If you’ve ever had the opportunity to listen to Air Traffic Control (ATC) communicating with pilots over a radio scanner, you’ve probably thought they’re speaking in some English-hybrid, coded language. In many ways, you’re right. While English is the globally accepted language for ATC, there are many special codes and terms that are used in aviation, such as the phonetic alphabet (Alpha, Bravo, Charlie, Delta, Echo, and so on). This allows consistency worldwide as flights move through numerous airspaces and speak to multiple controllers throughout their journey.
Even on the shortest of flights, your pilots are likely talking to no less than seven separate air traffic controllers from gate to gate. On longer flights, this number could easily double. This happens because each controller is typically only working one section of an airport, or one sector of an airspace.
During the preflight procedures, often before boarding is even complete, your pilot will contact Clearance Delivery, known as “Clearance.” The pilot radios the clearance controller with their flight number and destination and the controller replies that they’re cleared to the destination as their flight plan indicates, or if there have been any changes implemented to their flight plan by the FAA. Clearance also often gives the pilot an initial altitude to expect after takeoff, the cruising altitude to expect and the frequency they’ll need to contact the departure controller after takeoff. When traveling to a busier airspace, clearance may also give the pilot a specific window of time during which to takeoff in order to arrive at the flight’s pre-sequenced time.
When your flight is ready to leave the gate, your pilot contacts Ground Control, known simply as “Ground.” The ground controller will give them permission to push back onto a given taxiway or another designated location. Ground controllers are responsible for all movements along airport taxiways. At busier airports like Atlanta or Charlotte, the ramp areas (the paved area between gates and taxiways) each have their own controllers that direct the movement of airplanes into and out of gates. After being cleared by ramp or ground controllers to push back and doing so, the pilot notifies the ground controller when he or she is ready to taxi to the runway and is given clearance to do so.
Here at Asheville and in other mid-sized airports, your departure runway will always be dictated almost exclusively by wind direction. Aircraft always takeoff and land into the wind, as best as the runway layout of an airport permits. At busier airports with multiple runways, the direction into which you’ll be exiting the airspace also determines the runway to which you are assigned. For example, when departing Atlanta and heading north, west, or any direction in between, flights generally use the runway on the north side of the field. South and eastbound flights use the southern runway. When nearing the end of the departure runway, the pilots switch from ground to Tower Control, commonly known as “tower” and notify the tower controller that they’re prepared to depart.
Tower controllers are the controllers that most everyone is thinking of when they think of ATC — thanks in part to films like Pushing Tin. Tower controllers are positioned in an airport’s control tower and are responsible for all movements on an airport’s runway, which mostly consist of takeoff and landing clearances. Takeoff clearance usually includes a heading (direction) to fly, or a waypoint (invisible directional marker) to turn towards, along with an initial altitude to climb to and not exceed.
Very shortly after becoming airborne, the control tower tells your pilots to contact Departure. Departure controllers, along with approach controllers, make up the Terminal Radar Approach Control (TRACON). They’re responsible for all aircraft within 30 to 50 miles, and in some cases up to 100 miles, of an airport. Departure handles all departing flights from shortly after takeoff until they are leaving the airport’s airspace. Approach handles all arrivals from airspace entry until they are close enough to the airport to be handed to the control tower. Pilots only spend a few minutes communicating with departure before out-climbing the airspace and being directed to contact an Area Control Center, known simply as “Center.”
Center control facilities house numerous controllers and are responsible for controlling aircraft that are en route over large regions. There are only 20 centers to cover all of the U.S. airspace. A flight from AVL to Charlotte will only communicate with Atlanta Center, but a flight to Chicago will communicate with Atlanta, Indianapolis and Chicago Center while enroute. Once your flight has contacted center, they are cleared to their final cruising altitude, traffic permitting. Center is responsible for your flight until you’re close enough to your destination’s airspace to be handed to the approach controller.
At this point, the entire progression of controllers essentially goes in reverse. Through approach, landing, taxi and parking, your pilots will communicate with Center, Approach, Tower, Ground and possibly Ramp — in that order.
While this may seem like an intricate web of communication, most transmissions are very brief and odds are your flight will never have to deviate from its original flight plan in any way. Between flight-planning technology, aircraft navigation abilities and aircraft sequencing technology, most adjustments that controllers do have to make are minor, even in the busiest of airspaces. Controllers are yet another piece in the system that keeps air traffic moving safely and efficiently around the world!