Air traffic controllers typically do the following:

• Monitor and direct the movement of aircraft on the ground and in the air
• Control all ground traffic at airport runways and taxiways
• Issue landing and takeoff instructions to pilots
• Transfer control of departing flights to other traffic control centers and accept control of arriving flights
• Inform pilots about weather, runway closures, and other critical information
• Alert airport response staff in the event of an aircraft emergency

Air traffic controllers’ primary concern is safety, but they also must direct aircraft efficiently to minimize delays. They manage the flow of aircraft into and out of the airport airspace, guide pilots during takeoff and landing, and monitor aircraft as they travel through the skies. Air traffic controllers use radar, computers, or visual references to monitor and direct the movement of the aircraft in the skies and ground traffic at airports.

Controllers usually manage multiple aircraft at the same time and must make quick decisions to ensure the safety of aircraft. For example, a controller might direct one aircraft on its landing approach while providing another aircraft with weather information.

The following are examples of types of air traffic controllers:

Tower controllers direct the movement of vehicles, including aircraft, on runways and taxiways. They check flight plans, give pilots clearance for takeoff or landing, and direct the movement of aircraft and other traffic on the runways and in other parts of the airport. Most work from control towers, observing the traffic they control. Tower controllers manage traffic from the airport to a radius of 3 to 30 miles out.

Approach and departure controllers ensure that aircraft traveling within an airport’s airspace maintain minimum separation for safety. They give clearances to enter controlled airspace and hand off control of aircraft to en route controllers. Approach and departure controllers use radar equipment to monitor flight paths and work in buildings known as Terminal Radar Approach Control Centers (TRACONs). They also inform pilots about weather conditions and other critical notices. Terminal approach controllers assist the aircraft until it reaches the edge of the facility’s airspace, usually about 20 to 50 miles from the airport and up to about 17,000 feet in the air.

En route controllers monitor aircraft once they leave an airport’s airspace. They work at air route traffic control centers located throughout the country, which typically are not located at airports. Each center is assigned an airspace based on the geography and air traffic in the area in which it is located. As an airplane approaches and flies through a center’s airspace, en route controllers guide the airplane along its route. They may adjust the flight path of aircraft to avoid collisions and for safety in general. Route controllers direct the aircraft for the bulk of the flight before handing to terminal approach controllers.

Some air traffic controllers work at the Air Traffic Control Systems Command Center, where they monitor traffic within the entire national airspace. When they identify a bottleneck, they provide instructions to other controllers, helping to prevent traffic jams. Their objective is to keep traffic levels manageable for the airports and for en route controllers.