Definition
A person authorized to provide air traffic control services, including the separation, sequencing, and safe movement of aircraft within their assigned area of responsibility.
Plain English
The trained professional on the ground who talks to pilots by radio and tells them what to do to keep aircraft safely separated from each other and moving in an orderly way.
Context Anchor
Pilots encounter controllers on the radio during taxi, takeoff, climb, cruise, descent, approach, and landing, especially when operating at controlled airports or in controlled airspace.
Derivation
From the verb "to control," meaning to direct or regulate. In aviation, the controller directs traffic — not by physically steering aircraft, but by issuing instructions and clearances that pilots follow.
Why Pilots Care
Controllers maintain safe separation between aircraft, issue critical instructions, and prevent collisions in busy airspace.
Intuition Check
Do not read controller as just any person who is generally in charge. In FAA use, a controller is specifically an authorized air traffic control person providing service to pilots.
Example Sentence 1
The controller cleared us for takeoff on runway 27 and instructed us to contact departure once airborne.
Example Sentence 2
We contacted the departure controller for a vector to join the airway.