Definition of Block Altitude
Block altitude is a term used by Air Traffic Control (ATC) to designate a specific range of altitudes within which aircraft are allowed to deviate. This is typically given as a block of altitudes, i.e. “Maintain block altitude of 9 to 11 thousand.”
This term is commonly used in situations where aircraft are flying in crowded airspace, such as near major airports, to aid in maintaining separation between aircraft. By allowing aircraft to deviate within a certain range of altitudes, ATC can better manage traffic flow and reduce the risk of mid-air collisions.
Block altitude is also used in situations where weather conditions are unpredictable, such as during thunderstorms. Pilots are given a block altitude range within which to fly, allowing them to navigate around dangerous weather and avoid turbulence.