Legends

On a sectional chart the Air Defense Identification Zone is depicted by a magenta (purple) line bounded by a jagged row of dots. Along the coastline of the contiguous 48 states, generally the ADIZ is 12 nautical miles from shore, but in some areas it's only three nm from shore. In some locations the delimiting line is not shown when it coincides with International Boundary projection lines or other linear features.

The ADIZ's sole purpose is national security, and Federal Aviation Regulation Part 99 governs operations around and through it. FAR 99.3 gives the official definition: "The Air Defense Identification Zone (ADIZ) is an area of airspace over land or water in which the ready identification, location, and control of civil aircraft is required in the interest of national security."

For identification purposes, pilots must file either an IFR or Defense VFR (DVFR) flight plan before takeoff by checking the appropriate box on the standard FAA flight plan form. If pilots file a straight VFR flight plan en route (air file), they are subject to interception for positive identification when entering the ADIZ. The best way to avoid having a couple of F-16s sneak up behind you is to file a DVFR flight plan in person or by phone before departure. (For information on interception procedures, see section 5-6-2 in the Aeronautical Information Manual).

To fly in an ADIZ an aircraft must have a two-way radio and a transponder with altitude reporting (Mode C) capability. When flying in the ADIZ, VFR pilots must make position reports to ATC. Pilots on IFR flight plans use normal position reporting.

FAR 99.19 says that when flying on a DVFR flight plan, pilots must report - before they penetrate the ADIZ, - to the appropriate aeronautical facility the time, position, and altitude at which the aircraft passed the last reporting point before penetration, and the estimated time of arrival over the next appropriate reporting point along the flight route.

If there is no appropriate reporting point along the flight route, pilots must report the estimated time, position, and altitude at which they will penetrate the ADIZ at least 15 minutes before penetration. If the departure airport is within an ADIZ or so close to the ADIZ boundary that pilots can't comply with the first two requirements, they must report their time of departure, altitude, and estimated time of arrival over the first reporting point along the flight route immediately after takeoff.

Over land the pilots must be within plus-or-minus five minutes from the estimated time over a reporting point or point of penetration, and within 10 nm of the centerline of an intended track over an estimated reporting point or penetration point. Over water, the tolerance is plus or minus five minutes and 20 nm.

Finally, FAR Part 99 ADIZ regulations do not apply to the operation of any aircraft:

1. Within the 48 contiguous States and the District of Columbia, or within the State of Alaska, on a flight that remains within 10 nm of the point of departure;

2. Operating at a true airspeed of less than 180 knots in the Hawaii ADIZ or over any island, or within three nm of the coastline of any island, in the Hawaii ADIZ;

3. Operating at a true airspeed of less than 180 knots in the Alaska ADIZ while the pilot maintains a continuous listening watch on the appropriate frequency; or

4. Operating at a true airspeed of less than 180 knots in the Guam ADIZ.