Final answer:
Air Traffic Control (ATC) is the agency responsible for the control of airborne aircraft, except for those managed by the Combat Direction Center or a Principal Air Control Authority.
Step-by-step explanation:
The agency responsible for the control of airborne aircraft, except those under the control of the Combat Direction Center (CDC) or a Principal Air Control Authority (PRIFLY), is known as Air Traffic Control (ATC).
ATC is a service provided by ground-based controllers who direct aircraft on the ground and through controlled airspace, and can provide advisory services to aircraft in non-controlled airspace. The responsibility of ATC typically includes ensuring the safe, orderly, and expeditious flow of air traffic.