Definition
A defined volume of airspace, typically described by a range of altitudes between two specified levels, within which an aircraft is cleared to operate. Air traffic control may issue a block altitude clearance authorizing flight anywhere between, for example, 10,000 feet and 12,000 feet, giving the pilot freedom to climb, descend, or maneuver within those limits without further clearance.
Plain English
A chunk of sky with a defined top and bottom that a controller has cleared you to use. You can move up and down inside it freely, but you must stay within those limits.
Context Anchor
Seen in instrument flying examples, ATC instructions, training areas, and procedure descriptions where an aircraft must stay within a defined part of the sky.
Derivation
‘Block’ here carries its everyday sense of a solid, bounded section — like a city block, a bounded area you stay within. Applied to airspace, it means a bounded slice of sky with clear edges.
Why Pilots Care
Unauthorized entry risks mid-air conflict, regulatory violation, or loss of separation.
Grounding Statement
Picture invisible walls, a floor, and a ceiling around part of the sky; that enclosed area is the block of airspace.
Intuition Check
“Block” does not mean an obstacle here. It means a bounded portion of sky that has been defined for a particular use.
Example Sentence 1
ATC cleared the training flight for a block of airspace between 6,000 and 8,000 feet so the student could practice steep turns and altitude changes.
Example Sentence 2
Controllers released the block of airspace after the military exercise ended.