Tracking the MiGs: EC-121 Airborne Early Warning EC-121s played a key role by monitoring airborne North Vietnamese MiGs and guiding USAF fighters to intercept them. Orbiting securely outside the border, EC-121 crews used the aircraft's radar and enemy radio communications to detect and locate MiGs within North Vietnamese airspace. These operations began in the spring of 1965 under the code name BIG EYE (later named COLLEGE EYE and DISCO), and continued beyond the end of the war. Click here to return to the Air-to-Air Combat Overview. Find Out More Related Fact Sheets Lockheed EC-121D Constellation Note: The appearance of hyperlinks does not constitute endorsement by the National Museum of the USAF, the U.S. Air Force, or the Department of Defense, of the external website, or the information, products or services contained therein.