The EC-121, originally designated as the RC-121, is a radar-picket modification of the USAF C-121 passenger airplane which evolved from the Lockheed "Constellation" commercial transport. The massive radomes above and below the fuselage carry six tons of electronic gear. These aircraft entered service with the Air Defense Command in 1953, flying patrols off the U.S. coasts as an aerial extension of the Distant Early Warning (DEW) Line. The Air Force ordered 82 RC-121s between 1951 and 1955, 72 of which were -Ds.

In Southeast Asia, these unarmed radar aircraft aided in downing enemy planes, directed U.S. aircraft to their aerial refueling tankers, and guided rescue planes to downed pilots.

Warner Robins Air Logistics Center managed the entire repair and logistics support for the EC-121's extensive electronic equipment and propeller systems throughout the aircraft's service life. The EC-121 on display is actually a U.S. Navy EC-121K version, and retired in July 1979. It was flown to the Museum in 1987 for display.