Definition
An authorization issued by air traffic control (ATC) for an aircraft to proceed under specified conditions within controlled airspace. A clearance permits a pilot to take a specific action — such as taking off, landing, taxiing, entering a runway, or flying a route or altitude — and is binding once accepted.
Plain English
Permission from air traffic control to do something specific, like take off, land, or fly a particular route. Once you accept it, you must follow it.
Context Anchor
Pilots hear and read clearances in radio calls, ground movement instructions, takeoff and landing instructions, and route or altitude instructions from air traffic control.
Derivation
From the verb 'clear,' meaning to make a path free of obstruction. A clearance is, literally, ATC clearing the way for the aircraft to proceed.
Why Pilots Care
Operating without the required clearance in controlled airspace violates regulations and can create mid-air or runway conflicts.
Intuition Check
Do not assume “clearance” means everything is automatically safe or approved without limits. It means permission for a specific action under the conditions stated by air traffic control.
Example Sentence 1
The pilot received clearance to taxi to runway 27 via taxiway Alpha.
Example Sentence 2
We called clearance delivery to receive our IFR clearance before departure.