating is imperative for most pilots, especially those whose ultimate goal is to fly commercially, as they will spend most of their time above the clouds, where there are no visual cues.

Frequently asked questions