The Lockheed EC-121 Warning Star was an American airborne early warning and control radar surveillance aircraft operational in the 1950s in both the United States Navy (USN) and United States Air Force (USAF). The military version of the Lockheed L-1049 Super Constellation was used to serve as an airborne early warning system to supplement the Distant Early Warning Line, using two large radomes (a vertical dome above and a horizontal one below the fuselage). It replaced the TBM-3W used by the USN. Some EC-121s were also used for signal intelligence gathering. The EC-121 was introduced in 1954 and phased out in 1978, although a single specially modified EW aircraft remained in USN service until 1982. The USN versions when initially procured were designated WV-1 (PO-1W), WV-2, and WV-3. The USAF Warning Stars served during the Vietnam War both as electronic sensor monitors and as a forerunner to the Boeing E-3 Sentry AWACS. USAF aircrews adopted its civil nickname, "Connie" (diminutive of Constellation) as reference, USN aircrews used the nickname "Willie Victor". Development Since 1943, the Lockheed Constellation had been in USAAF service as the C-69. The use of the Constellation by the USN for patrol and airborne early warning duties was first investigated in 1949, when the USN acquired two Lockheed L-749 Constellations. First flown on 9 June 1949, the PO-1W carried large, long-range radars in massive radomes above and below the fuselage. As the radomes possessed considerably more side area, the vertical stabilizers of the PO-1W had to be enlarged. After the PO-1W (redesignated WV-1 in 1952) had proved that operating large radars on aircraft was possible, the USN ordered the WV-2 based on the L-1049 Super Constellation. The WV-1s were transferred to the Federal Aviation Agency in 1958–1959. The WV-2/EC-121D was initially fitted with a dorsal AN/APS-45 height finder and a ventral AN/APS-20 search radar. These were later upgraded to AN/APS-103 and AN/APS-95 radars, although not simultaneously. The crew commonly numbered 18, six officers (two pilots, two navigators, and two weapons controllers) and 12 enlisted (two flight engineers, one radio operator, two crew chiefs, five radar operators, and two radar technicians). However, when North Korea shot down a Navy EC-121 in 1969, a crew of 31 was on board. Orders were placed totaling 142 PO-2W Constellations based on the Lockheed L-1049 Super Constellation, with deliveries beginning in 1953. The PO-2W was redesignated WV-2 in 1954. In 1962, with