Definition
An area of airspace over land or water in which the ready identification, location, and control of all civil aircraft (with certain exceptions) is required in the interest of national security. Aircraft operating in or transiting an ADIZ must file an appropriate flight plan, maintain two-way radio communication, and have an operating transponder. ADIZs typically exist along U.S. coastal borders and in other strategic locations.
Plain English
A defined slice of airspace where the U.S. military needs to know who you are before you enter. To fly through it, you must file a flight plan in advance, stay in radio contact, and have your transponder on so you can be identified on radar.
Context Anchor
Pilots encounter ADIZ procedures when planning flights near certain U.S. coastal or border areas, especially when flying toward the United States from offshore or from another country.
Derivation
Air Defense refers to the military mission of protecting national airspace. Identification Zone means a defined area where aircraft must be identified before being allowed to proceed. The name describes the function: a zone where you must be identified for air defense purposes.
Why Pilots Care
Failing to follow required procedures can result in interception by military aircraft.
Intuition Check
Do not treat an ADIZ as simply another restricted area. The main issue is identification: authorities must be able to identify and track the aircraft before it enters or operates in the zone.
Example Sentence 1
Before departing on the cross-country flight along the coast, the pilot filed a DVFR flight plan because the route crossed an ADIZ.
Example Sentence 2
All aircraft must be on an active flight plan when operating inside an ADIZ.