Definition
An ATC clearance, issued using the word 'cruise,' that authorizes a pilot to fly at any altitude from the minimum IFR altitude up to and including the altitude specified in the clearance. The pilot may level off at any intermediate altitude within this block, and may climb or descend within it without further ATC authorization. However, once the pilot reports leaving an altitude, that altitude may not be returned to without a new clearance. A cruise clearance also authorizes the pilot to execute an approach at the destination airport.
Plain English
ATC is giving you a range of altitudes to work within, from the lowest legal IFR altitude up to the one they named. You can pick where to fly inside that range, change altitude when you want, and start your approach when you arrive — all without asking again. The catch: once you leave an altitude and tell ATC, you can't go back to it without permission.
Context Anchor
Used in IFR clearances, especially when ATC gives the pilot more freedom to choose altitude during en route flight or arrival.
Derivation
“Cruise” originally meant to sail or travel about, and in aviation it often suggests steady flight. “Clearance” means official permission from air traffic control. Together, the phrase means ATC is giving permission to continue the flight with more altitude choice than a normal single-altitude clearance.
Why Pilots Care
Gives the pilot freedom to select the best altitude for weather, winds, or turbulence without requesting step climbs or new clearances.
Intuition Check
Do not read “cruise clearance” as simply “permission to fly normally in cruise.” In IFR flying, it is a specific ATC clearance that gives a permitted altitude range and can also include permission to fly the approach at the destination.
Example Sentence 1
ATC issued, 'Cruise six thousand,' allowing the pilot to operate at any altitude from the minimum IFR altitude up to and including 6,000 feet.
Example Sentence 2
With the cruise clearance in hand we descended to 8,000 feet for better fuel economy without further radio calls.