Definition
An Airport Traffic Control Tower (ATCT) is an FAA facility, located on or adjacent to an airport, that provides air traffic control services to aircraft operating in the vicinity of that airport. The tower issues clearances and instructions for takeoff, landing, taxi, and movement within Class B, C, D, or E surface area airspace, and separates traffic on runways and in the local traffic pattern.
Plain English
The tower is the building (and the controllers inside it) that tells pilots when they can take off, land, and taxi at a controlled airport. Pilots talk to the tower by radio whenever they are arriving at, departing from, or moving on the surface of an airport that has one.
Context Anchor
Pilots encounter ATCT or Tower when using airport information, making radio calls, taxiing, taking off, landing, or operating near an airport with a control tower.
Derivation
Tower comes from older words meaning a tall structure. In aviation, the word still points to that idea, but it also means the control facility and the controllers working there, not just the physical building.
Why Pilots Care
Contacting the tower is required before entering the movement area or airspace at busy airports to prevent collisions and maintain orderly traffic flow.
Intuition Check
Do not think of Tower as only the tall building. In aviation, Tower can mean the control tower facility and the controllers who are directing airport traffic.
Example Sentence 1
After completing the run-up, the pilot called the tower and was cleared for takeoff on Runway 27.
Example Sentence 2
Tower instructed the aircraft to hold short of the runway.