Definition
An authorization issued by air traffic control (ATC) for an aircraft to proceed under specified traffic conditions within controlled airspace. The clearance is intended to prevent collisions between known aircraft and authorizes a specific route, altitude, and set of instructions the pilot must follow.
Plain English
Permission from air traffic control to fly a particular route, at a particular altitude, under particular instructions. It tells the pilot what they are allowed to do, and they must follow it.
Context Anchor
Pilots encounter this term in radio communications, flight planning, departures, arrivals, and anytime air traffic control gives approval for a specific aircraft action.
Derivation
Clearance' comes from the verb 'to clear' — to make free of obstruction. An ATC clearance clears the pilot's path through controlled airspace by confirming no conflicting traffic is being routed the same way.
Why Pilots Care
Pilots must receive and follow this authorization to legally enter controlled airspace and maintain safe separation from other traffic.
Intuition Check
Do not read “clearance” as just “enough space” or “everything is safe.” In this context, it means official permission with specific conditions attached.
Example Sentence 1
Before departure, the pilot copied down the IFR clearance: cleared to the destination airport via the filed route, climb and maintain 6,000.
Example Sentence 2
Before entering Class C airspace, the student pilot requested and received an air traffic control clearance from approach control.