Definition
An air traffic control instruction directing a pilot to climb to, descend to, or maintain a specific altitude expressed in feet above mean sea level (MSL) or, where applicable, as a flight level. The assigned altitude becomes the cleared altitude the pilot must fly until ATC issues a new assignment.
Plain English
The altitude that ATC has told you to fly. Once they assign it, you stay at that altitude until they tell you something different.
Context Anchor
You will hear or read altitude assignments in instrument clearances, climb and descent instructions, and air traffic control communications during instrument flight.
Derivation
Altitude comes from the Latin word altus, meaning “high.” Assignment comes from words meaning “to mark out” or “to allocate.” Together, the phrase points to a specific height that has been allocated to an aircraft.
Why Pilots Care
Ensures vertical separation between aircraft and reduces the risk of collision or wake encounters.
Intuition Check
Do not read “assignment” as a casual suggestion. In this context, an altitude assignment is the altitude air traffic control expects the aircraft to fly unless a new clearance or instruction changes it.
Example Sentence 1
Center issued an altitude assignment of 8,000 feet, and the pilot read back, "Maintain eight thousand."
Example Sentence 2
After departure the pilot read back the altitude assignment of 5000 feet before entering the departure corridor.