Definition
An authorization issued by air traffic control (ATC) permitting an aircraft to leave its currently assigned altitude and descend to a specified lower altitude, often along a defined route or profile. The clearance specifies the altitude to descend to and may include restrictions such as crossing altitudes, speed, or the point at which the descent must begin or be completed.
Plain English
Permission from ATC to come down from your current altitude to a lower one they specify. You don't start down until they say so, and you stop at the altitude they give you.
Context Anchor
Heard in radio communications during instrument flight, especially before an approach or while being guided toward an airport.
Derivation
“Descent” comes from a word meaning “to climb down.” “Clearance” in aviation means official permission from air traffic control, not simply that the path is free of obstacles.
Why Pilots Care
It maintains separation from other traffic and terrain while ensuring the descent complies with ATC instructions and the published procedure.
Intuition Check
Do not read “clearance” as “the airspace below is automatically safe.” Here, it means air traffic control has authorized the descent, and the pilot must still follow the stated altitude limits and maintain safe aircraft control.
Example Sentence 1
About 80 miles from the destination, the controller issued a descent clearance: "Cessna 32X, descend and maintain 8,000."
Example Sentence 2
After receiving the descent clearance the pilot reduced power and began a controlled descent.