Definition
A defined area of airspace over land within which the ready identification, location, and control of all civil aircraft is required in the interest of national security. Aircraft operating in or penetrating an ADIZ must file a flight plan, maintain two-way radio communication, and follow specific position-reporting and transponder requirements established by federal regulation.
Plain English
A patch of airspace over land where the government needs to know who you are, where you are, and where you're going — for national security reasons. If you're flying through one, you have to file a flight plan, talk to ATC on the radio, and squawk an assigned transponder code.
Context Anchor
Pilots encounter this term when planning flights near national security airspace, border areas, or other places where special aircraft identification rules apply.
Derivation
From 'air defense' (military protection of airspace) plus 'identification zone' (an area where you must be identified). The 'land based' qualifier distinguishes it from coastal or distant early warning ADIZs that sit over water.
Why Pilots Care
Failure to comply can result in interception by military interceptors and possible enforcement action.
Intuition Check
Do not read Land Based as meaning the aircraft must be based at a land airport. Here it means the identification zone is associated with land areas and national air defense needs.
Example Sentence 1
Before crossing the southern ADIZ on his flight to Brownsville, he filed a DVFR flight plan and got a discrete transponder code from ATC.
Example Sentence 2
The controller asked the pilot to squawk a discrete code upon nearing the ADIZ — Land Based Air Defense Identification Zone.