Definition
Specific altitudes issued by air traffic control (ATC) that a pilot is required to fly or maintain during an IFR flight. Altitude assignments are part of the ATC clearance and are a primary tool for vertical separation between aircraft.
Plain English
When you are flying on an IFR flight plan, ATC tells you exactly what altitude to fly. That instruction is your altitude assignment, and you must fly it unless ATC changes it or you get permission to do something else.
Context Anchor
Seen in instrument procedures, controller clearances, and discussions of how aircraft are kept safely separated in instrument flight.
Derivation
Altitude comes from a Latin word meaning high. Assignment comes from words meaning to mark out or allot something. Together, the phrase means a height that has been allotted to the aircraft for that part of the flight.
Why Pilots Care
Proper compliance prevents mid-air conflicts and ensures legal separation from other traffic.
Intuition Check
Do not read assignment as a loose suggestion or a classroom task. In this context, an altitude assignment is an altitude the pilot is expected to follow unless another clearance or procedure changes it.
Example Sentence 1
After takeoff, the controller issued an altitude assignment of 8,000 feet, and the pilot leveled off and reported reaching it.
Example Sentence 2
After takeoff the pilot received a new altitude assignment to climb and maintain 5000 feet.