How Air Traffic Control Works


Air traffic control oversees every move a plane makes, from gate to gate.

Hollywood’s depiction of air traffic control is far from accurate: The lone person in the control tower handling everything from Tom Cruise’s Top Gun fly–by to assigning holding patterns to aircraft hundreds of miles away in Die Hard 2 simply does not exist. Air traffic control (ATC) is a widely distributed network that includes airspace area control centres, ground controllers, clearance delivery and apron controllers.

Before we go anywhere, a flight plan must be filed into the ATC system – be it for a small Cessna or a Boeing 777. Air Canada’s flight dispatch team determines the routes and files flight plans, so the first time an Air Canada pilot talks to ATC is to contact clearance delivery to “confirm” the flight plan. Confirmation comes from the local airport tower, but it is most often transmitted via text message over a data link. Our next communication is to the ramp controller, who clears us for pushback out of the gate. We then contact “ground,” which is actually in the tower next to the tower controller, for taxi instructions. Then it’s over to “tower” for takeoff clearance, and finally we check in with “departure” – which is in another building frequently off airport premises. As the flight traverses regional and national airspaces, we converse with different area centres along the way.

Another misconception of air traffic control is the image of the harried environment of the control tower. In reality (and backed up by what I hear on the radios) the atmosphere is fast–paced but calm and the controllers are methodical and composed. They handle requested heading changes (to avoid thunderstorms), altitude changes (to find smooth air) and shorter route requests (to save time) as coolly as a circa–1986 Tom Cruise.

April 21, 2021

High Frequency

An infographic depicting the minimum amount of times a pilot connects with an air traffic controller
  • 20 — The number of required radio–frequency changes during a 300–mile flight from Toronto to New York.

  • Nav Canada oversees traffic in Canada’s airspace, which is divided into seven area control centres: Gander, Moncton, Montreal, Toronto, Winnipeg, Edmonton and Vancouver.

  • Pilots contact ATC to get clearances – authorizations for a pilot to perform a task – whereas ATC will call pilots with instructions, which are to be acted upon without delay.

  • There’s always been a friendly rivalry between pilots and controllers. My air traffic control friends remind me that they get to tell us pilots where to go.

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Portrait of Air Canada's Captain Doug Morris
Photo: Reynard Li

Doug Morris is an author, meteorologist, instructor and Air Canada captain on the Boeing 787.