Definition
An airspace of defined dimensions, above the land areas or territorial waters of a State, within which the flight of aircraft is restricted in accordance with certain specified conditions.
Plain English
A clearly marked patch of sky over a country's land or coastal waters where aircraft are only allowed to fly if they meet specific rules set by that country.
Context Anchor
You may see this term on aeronautical charts, in airspace briefings, and during flight planning near military, security, or hazardous-activity areas.
Derivation
‘Restricted’ comes from the Latin restringere, meaning ‘to bind back’ or ‘limit.’ Here it means flight is limited — not necessarily forbidden — provided the stated conditions are met. The [ICAO] tag signals this is the international definition used by the International Civil Aviation Organization, which may differ slightly from the U.S. domestic version.
Why Pilots Care
Entering without checking status or obtaining required clearance creates a safety hazard and can result in regulatory action.
Intuition Check
Do not read restricted as meaning completely forbidden. A restricted area may allow flight, but only under the stated conditions for that area.
Example Sentence 1
The pilot reviewed the chart and confirmed the restricted area along the route was inactive during the planned crossing time.
Example Sentence 2
After receiving clearance from air traffic control, the aircraft transited the restricted area without incident.