Air Defense Identification Zone (ADIZ)
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. The Canadian ADIZ when discussed separately is known as the CADIZ. 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. 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 June 25, 1950, North Korea launched an invasion of South Korea, drawing the United States into a war that would last for three years. 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. 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. 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. With the establishment of ADIZ, unidentified aircraft approaching North American airspace would be interrogated by radio. If the radio interrogation failed to identify the aircraft, the Air Force launched interceptor aircraft to identify the intruder visually. In addition, the Air Force received Army cooperation. 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.
The joint US/Canadian ADIZ, which is almost exclusively over water, serves as a national defense boundary for aerial incursions. 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). 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). In the United States, the FAA handles the requests of international aircraft and Transport Canada handles Canadian requests.
Any aircraft flying in these zones without authorization may be identified as a threat and treated as an enemy aircraft, potentially leading to interception by fighter aircraft. Unless otherwise authorized by ATC, no person may operate an aircraft into, within, or across an ADIZ unless that person has filed a flight plan with an appropriate aeronautical facility (14 CFR 99.11(a)). Unless otherwise authorized by ATC, no person may operate an aircraft into, within, or across an ADIZ unless that aircraft is equipped with a coded radar beacon transponder and automatic pressure altitude reporting equipment having altitude reporting capability that automatically replies to interrogations by transmitting pressure altitude information in 100-foot increments (14 CFR 99.13(c)).
If intercepted, fighter aircraft may attempt to establish contact via radio on UHF 243.0 and/or VHF 121.5. ICAO visual signals are established in Annex 2, “Rules of the Air”. Signals initiated by intercepting aircraft include rocking aircraft & flashing navigational lighting, after acknowledgement, slow level turn to desired heading. The intercepting aircraft circles the airport, lowers landing gear, and overflies runway in the direction of landing. Also, at night turn the landing lights on. Immediate compliance with fighter aircraft instructions is mandatory.
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