Constellation негізіндегі әуе ерте ескерту және басқару ұшағы

Airborne early warning and control aircraft based on the Constellation airframe

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".

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). The EC 121K was also operated by Training Squadron 86 (VT 86) at NAS Glynco, Georgia, for training of student naval flight officers destined to fly both the EC 121 and the Grumman E 2 Hawkeye. At NAS Glynco's closure, VT 86 transferred to NAS Pensacola, Florida, in 1973, the squadron's last EC 121 was also flown to NAS Pensacola, being stored in the collection of the National Museum of Naval Aviation, where it still remains. A single aircraft became an NC 121K, the electronic warfare variant assigned to Tactical Electronic Warfare Squadron 33 (VAQ 33) at NAS Key West, Florida. The aircraft was the last EC 121 in operational service, flying until 25 June 1982. The USAF received 10 RC 121C and 74 EC 121D Warning Stars also based on the L 1049, beginning with diversions from the Navy contracts in October 1953. The 10 RC 121Cs became trainers, designated TC 121C. Between 1966 and 1969, 30 retired USN EC 121s were transferred to USAF and converted in EC 121Rs as sensor monitoring aircraft. Of the 74 EC 121s, 42 were converted to the EC 121H upgrade beginning in 1962, and in 1969, 15 of the remaining EC 121Ds and seven of the EC 121Hs were further upgraded into the final operational variant, the EC 121T, serving as an AWACS prototype in Southeast Asia in 1972.

WV 2s, redesignated EC 121s in 1962, served from 1954 to 1965 in two "barrier" forces, one off each coast of the North American continent. The barrier forces consisted of five surface picket stations each manned by radar destroyer escorts and an air wing of WV 2s/EC 121s that patrolled the picket lines at 1,000–4,000 m (3,000–12,000 ft) altitude in 6 to 20 hour missions. Their objective was to extend early warning coverage against surprise Soviet bomber and missile attacks as an extension of the DEW Line. In April 1954, the first Lockheed Super Constellation (Model 1049C), WV 2 BuNo. 128323, was received at NAS Barbers Point by Airborne Early Warning Squadron One (VW 1). The Atlantic Barrier (BARLANT) consisted of two rotating squadron detachments sourced from AEW Squadron Thirteen (VW 13) and AEW Squadron Fifteen (VW 15) from NAS Patuxent River, Maryland and one squadron, AEW Squadron Eleven (VW 11), permanently based at Naval Station Argentia, Newfoundland. Their mission was to fly orbits to the Azores and back. An additional AEW training unit was based at NAS Patuxent River for training flight crews and maintenance personnel. BARLANT became operational on 1 July 1956, and flew continuous coverage until early 1965. The barrier was shifted to cover the approaches between Greenland, Iceland, and the United Kingdom (GIUK) barrier in June 1961. Aircraft from Argentia were staged through NAS Keflavik, Iceland, to extend coverage times. The third air wing to operate EC 121s was 553rd Reconnaissance Wing, a Vietnam war organization activated in 1967 and based in Thailand until inactivation in 1970 (See BatCat below). In 1966, Lockheed modified 30 ex USN Super Constellations (two EC 121P/WV 3 and 28 EC 121K/WV 2) aircraft to EC 121Rs for the specialized reconnaissance mission flown by the 553rd. Aircraft were delivered during the course of 1967. The 553rd RW flew over land and off the coast of Vietnam, over Laos and Cambodia, monitoring and retransmitting low power signals. Usually, they orbited the Ho Chi Minh Trail in 8 hour shifts. As it was expensive to operate and it exposed a large crew to enemy fire, it was replaced in December 1970 by the much smaller (and eventually unmanned drone) QU 22 Pave Eagle sensor monitor. The EC 121s were designed for detection of aircraft flying over water, so ground clutter (spurious signal returns off of terrain features such as mountains) caused interference with their radar pictures. The crews, however, were experienced in tracking Soviet aircraft over Cuba and had developed a technique whereby an EC 121 flying at 50 feet (15 m) to 300 feet (91 m) above water could bounce a signal from its bottom mounted APS 95 Search radar off the surface of the water and detect aircraft at medium altitudes out to 150 mile (241 km). Operating in pairs, one Big Eye EC 121 flew a 50 mile (80 km) race track pattern approximately 30 mile (48 km) offshore (Alpha orbit), with the orbit's center at The second one flew a track at 10,000 feet (3048 m) (Bravo orbit) farther from the coast, acting as a spare for the Alpha EC 121. This provided a practical detection range of 100 mile (161 km), enough to cover the Hanoi urban area and the main MiG base at Phúc Yên. A major disadvantage of this arrangement, however, was that most MiG contacts were beyond the 70 mile (113 km) range of the Big Eye's APS 45 Height Finder radar, so that they were unable to provide this data to USAF strike forces. Furthermore, technical shortcomings in the EC 121D's systems precluded either controlling a fighter intercept or identifying a specific flight under attack. The missions from Tan Son Nhut AB began 21 April 1965, using callsigns Ethan Alpha and Ethan Bravo, which became standard. After refueling at Danang Air Base, Ethan Alpha made a wave top approach to its orbit station, where it remained for five hours. Because of the threat of MiG interception, EC 121s were protected by a Lockheed F 104 Starfighter MiGCAP. If, for any reason, the MiGCAP could not rendezvous, the EC 121s cancelled their mission. Air conditioning systems aboard the EC 121 were virtually useless in this profile, and the heat produced by the electronics, combined with the threat of being shot down, made Alpha orbit missions in particular very stressful. On 10 July 1965, in its first airborne controlled interception, an EC 121 provided warning to a pair of USAF F 4C fighters, resulting in the shooting down of two MiG 17s. Seven of 26 EC 121s deployed from Otis AFB and arrived at Korat, on the 19th. From April 1965 to early 1966 and beginning again in late 1967, the EC 121Ds also controlled a flight of MiGCAP fighters for unarmed support aircraft operating over the Tonkin Gulf. The EC 121Ds also served as an airborne communications relay center for strike aircraft to transmit mission results and position reports to Danang Air Control Center; directed operations of fighter escorts, MiGCAPs, Lockheed C 130 Hercules flare ships and A 26 strike aircraft along the North Vietnamese Laotian border; provided radar and navigational assistance for combat search and rescue missions; and assisted fighters in finding tankers for emergency refueling. In May 1966, the government of China formally protested an incursion by a Republic F 105 Thunderchief pursuing a North Vietnamese MiG it subsequently shot down 25 mile (40 km) inside Chinese territory. A US board of inquiry recommended that College Eye also had to monitor the "no fly zone" inside the North Vietnamese border with China, to provide alerts to US aircraft nearing the buffer zone and to report border crossing violations by US aircraft. In the last week of August, however, after a period of intensive training and revision of tactics, the MiGs began engaging US strike forces again, scoring a number of kills. Then, Seventh Air Force finally obtained permission for the new Ethan Bravo mission EC 121 to actively interrogate with QRC 248 on 6 October. By 4 December, its success outweighed any value in flying the Ethan Alpha orbit, which was discontinued until July 1972. On 1 March 1968, College Eye callsigns changed to Ethan 01, 02, 03 and 04. Ethan 03 (Laotian orbit) began "positive control" (airborne direction) of C 130 flareship flights and A 26 Invader night interdiction missions along the Ho Chi Minh Trail in Laos on 19 April 1968.

In August 1967, while the College Eye Task Force was still based at Udon RTAFB, another prototype EC 121 variation began operations testing new equipment as Detachment 2 of the Tactical Air Warfare Center. Known as Rivet Top, this modified EC 121K (later redesignated EC 121M) carried the QRC 248 newly installed in the College Eye aircraft and also had electronic interrogators capable of reading two additional Soviet transponders, the SRO 1 and SOD 57. Its electronics were custom built rather than off the shelf. Its most important upgrade was the top secret Rivet Gym installation. This consisted of the addition to the crew of Vietnamese speaking intelligence specialists manning four voice communications intercept stations able to monitor all communications between the MiGs and their GCI controllers. Despite this advantage, Rivet Top experienced two problems, reducing its effectiveness. Its operators did not have radar scopes to correlate intercepted conversations with specific flights of MiGs, thus could not determine which US aircraft might be under attack. Secondly, like QRC 248, Rivet Gym was an NSA SIGINT asset and subject to even more stringent rules protecting knowledge of its existence. Even when real time warnings to US aircraft were finally permitted in mid 1972, fighter crews were not made aware of the source of the warnings and because EC 121 radio communications were poor, mandating the use of a radio relay aircraft that often failed, they tended to disregard the credibility of the source. The Rivet Top prototype moved to Korat RTAFB along with the College Eye Task Force in October 1967. Originally scheduled to return to the USA in February 1968, because of its value, it remained at Korat until 1969. Flying daily missions through its testing period, it began flying every other day missions over the Gulf of Tonkin after 31 March 1968, when Rolling Thunder operations were sharply scaled back. Rivet Gym installations were back fitted to all College Eye EC 121s by the end of May 1968.

Two EC 121Ds, newly modified with the Southeast Asia Operational Requirement 62 (SEAOR 62) electronics suite, but not yet operational as EC 121Ts, were ordered to Korat RTAFB in October 1970. Under the guise of being field tested, they were accompanied by a C 121G carrying additional crew members, the most experienced 552nd AEWCW technicians, and equipment necessary to maintain the new electronics. The SEAOR 62 package was supported by a digital data receiver ground terminal and by radio relay equipment transshipped by separate classified airlift. The EC 121Ts arrived in Thailand from McClellan AFB on 12 November. The purpose of the deployment was to provide an integrated tactical data display with real time inputs (similar to the Navy Airborne Tactical Data System equipping E 1B Tracer platforms of Task Force 77) in support of Operation Kingpin, a mission to rescue US prisoners of war held at Son Tay prison. Once at Korat, some equipment was tested for the first time because of emission restrictions in US airspace and the only available manuals and checklists were notes from early flight tests. Even so, both aircraft were operational by 17 November. On 20 November 1970, two Warning Stars, using the callsigns Frog 01 and 02, respectively, took off 10 minutes apart at 22:00 from Korat to take station at the low altitude Alpha orbit over the Gulf of Tonkin, with Frog 02 as a backup. The 17 man crews were advised in the air of the nature of the rescue mission and their role, providing MiG warning and directing USAF F 4 Phantom CAP intercepts. As Frog 01 began its climb to the higher Bravo orbit, it experienced a ruptured oil line forcing shutdown of one engine. As planned, Frog 02 became the primary aircraft when Frog 01 made an emergency landing at Danang. The new equipment failed to function properly aboard Frog 02. The ground receivers at the command post in Danang failed to receive data and the APX 83 IFF processors would not display aboard the aircraft, despite repeated repairs. Their own radar monitors experienced excessive electronic noise and the jamming of North Vietnamese radars by nearby EKA 3B Skywarriors hindered efforts of the radar technicians to correct the problems. While unable to provide vectoring information to the F 4s escorting the mission, Frog 02 remained on station and relied on its Rivet Top voice intercept capability to provide supplementary data.

In October 1971, North Vietnamese MiGs, operating from forward bases opened after the end of Rolling Thunder, began a campaign to intercept Boeing B 52 Stratofortress missions over southern Laos. On 20 November, a MiG 21 launched air to air missiles at a B 52 that evaded by dropping flares. As a result, Warning Stars of Det. 1 returned to Korat RTAFB to provide radar support by flying the Laotian orbit again, using callsign Disco.|group=N although it continued to be handicapped by poor radio communications. In addition, its slow turning radar limited its value as a controller of fighters during MiG engagements, while the size of USAF raids during Linebacker nearly saturated its capabilities. Improvements made in the systems since 1968 enabled the operators to distinguish MiG types and a color code system for them entered the air operations vernacular: "Red Bandits" (Mig 17s); "White Bandits" (MiG 19s); "Blue Bandits" (MiG 21s), and "Black bandits" (MiGs low on fuel). On 6 July 1972, as the result of seven F 4 Phantoms shot down in a two week period, a second Disco track was initiated. Flown near the former Alpha orbit over the Gulf of Tonkin, its 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 communications 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.

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 which also killed four Thai civilians. 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 five 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 December 1970, with about 20 Batcats on hand at any time. The wing activated in December 1970 and the 554th RS relocated to Nakhon Phanom RTAFB to fly QU 22 sensor monitors nicknamed "Baby Bats". Initially with 11 aircraft, the 553rd RS continued operations for another year, gradually returning aircraft and crews to the USA. The final Batcat mission was in December 1971. The last remaining administrative and support personnel returned to Otis AFB in January 1972.

WV 1. 2 prototypes, L 749A Constellation, designated PO 1W before 1952
EC 121K (WV 2). Main USN variant, designated PO 2W before 1952; 244 ordered, 142 produced (the rest to USAF). JC 121K. One modified EC 121K used as a US Army avionics testbed
NC 121K. Unknown number modified as special mission aircraft
YEC 121K. One modified avionics testbed
EC 121L (WV 2E). One modified WV 2, testbed for rotating radar dome with an AN/APS 70 radar
EC 121M (WV 2Q). ELINT collection variant, 13 modified WV 2
WC 121N (WV 3. Weather reconnaissance variant, 8 modified WV 2
EC 121P. Unknown number modified from EC 121K as anti submarine variant
JEC 121P. 3 EC 121P used by the USAF