the.com/air traffic control

means The ground-based system of people and radar that tracks aircraft and directs pilots to keep planes safely separated and moving efficiently through the sky.

from A 20th-century coinage, born directly from need: as powered flight matured and airports filled with traffic, the aviation industry borrowed the everyday word 'traffic' — already used for ships and street vehicles — and applied it to airplanes. Early air traffic control grew out of simple airfield flagmen and light signals in the 1920s-30s, then radio, then radar, each generation adding a layer of 'control' to match the growing crowd in the sky. The phrase itself simply describes what it does: controlling traffic, just three dimensions up.