While approaching and crossing the North American ADIZ, aircraft must have an operational radar transponder and maintain two-way radio contact (see 14 CFR 99.9 & 99.13). Any aircraft that wishes to fly in or through the boundary must file either a Defense Visual Flight Rules (DVFR) flight plan or an Instrument Flight Rules (IFR) flight plan before crossing the ADIZ (14 CFR 99.11). The joint US/Canadian ADIZ, which is almost exclusively over water, serves as a national defense boundary for aerial incursions. The commander of the Army's Antiaircraft Artillery Command allowed the Air Force to take operational control of the gun batteries as part of a coordinated defense in the event of attack. In addition, the Air Force received Army cooperation. If the radio interrogation failed to identify the aircraft, the Air Force launched interceptor aircraft to identify the intruder visually. With the establishment of ADIZ, unidentified aircraft approaching North American airspace would be interrogated by radio. As a result, an air defense command and control structure began to develop and Air Defense Identification Zones (ADIZ) were staked out along the nation's frontiers. In the process of placing forces on heightened alert, the Air Force uncovered major weaknesses in the coordination of defensive units to defend the nation's airspace. Believing that the North Korean attack could represent the first phase of a Soviet-inspired general war, the Joint Chiefs of Staff ordered Air Force air defense forces to a special alert status. On June 25, 1950, North Korea launched an invasion of South Korea, drawing the United States into a war that would last for three years. That ADIZ is located about 200 miles from the shore and is intended to give plenty of time to detect the aircraft and determine its identify. On any given day there are about 2,500 aircraft that fly into the Air Defense Identification Zone of both the United States and Canada. The Canadian ADIZ when discussed separately is known as the CADIZ. In North America, the US and Canada are surrounded by an Air Defense Identification Zone (ADIZ), which is jointly administered by the civilian air traffic control authorities and the militaries of both nations, under the auspices of the North American Aerospace Defense Command or NORAD.

Air defense zone