Definition
An area of airspace over land or water within which the ready identification, location, and control of all civil aircraft is required in the interest of national security. Aircraft operating in or transiting an ADIZ must file a flight plan, maintain two-way radio communication, and continuously squawk an assigned transponder code.
Plain English
A buffer zone of airspace, usually near a country's borders or coastlines, where aircraft must identify themselves before entering. If you fly through one without filing a flight plan and talking to ATC, the military may treat you as a potential threat.
Context Anchor
You may see this term during flight planning for routes near U.S. coastlines, borders, or other security-sensitive areas.
Derivation
The term comes straight from its function: a 'zone' (defined area) where 'air defense' (military protection from airborne threats) requires 'identification' of every aircraft. The phrase dates to the early Cold War, when the U.S. and Canada set up these zones to detect unknown aircraft approaching North America.
Why Pilots Care
Entering without following required procedures can result in interception by military aircraft or enforcement action.
Intuition Check
An air defense identification zone is not automatically a no-fly area. It means you may need to identify yourself and follow specific procedures before entering or operating there.
Example Sentence 1
Before departing on the coastal route to the Bahamas, the pilot filed a DVFR flight plan to comply with ADIZ requirements.
Example Sentence 2
Aircraft flying near the coast must file a DVFR flight plan when operating inside the air defense identification zone.