Plain English Meaning
A set route that aircraft follow in the air around an airport so everyone takes off, lines up, and lands in the same orderly way. Think of it as a shared lane system in the sky near the runway.
Full Definition
Standardized rectangular flight paths flown by aircraft around an airport when arriving for landing or departing after takeoff. The pattern consists of defined legs (upwind, crosswind, downwind, base, and final) flown at a specified altitude and direction to provide an orderly, predictable flow of traffic in the airspace surrounding the runway.