Definition
An air traffic control position, and its associated radio frequency, responsible for issuing IFR clearances and certain other pre-departure instructions to aircraft before they taxi from the gate or ramp.
Plain English
It is the controller you call before you start moving on the ground to receive your route, altitude, and other instructions for your flight.
Context Anchor
You encounter clearance delivery before departure, either on a published radio frequency, by phone, or through flight service when a direct air traffic control frequency is not available.
Derivation
From 'clearance' (permission granted by ATC to proceed under specified conditions) and 'delivery' (the act of handing something over). The position exists to deliver the clearance to the pilot before any other ground movement begins.
Why Pilots Care
It ensures the pilot receives an approved route and altitude assignment that keeps the flight safely separated from other traffic from the moment of departure.
Intuition Check
Do not assume clearance delivery means permission to take off. It delivers the departure clearance; a separate takeoff clearance comes from the tower, or the pilot departs under the correct non-towered airport procedure.
Example Sentence 1
Before requesting taxi, the pilot called clearance delivery and copied the IFR clearance to their destination.
Example Sentence 2
At a busy airport, clearance delivery issued a different departure routing than the one filed to avoid traffic congestion.