Definition
Air traffic control facilities located on an airport that issue clearances and instructions to aircraft operating on the movement area (runways and taxiways) and within the airport's surrounding airspace, sequencing arrivals, departures, and ground movements to keep traffic safely separated.
Plain English
The staffed building at an airport — usually the tall one with windows on top — where controllers watch the airport and nearby airspace and tell pilots when they can take off, land, and taxi.
Context Anchor
You see this term when an airport has an operating air traffic control tower and pilots must contact the tower for taxi, takeoff, landing, or arrival instructions.
Derivation
From Latin contra rotulus, 'against the roll' — originally a checking record kept against the official one. 'Control' came to mean directing or regulating. A control tower is literally a tower from which traffic is regulated.
Why Pilots Care
Pilots must establish radio contact with the control tower before entering its airspace or moving on the airport to receive clearances and avoid traffic conflicts.
Intuition Check
Do not think of a control tower as just a tall lookout or airport office. It is the active air traffic control position responsible for directing traffic on and near that airport.
Example Sentence 1
Before taxiing for departure, the pilot called the control tower for a taxi clearance to the active runway.
Example Sentence 2
After landing, the pilot followed control tower instructions to taxi to the ramp without conflicting with other aircraft.