purpose was to gain better low-altitude coverage in the Hanoi area. At the end of the month, Disco was also integrated into Teaball control center, a highly classified system established to collate all signal intelligence on North Vietnamese air activity gathered by all sources, including nonmilitary. Disco was used as a conduit through which warnings and control vectors were given, but the delay in Teaball acquiring the information and relaying it through Disco (often using an unreliable radio relay KC-135A Combat Lightning aircraft operating under callsign Luzon) cancelled out its value for use in "real time", and the fact that its existence was kept from US aircrews damaged its credibility. Teaball received direct comms capability, but experienced transmission failures with frustrating frequency. Disco remained the primary backup controller, but its usefulness remained limited because it directly controlled only MiGCAP missions and could only provide its information to strike, chaff, and escort forces via the "Guard" frequency. On 15 August 1973, Disco EC-121s flew their final combat mission and on 1 June 1974, Det.1 was permanently withdrawn from Southeast Asia. Between 1965 and 1973, the EC-121s flew 13,921 combat missions, more than 98,000 accident-free flying hours, assisted in the shoot-down of 25 MiGs, and supported the rescue of 80 downed flyers. No Big Eye, College Eye, or Disco aircraft were lost. Batcat During the Vietnam War, some 40 EC-121s were modified from USN WV-2 and WV-3 early warning Constellations for use with ground sensors to detect enemy troop movements along the Ho Chi Minh Trail, and 25 were deployed to Korat RTAFB as a part of Operation Igloo White. The resulting EC-121R configuration was nicknamed the Batcat. Two Batcats were lost during the war, with the loss of 22 crewmen, one in a takeoff accident during a thunderstorm in April 1969, the other in September 1969, in a landing accident. Four Thai civilians were also killed in the second crash. Batcat EC-121s were camouflaged in standard tree-color Southeast Asia scheme, while the College Eye/Disco early warning aircraft were not. BatCat missions were 18 hours in length, with 8 hours on station at one of 11 color-coded orbits used during their 5-year history, three of which were over South Vietnam, six over Laos, one over Cambodia, and one over the Gulf of Tonkin. EC-121Rs were operated by the 553d and 554th Reconnaissance Squadrons of the 553d Reconnaissance Wing, between October 1967 and