By David F Winkler,
for the United States Air Force Air Combat Command

June 1997

During President John F Kennedy's October 1962 confrontation with the Soviet Union over Soviet missiles in Cuba, the United States had military advantages. One advantage was the ability to defend against a possible bomber attack from the Soviet Union. Such an attack would have been detected early by a string of radar stations that stretched across northern Canada and Alaska. Once the intruding bombers crossed into North American airspace, their progress would have been monitored by an extensive system of long-range and short-range radar stations that dotted the landscape of the United States and Canada. These radar sites provided data to a system of combat and direction centers that formed the heart of what was called the Semi-Automatic Ground Environment (SAGE) system. From SAGE combat and direction centers, orders to engage the enemy bombers could be issued to the numerous interceptor squadrons, and to scores of Air Force BOMARC and Army Nike surface-to-air missile batteries scattered around the country.

However, the construction of this extensive air defense network to counter the Soviet threat had not been assured. During the late 1940s and 1950s, funding for radars, command and control centers, and interceptor aircraft and missiles often faced severe challenges from within the military, the Executive Branch, and in Congress.

Air defense concepts received little support because of a heavily institutionalized bias in the Army Air Forces that favored offense as the best defense. Prior to WW II air power advocates considered strategic bombing to be key to breaking enemy production capacity and civilian morale. The Army Air Forces pursued this doctrine with vigor over German and Japanese skies. During the Cold War, this philosophy was heralded by SAC. This chapter will trace the struggle of the proponents of defensive and offensive strategies before and during the early years of the Cold War.

Early Development of Air Defense

The Air Force based its offensive philosophy on experience, dating from World War 1, that repeatedly demonstrated that defensive forces were at a disadvantage against fast, high-flying bombers. To blunt German bomber attacks against their home island during 1918, the British established an elaborate system of barrage zones around London that included searchlights, observation posts, and antiaircraft artillery. Additional defensive measures included tethering large balloons on cables to thwart low-flying bombers and imposing blackouts on British cities to complicate targeting. However, only through the introduction of many fighter squadrons recalled from France were the British able to contain the German threat. After World War 1, air power advocates such as American General Billy Mitchell and Italian theorist Giulio Douchet argued that strategic bombardment would revolutionize warfare. In 1929, many Americans were impressed with the offensive advantage of the bombers in maneuvers over Ohio. There they observed that pursuit planes had difficulty approaching the faster and higher flying B-10. 1

Not everyone in the military was convinced of the impunity of bomber aircraft. During the 1930s, Captains Claire L Chennault and Gordon R Saville theorized that improved pursuit aircraft using defensive tactics could challenge the bomber claim to air supremacy. A breakthrough was achieved in 1935 when the Army experimented with a Ground Control Interception (GCI) system. A brainchild of Saville, the GCI system used high-frequency radios to vector interceptor aircraft towards incoming formations of bombers that had been spotted and reported by ground observers. Although the system could not stop a determined attack, it could hinder the attackers' destruction of the target and cost the enemy an unacceptable loss of bomber aircraft.

While the Army worked to improve the GCI system and pursuit aircraft, experiments initiated by the Naval Research Laboratory in Washington, DC, and the Army Signal Corps Laboratories at Fort Monmouth, New Jersey, proceeded to develop detection devices using radio waves. The Army also attempted to develop alternative detection devices targeting aircraft engine noise and heat signatures. However, aural and thermal detection devices had only limited potential because of the difficulty in detecting sound and heat at great distances. Fortunately, Army and Navy researchers progressed in their radio wave experiments. On December 14, 1936, the Army successfully tested a pulse radar at Princeton Junction, New Jersey. They were able to bounce radio waves off an aircraft out to a range of seven miles. A series of demonstrations conducted near Fort Monmouth, New Jersey, the following May proved even more promising and impressed Secretary of War, Harry A Woodring enough to increase research funding. Prototype radars tested in May 1937 were the direct predecessors of the Army SCR-268, SCR-270, and SCR-271 search radars. 2 Private research organizations such as Bell Telephone Laboratories joined the effort. The Navy also had success in developing radar units for deployment at sea. Tests during the late 1930s proved encouraging and the first production units joined the fleet in 1940. In an effort to name the new devices, the Navy invented the acronym RADAR for "Radio Detection And Ranging." 3 The Army also began to deploy radar sets. One unit, an SCR-27013, was operational on the morning of December 7, 1941, at Kahukii Point on Oahu, Hawaii. Unfortunately, the big sighting report called in to Pearl Harbor by the two assigned radarmen was ignored. 4

The Battle of Britain demonstrated the validity of Chennault and Saville's theory that improved pursuit aircraft challenge bomber supremacy. In coordinating the defense of their country, the British used a radar technology that they had been developing during the 1930s. Forewarned of a German bomber attack by primitive radar sets, ground control command posts efficiently deployed Royal Air Force Hurricane and Spitfire interceptor aircraft to wreak havoc on the attackers. Although the British defenders did not prevent the Nazi attackers from bombing their targets, they exacted enough in German aircraft losses to force Germany to reconsider its bombing strategy. 5

In 1940, as fighting continued over the skies of Britain, the Army established the ADC at Mitchel Field on Long Island, New York. Established to test systems and formulate doctrine, ADCs mission took on a sense of urgency after the Japanese attack at Pearl Harbor. By attacking the Hawaiian Islands with carrier-borne aircraft, the Japanese demonstrated that the American west coast was also vulnerable to carrier aircraft. In the wake of the attack, ADC scrambled to deploy interceptor squadrons, radar sets, and gun emplacements. Ninety-five radar stations were eventually set up along the east and west coasts using SCR-270 (mobile) and SCR-271 (fixed) radar sets. These radars had an optimum range of 150 miles distance at 20,000 feet elevation. Thousands of civilian volunteers joined Ground Observer Corps to scan the skies up and down the east and west coasts for enemy aircraft. 6

In addition to an air defense infrastructure, a scientific and industrial infrastructure also was developed. At the Massachusetts Institute of Technology (MIT), a cadre of scientists and engineers worked at what was called the "Radiation Laboratory" to develop and test new radar systems. During the war, the Radiation Laboratory produced some 150 distinct military radar systems that had land, sea, and air applications. Because of its contribution to the war effort, MIT was positioned to contribute solutions to America's air defense problems in the post-war era. 7

Radars designed by MIT were not needed on the home front during World War II. American victory at Midway Island and an allied invasion into North Africa calmed public concerns about enemy bombings. By 1943, air defense on the home front had become a low priority. As a result, the ADC was disestablished.

Although domestic air defenses were never tested during the war, the Battle of Britain, coupled with Army Air Forces difficulties in penetrating German airspace, demonstrated that effective air defense could prove potent. However, the dropping of atomic bombs on Hiroshima and Nagasaki also restored confidence in the doctrine of offensive operations. At the conclusion of the war, all air defenses were shut down. 8

The Post-War Era

During World War II, consideration had been given to how America's air defense system would operate during the post-war era. Subsequently, the Army Air Forces received responsibility for manning, training, equipping, and deploying the fighter forces and needed warning radar stations. To organize its resources, the Army Air Forces reorganized. to form the SAC, the TAC, and the reestablished ADC. 9

Activated on March 27, 1946, the new ADC was directed to "organize and administer the integrated air defense system of the Continental United States." 10 With virtually no radars in operation and its fighter aircraft relegated to National Guard units, ADCs initial emphasis was on planning. Headquartered at Mitchel Field, New York, the new organization came under the command of Lieutenant General George E Stratemeyer.

For air defense planners, the late 1940s proved a challenging period. Although the Cold War was becoming a reality, national leaders did not acknowledge the Soviet Union as an immediate military threat to the North American continent. American intelligence was aware that the Soviets were producing their own version of the American B-29 bomber; however, reconnaissance efforts in the late 1940s indicated that the Soviets were not constructing bomber bases in areas that could bring these planes within striking distance of the continental United States. Furthermore, the United States still retained sole possession of the atomic bomb. Air power projection advocates such as General Carl A Spaatz and General Curtis LeMay viewed delivery of the atomic bomb as the primary Army Air Forces mission. They emphasized offensive air power as the best method of defense. Ground rules were set and would remain intact for years to come. Thus air defense planners competed against fellow Army Air Forces officers in the struggle to obtain appropriations.

For the ADC, the appropriations battle was a difficult struggle. In the immediate post-war era severe budget cuts rocked the entire military establishment. With reduced resources, Army Air Forces' Chief of Staff General Carl Spaatz provided support to SAC and TAC at the expense of ADC. Lieutenant General Earle E Partridge, the Assistant Air Chief of Staff for Operations, felt that it would be a mistake for the Army Air Forces to give the public an impression, less than a year after Japan's surrender, that an air' attack was anticipated. Instead, Partridge argued that funds should be used for research and development of longer-range radars. 11

With the Soviet Union posing a potential threat, in 1946 Douglas Aircraft Company's Research and Development (RAND) Project (later to become known as the RAND Corporation) was asked by the Army Air Forces to appraise the air defense problem. While the RAND Project conducted its study, the Army Air Forces directed the ADC to draft a proposal to employ existing equipment. In October and November 1946, Lt. General Stratemeyer submitted two proposals. The October proposal was a short-term plan that concentrated air defense forces in the northeast and northwest. The November proposal was a longer-term plan, calling for the use of twenty-four radars to be installed by 1949 to guard the approaches to five strategic areas that encompassed the northeast, the Chicago-Detroit area, and the three west coast cities of Seattle, San Francisco, and Leangles. However, in testimony before the House Appropriations Committee on March 6,1947, General Spaatz suggested that the best defensive strategy was to attack the enemy bombers at their home airfields. With a defense reorganization pending that promised the creation of an independent United States Air Force, Spaatz advised the ADC commander, Lt. General Stratemeyer, not to press demands. Still, planning continued and in April 1947, ADC proposed a network of 114 radars. 12

In July 1947, the RAND Project issued a preliminary report recommending against earlier proposals that had called for immediate deployment of a radar net using World War II vintage equipment. Because an enemy air attack was considered highly improbable, the RAND Project recommended a minimal air defense. The military reorganization prompted by the National Security Act of 1947 froze any consideration for radar deployment during mid-1947 as the services settled down to redefine their missions. Finally, on November 12, 1947, Secretary of Defense James V Forrestal announced that planning was underway for a national early warning radar network. Nine days later, General Spaatz; approved the blueprint calling for a radar fence plan of 374 radar stations and 14 control centers to be built throughout the continental United States and an additional 37 stations and 4 control centers to be placed in Alaska. Called Project SUPREMACY, the plan predicted that with immediate funding, the system would be operational by mid-1953. Under this scheme, the radar stations would report intruding aircraft to the regional control center that in turn alerted interceptor aircraft. Once the interceptor aircraft were airborne, the radar stations would assume control and vector the interceptors against the attackers. 13

The proposed Project SUPREMACY represented an enormous leap from what existed at the end of 1947. At that time ADC operated only two radar stations: one at Arlington, Washington, and one at Half Moon Bay near San Francisco, California. Manned by the 505th Aircraft Control and Warning (AC&W) Group, these stations worked with fighter squadrons to perfect ground-control and interception techniques. The experience gained from operating these two sites proved invaluable to air defense planners who were designing the nationwide system. 14

As Project SUPREMACY was undergoing consideration, relations with the Soviet Union continued to sour. In February 1948, there was a Communist coup in Czechoslovakia. In China, Communist forces continued to gain ground against Chiang Kai-shek. Air Force intelligence warned that the Soviets were preparing to conduct a surprise attack. On March 27, 1948, General Spaatz, concerned about the vulnerability of the Atomic Energy Commission plant at Hanford, Washington, ordered the recently placed ADC radars at Arlington, Spokane, Neah Bay, and Hanford, Washington, and at Portland, Oregon, to begin operating on a 24 hour-a-day basis. Due to insufficient personnel and materiel resources, round-the-clock operations in the northwest proved beyond ADCs capability. Despite these problems, ADC was ordered to take AN/CPS-5 and AN/TPS-1B/1D radar sets out of storage for operation in the northeast and in Albuquerque, New Mexico. By August, radars had been placed at Twin Lights and Palermo in New Jersey, and at Montauk, New York. In September 1948, the Air Force ordered thirteen additional World War II radars to be placed in operation over an area stretching from Maine to Michigan. Along with the previously sited radars, these sets became incorporated into what became known as the Lashup system. Lashup was an appropriate name for the sys-tem as World War II vintage radar antennas were literally lashed to the top of wooden platforms. In addition to the temporary antenna towers, Quonset huts and short-term wooden structures were built to house the equipment and radar operators. 15

Despite further deterioration in the relationship between the United States and the Soviet Union, and the imminent fall of China, the price for Project SUPREMACY was still considered too costly by Defense Secretary Forrestal. The Project SUPREMACY plan ultimately was never implemented. To address the Secretary's financial concerns and still move ahead to deploy a radar network, in mid-1948 Air Force Vice Chief of Staff Muir S Fairchild appointed air defense expert Major General Gordon R Saville to a position as ADC Headquarters Special Projects Officer. After nearly two months, the team that Saville brought together produced a new plan that argued for deployment of a radar network as the first step in developing a credible air defense system.

Saville proposed a system of seventy-five radar stations and ten control stations in the continental United States and ten radar stations and a control center for Alaska. To Saville, this plan represented starting point. The seventy-five-station system eventually was dubbed the "permanent network." Additional stations could be built later to provide the coverage envisioned under Project SUPREMACY.

The plan found an advocate in Colonel Charles Lindbergh. Having been placed on active duty as a special consultant to evaluate technical and operational matters, Lindbergh argued that SAC bombers needed to fly against actual radar networks to provide a realistic assessment of their power projection capability. Thus a radar network would serve not only to detect intruders, but also to provide SAC a test bed to develop tactics to avoid detection. In October 1948, Forrestal approved Saville's plan. 16

Forrestal's approval came at time when President Harry S Truman sought further cuts in the defense budget. The Air Force adjusted to the cuts by maintaining support for SAC and consolidating TAC and ADC into the Continental Air Command (CONAC). Formed on December 1, 1948, the new organization was headed by General Straterneyer. Now a component command of CONAC, ADC was commanded by Major General Saville. 17

Reflecting the President's interest in fiscal austerity, Louis Johnson, Forrestal's replacement as Secretary of Defense, kept the request for radar funding out of the supplemental 1949 and Fiscal Year (FY) 1950 budgets. Events in late 1949 began to arouse public concern over air defense. In August, under the encouragement of the Air Force, Boeing Company announced plans to shift B-47 production from Seattle to the less-vulnerable Wichita, Kansas. This announcement drew protest from Seattle leaders as well as Alaska's governor. It was their opinion that the Boeing move represented a tacit admission by the Air Force of the vulnerability of Alaska and the northwest to Soviet attack. During hearings before the House Armed Services Committee on the B-36 program, Navy leaders also questioned the Air Force's lack of expenditures on air defense. Finally, with President Truman's announcement on September 22, 1949, of a recent Soviet detonation of an atomic bomb, public interest in air defense became rampant. Money was made available in the FY 1950 budget to start air defense construction. In addition, Congress granted the Air Force authority to transfer money from other projects to expedite building the permanent network. 18

On December 2, 1949, the Air Force directed the Army Corps of Engineers to proceed with construction of the first twenty-four radar sites on Saville's seventy-five-site list. Areas covered by these sites included northeastern, midwestern, and western metropolitan regions, and Atomic Energy Commission sites in Washington and New Mexico. Many of these locations already had temporary radars operating as part of the Lashup system. By mid-1950, forty-four Lashup installations already were operating around the strategically important areas. Once the permanent network stations became operational, the Lashup stations would be retired. 19

Also in 1950, other steps were taken to improve the nation's air warning capabilities. The Ground Observer Corps (GOC) was reestablished. In addition, Canada and the United States agreed to extend the American radar network into Canada. To complete this effort, the United States cooperated in constructing, equipping, and operating some of these stations on the northern side of the US-Canadian border as well as those on the southern side. This string of stations straddling the border became known as the "Pinetree Line." 20

By the late 1950s, deployment of the short-range AN/FPS-14 radar resolved the problem of detecting low-flying planes. Dozens of AN/FPS-14s and the follow-on model AN/FPS-18s were deployed at sites between the long-range permanent and mobile radar stations. As a result of this technological improvement, the GOC was deactivated on January 31, 1959.

Building the Network

On June 25, 1950, North Korea launched an invasion of South Korea, drawing the United States into a war that would last for three years. Believing that the North Korean attack could represent the first phase of a Soviet-inspired general war, the Joint Chiefs of Staff ordered Air Force air defense forces to a special alert status. In the process of placing forces on heightened alert, the Air Force uncovered major weaknesses in the coordination of defensive units to defend the nation's airspace. As a result, an air defense command and control structure began to develop and Air Defense Identification Zones(ADIZ) were staked out along the nation's frontiers. With the establishment of ADIZ, unidentified aircraft approaching North American airspace would be interrogated by radio. If the radio interrogation failed to identify the aircraft, the Air Force launched interceptor aircraft to identify the intruder visually. In addition, the Air Force received Army cooperation. The commander of the Army's Antiaircraft Artillery Command allowed the Air Force to take operational control of the gun batteries as part of a coordinated defense in the event of attack. 21

On July 11, 1950, the Secretary of the Air Force requested approval from the Secretary of Defense to expedite construction of the second segment of twenty-eight stations for the permanent network. Most of these stations provided additional coverage to eastern, mid-western, and western regions of the country. Receiving the Defense Secretary's approval on July 21, the Air Force directed the Corps of Engineers to proceed with construction.

The remaining twenty-three permanent network sites were approved for construction later in 1950. Located primarily in Minnesota, North Dakota, and Montana, these sites formed the American component of the Pinetree Line. In September 1950, Congress pro-vided a supplemental appropriation of $40 million to fund construction and equip the sites with the newest radars. 22

Before a closed session of the House Armed Services Committee on July 27, 1950, Continental Air Command Vice Commander General Charles T Myers pledged that the seventy-five stations would be finished by July 1, 1951. This promise proved impossible to keep. Lack of coordination between various Air Force commands and the Army Corps of Engineers, funding problems, manpower shortages, building material and spare part shortages, as well as a strike at General Electric's radar fabrication plant all slowed progress. By the end of December 1950, the completion date for the permanent network had been set back six months. 23

As construction of the permanent network proceeded, Congressional concerns about air defense prompted a reorganization of the Air Force. On January 1, 1951, the Air Force reestablished ADC as a major command to be headquartered at Ent Air Force Base (AFB) in Colorado.

In the wake of Communist China's intervention in Korea, Congress approved President Truman's request for supplemental funds that included appropriations for a mobile radar network to supplement the permanent network. 24 In July 1951, ADC received approval to install forty-four mobile radars to provide protection for key SAC bases. ADC planned to have these radars operating the following July. The permanent sites were designated P-sites and the mobile sites were designated M-sites. In January 1952, ADC decided to position some of the mobile radars in conjunction with permanent sites to form a double perimeter that these mobile sites would remain in the same location for the long term, ADC directed the Army Corps of Engineers to build permanent support facilities at each site. As with the permanent network, mobile radar deployment was slowed due to procurement problems. 25

As nearly all stations of the permanent network reached operational status, the Air Force approved the second phase of the mobile radar program on October 18, 1952. These stations were designated as second mobile or SM-sites. (One example was the unit located at Kamloops, BC, in Canada which was designated as SM-153). Meanwhile, the Navy was asked to provide radar picket ships to cover coastal approaches and the Air Force began to purchase EC-121 Lockheed Constellation planes to provide additional radar coverage. 26

The Debate

Even with a fully capable radar system serving as the foundation of an air defense infrastructure, the Air Force claimed the United States could stop only thirty percent of an attack, at best. However, in 1950, Dr. George E Valley, Jr., an MIT physics professor and member of the US Air Force Scientific Advisory board, led a committee that more realistically concluded that the air defense system could stop only about ten percent of an attack. The Valley Committee recommended solutions that included establishing an air defense laboratory at MIT. This laboratory would employ new technologies to improve this percentage rate. The Air Force expressed interest in establishing such a laboratory. However, resistance existed at MIT by faculty who objected to the university's continuing support of military research and development. MIT President James R Killian convened a study group, named "Project CHARLES," to examine the laboratory proposal. In addition to agreeing that MIT should host an air defense laboratory, Project CHARLES concluded that technology existed that was capable of surmounting the air defense problem. By establishing a laboratory dedicated to air defense, MIT took on a project with a budget twice that of its undergraduate teaching program. The air defense laboratory at MIT eventually became known as the Lincoln Laboratory. 27

In partnership with the Air Force, Cambridge Research Laboratory, and IBM, the Lincoln Laboratory immediately began work to modify a Whirlwind computer that was being developed for the Navy's use in performing air defense command and control functions. What emerged was the AN/FSQ-7, otherwise known as Whirlwind II. In 1951, Whirlwind II was first tested by placing the computer at a control center in Cambridge to receive data from a long-range and several short-range radars set up on Cape Cod. Tests proved promising, but years of development still lay ahead. The key breakthrough was the development of magnetic-core memory that vastly improved the computer's reliability. When the previous electrostatic-storage-tube memory was replaced by magnetic-core memory, operating speed doubled and input speed quadrupled. More significantly, maintenance time for the core memory dropped from four hours per day to two hours per week. 28

On April 16, 1952, after receiving reports from Alaska and Maine of unidentified incoming aircraft, ADC Headquarters issued an air defense readiness alert that caused hundreds of pilots to scramble to their planes and gun crews to man their antiaircraft guns. The threat was later determined to be false. Air defense planners were forced to acknowledge limited capability to evaluate threats and respond. Telephone and teletype communications were too slow to keep an air defense commander cognizant of an evolving air battle. In the wake of the false alert, defense planners decided to reevaluate the emerging air defense system. 29

A "Summer Study Group" met from June through August 1952 at MIT. Twenty scientists and engineers, along with several consultants, considered current and future threats, such as Intercontinental Ballistic Missiles (ICBMs), to the United States. Regarding the current threat, the group concluded that early warning was critical for a successful defense. They recommended the establishment of a Distant Early Warning (DEW) Line across the northern tier of the North American continent. They further concluded that automation of command and control through the introduction of computers, such as Whirlwind II, would give air defense commanders valuable minutes to properly deploy interceptor aircraft. 30

Throughout late 1952, Air Force officials and scientists vigorously debated the DEW Line proposal. Opponents feared that the United States would build a Maginot Line at the expense of SAC. The debate was internal. Neither Congress nor the American people were aware of the proposals being discussed. At the end of 1952, President Truman stepped in and signed the National Security Council (NSC) directive 139. NSC 139 directed the construction of the DEW Line. After reevaluating Soviet atomic bomb and bomber production rates, NSC 139 preparers identified 1955 as a period of maximum danger. Facing this imminent Soviet threat, defense planners considered an effective air defense warning system to be essential. 31

However, newly elected President Dwight D Eisenhower desired a reduction in defense spending and a change of priorities. The new administration no longer considered 1955 to be a period of maximum danger. Air defense again was scrutinized by a committee headed by Bell Telephone Laboratories president Mervin J Kelly. While the Kelly Committee reviewed Summer Study Group recommendations, the American people became aware of the debate through congressional testimony and press coverage. On March 6, 1953, Air Force Chief of Staff General Hoyt S Vandenberg testified before Congress against funding for defensive systems at the expense of improving American air offensive capabilities. Newspaper columnists Joseph and Stewart Alsop strongly disagreed. In their New York Herald Tribune columns, the Alsop brothers published accounts of the Summer Study Group recommendations and the subsequent deliberations portraying the Air Force, and specifically SAC, as villains suppressing technological advances. In May 1953, the Kelly Committee issued a report that seemed to vindicate both sides; both sides interpreted the report in their favor.

Not pleased with the Kelly Committee findings, Defense Secretary Charles E Wilson appointed retired Army Lieutenant General Harold R Bull to lead another committee. In July 1953, the Bull Committee submitted a report that supported many of the Air Force planning efforts. The report recommended construction of a sensor line across mid-Canada as a top priority. Second priority would go to building the DEW Line (if experimental tests in Alaska proved it workable); deploying an automated command and control system; building an unmanned network of short-range, low-altitude, gap-filler radars to replace the Ground Observer Corps; and implementing an improved aircraft identification system. Due to questioning by the Joint Chiefs regarding the priorities of the Bull Report, the National Security Council postponed consideration of the findings until September 1, 1953. In the wake of the Soviet explosion of a hydrogen bomb in August 1953, the National Security Council approved an amended version of the Bull report. The approval document, NSC 159/4, proved significant; the Air Force received support to proceed with the development of an air defense structure. 32

Thus the path was cleared for the ADC to request funding for a third phase of mobile radars that would prevent and end-run around the northern-oriented detection belt. These radars, to be placed along the east and west coasts and in the south, were called third mobile or TM-sites. The Air Force approved this request and budgeted for the integration of an automated command and control system into the air defense network. 33 This system was being developed at Lincoln Laboratory.

The emphasis on defense approved in NSC 159/4 seemed to contrast with the policy promulgated in late 1953 in NSC 162, a policy that became known as the "New Look." The New Look had an emphasis on massive retaliation. Yet, the two policies were complementary. Eisenhower recognized that if America was to deter war through massive retaliation, it needed air defenses to ensure the survival of its retaliation force. Thus strong air defense contributed to the credibility of the American strategy. 34

Planning went ahead for a future defensive structure. However, execution of current plans lagged due to construction and equipment procurement problems. As of late 1953, not one mobile radar station was operational and sites were still being surveyed for the second phase of mobile radars. 35

Improving Command and Control

The permanent network depended on each radar site to perform GCI functions or pass information to a nearby GCI center. For example, information gathered by North Truro Air Force Station on Cape Cod was transmitted via three dedicated land lines to the GCI center at Otis AFB, Massachusetts, and then on to the ADC Headquarters at Ent AFB, Colorado.

The facility at Otis AFB was a regional information clearinghouse that integrated the data from North Truro and other regional radar stations, Navy picket ships, and the volunteer GOC. The clearinghouse operation was labor intensive. The data had to be manually copied onto Plexiglas plotting boards. The ground controllers used this data to direct defensive fighters to their targets. It was a slow and cumbersome process, fraught with difficulties. Engagement information was passed on to command headquarters by telephone and teletype.

At Ent AFB, the information received from the regional clearinghouse was then passed on to enlisted airmen standing on scaffolds behind the world's largest Plexiglas board. Using grease pencils, these airmen etched the progress of enemy bombers onto the back of the Plexiglas board so that air defense commanders could evaluate and respond. This arrangement impeded rapid response to the air battle. 36

At the Lincoln Laboratory development continued on an automated command and control system centered around the 250-ton Whirlwind II (AN/FSQ-7) computer. Containing some 49,000 vacuum tubes, the Whirlwind II became a central component of the SAGE system. SAGE, a system of analog computer-equipped direction centers, processed information from ground radars, picket ships, early-warning aircraft, and ground observers onto a generated radarscope to create a composite picture of the emerging air battle. Gone were the Plexiglas boards and teletype reports. Having an instantaneous view of the air picture over North America, defense commanders would be able to quickly evaluate the threats and effectively deploy interceptors and missiles to meet the threat.

By 1954, with several more radars in the northeast providing data, the Cambridge control center (a prototype SAGE center) gained experience in directing F-86D interceptors against B-47 bombers performing mock raids. Still much development, research, and testing lay ahead. Bringing together long-range radar, communications, microwave electronics, and digital computer technologies required the largest research and development effort since the Manhattan Project. During its first ten years, the government spent $8 billion to develop and deploy SAGE. By 1958, Lincoln Laboratory had a professional staff of 720 with an annual budget of $22.5 million, to conduct SAGE-related work. The contract with IBM to build sixty production models of the Whirlwind II at $30 million each provided about half of the corporation's revenues for the 1950s and exposed the corporation to technologies that it would use in the 1960s to dominate the computer industry. In the meantime, scientists and electronic engineers in the defense industry strove to install better radars and make these radars invulnerable to electronic countermeasures (ECM), commonly called jamming. 37

Improving the Radar Network

In addition to SAGE center development, Progress continued on mobile and other radar network installations. On December 6, 1954, Site M-129 at MacDill AFB, Florida, became the first mobile radar site to achieve operational status.

By the end of 1955, thirteen Phase I mobile (M-site) and one Phase II second mobile (SM-site) stations were operational. They joined seventy-five stations of the permanent network. Along with these stations, other radar lines were constructed in Canada. The Pinetree Line, operational in 1954, straddled the United States/Canadian border and consisted of over thirty stations. The United States paid two-thirds of the costs and pro-vided most of the manpower. North of the Pinetree Line was the Mid-Canada Line, built by the Canadian government. The Mid-Canada Line consisted of an unmanned microwave fence designed to detect flyovers.

The DEW Line began with an experimental station at Barter Island, Alaska, in early 1953. During the summer, work began on an eighteen-site test line across northern Alaska and northwestern Canada. By 1954, successful tests at these stations spurred extending the line across the Canadian arctic. By the end of 1957, fifty-seven stations were completed in a very costly and challenging construction effort. 38

As the radar network expanded to the top of the North American continent, defensive planners expressed concern that the radars in operation would not be capable of detecting new high-altitude aircraft. The AN/FPS-3, a radar designed and built after World War II, could detect targets only up to 55,000 feet. In the early 1950s, technicians combined a device featuring a klystron tube with the radar to improve height-detection capability. With this device, called the GPA-27, the redesignated AN/FPS-3A radar could detect targets at 65,000 feet. Beginning in 1956, GPA-27 kits were installed at AN/FPS-3 sites. In addition to the older radars retrofitted with the GPA-27, new sets received the device as integral equipment. Designated as the AN/FPS-20, these new radars began to perform air search duties in 1957 and continued in service through the end of the Cold War. 39

Another post-World War Il radar, the AN/CPS-6, also faced obsolescence. Rather than invest much money to slightly improve the sets' performance, the Air Force decided to replace them with the AN/FPS-7 that was being developed for the Navy by General Electric (GE). The AN/FPS-7 held promise for detecting targets up to 100,000 feet. In 1955, ADC received authorization to acquire thirty-three of these sets. Development problems delayed deployment. The first set began operating at Highlands, New Jersey, in 1959. 40

In 1955, an inter-service study group named "Project LAMPLIGHT" reported that ECM could easily blind the current radar system. The study's conclusions were confirmed a year later when SAC bombers with ECM equipment blinded the ADC radar network during a mock attack. The Air Research and Development Command accepted the LAMPLIGHT Report and began developing a frequency-diversity (FD) radar. By giving the radar operator the ability to change the frequency of the radio wave emitted from the radar antenna, scientists and electrical engineers believed they could counter enemy testing lay jamming attempts. As with SAGE, years of research, development, and ahead. 41

During the late 1950s another area of progress was the development and deployment of AN/FPS-14 and AN/FPS-18 gap-filler radars. (There were six USAF manned Gap Filler sites that operated as part of the Pinetree Line in Canada). Having a range of around sixty-five miles, these radars were placed in areas where it was thought enemy aircraft could fly low to avoid detection by the longer-range radars of the permanent and mobile radar networks. Gap-filler radar deployment peaked in December 1960 at 131 sites throughout the continental United States. Because the introduction of gap-filler radars alleviated the need for civilians to scan the skies for enemy bombers, the ADC disestablished the Ground Observer Corps on January 31, 1959. 42

In August 1957, the Soviets successfully launched the SS-6 Sapwood ICBM. With an estimated range of 6,000 miles, the SS-6 represented a quantum leap in the Soviet rocketry program. American leaders were concerned as the Soviets now potentially had the capability to circumvent the North American air defenses. This concern was increased on October 4, 1957, when the Soviet Union launched Sputnik. With the advent of Sputnik, the general public became aware of America's potential vulnerability and placed US defense programs in the spotlight. 43

With this new threat on the horizon, work continued to improve the nation's ability to defend against a bomber attack. The first SAGE center became operational at McGuire AFB, New Jersey in June 1958. Air defenses reached a zenith in 1962. Although there were fewer combat and direction centers than originally planned, the air defense system conceived in the early 1950s was largely in place. By 1962 the SAGE system was completed. From the permanent and mobile radar construction programs, 142 primary radar stations and 96 gap-filler radar sites were operational in the United States and Canada providing data to the SAGE centers. Many of the primary radar stations hosted FD radars. The DEW Line across the northern continent was complete.

The SAGE combat and direction centers commanded a vast array of weapon systems. Forty-one interceptor squadrons numbering 800 aircraft, seven BOMARC missile squadrons (two of which were located in Canada), and scores of Amy Nike missile battalions stood ready. 44

In retrospect, it is easy to understand reasons for the decline of America's air defenses in the years following 1962. Technical advances threatened to make America's air defenses irrelevant. Speaking before the House Subcommittee on Department of Defense Appropriations in February 1966, Defense Secretary Robert McNamara stated:

The introduction of ICBMs gave defensive planners a challenge they could not overcome, even though the Army spent billions of dollars to field an Antiballistic Missile (ABM) system. Despite the Army program, Secretary McNamara felt that an attack could only be deterred through the assured destruction of any attacker. Consequently, billions of dollars were spent to upgrade strategic forces; SAC sunk 1,000 Minuteman silos into the western countryside and the Navy commissioned forty-one ballistic missile submarines. The Soviets countered with their own deployment of extensive rocket forces and missile-equipped submarines. Warning networks were upgraded only to allow strategic forces additional time to launch a retaliatory blow should the Soviets launch an attack. For the time being, the proponents of offense as the best defense had won their case. 46

The Radar Network After Sputnik

The new missile threat did not remove the bomber threat. However, many in Congress felt that funds spent on bomber defenses were wasted. During 1959, funds for additional FD and gap-filler radars were cut. Cuts were also made to the SAGE command and control program. 47

The funding prospects for air defense planners continued to look gloomy in 1960 as the Air Force advised NORAD that funding cuts expected in FY 1961 would force a revision of plans. Subsequently, NORAD identified twenty-six stations that could be released from the radar network. Some of the sites could be transferred to the FAA. The Air Force approved the plan and the deletions were made. 48

Meanwhile, funding cuts and technical difficulties plagued the frequency-diversity radar program. Testing of the AN/FPS-24, AN/FPS-27, and AN/FPS-35 revealed serious design deficiencies. Technicians worried that the FD radars might not be compatible with the new SAGE system. Concerns were expressed that the high-power output would interfere with other electronic systems. These concerns were confirmed when passing radar beams of an AN/FPS-35 being tested at Montauk, Long Island, interfered with radio receivers and scrambled television signals over a six-mile radius. At Almaden, California, testing of an AN/FPS-24 radar could only be conducted at times when the local television stations were not broadcasting. As more FD radars began testing, complaints from television and radio station owners, as well as viewers and listeners, began to mount in Congress. To review the problem, the Air Force called for a two-day conference at Hanscom Field, Massachusetts, at the beginning of August 1962. After reviewing the problem, electronics experts concluded that the interference problems could be resolved if broadcasters followed a few simple procedures. Consequently, the path was opened for round-the-clock FD radar operations. 49

While the ADC struggled to field FD radars, improvements to the existing network of AN/FPS-20 radars made it less susceptible to jamming. With the installation of Bendix-produced AN/GPA-102 or AN/GPA-103 kits, the performance of the radars improved to such a degree that they warranted redesignation. By the end of 1962, over one-third of the 131 primary radars within the air defense network were FD types or were electronic counter-countermeasure (ECCM)-modified AN/FPS-20s. Fifty radars were AN/FPS-7 sets that also had an ECCM capability. 50

With few exceptions, by the end of 1962 air defense network radars provided data feeds into the completed SAGE command and control network. A national network, SAGE included eight regional combat centers and twenty-two direction centers scattered around the nation. SAGE designers built redundancy into the system, which gave each combat center the capability to coordinate defense for the whole nation. Meanwhile, direction centers evaluated data feeds from sector radar sites and directed aircraft and missiles against the threat. The final SAGE direction center became operational at Sioux City, Iowa, in December 1961. SAGE centers allowed for a dramatic reduction of man-power over individual radar stations that once handled GCI functions. Manning levels dropped from nearly 200 to just over 100 men. Units designated as Aircraft Control and Warning Squadrons were renamed as Radar Squadrons (SAGE).

SAGE was a powerful, albeit expensive system. It was also extraordinarily vulnerable. The combat and direction centers were housed in huge concrete blockhouses, hardened to withstand overpressures of only five pounds per square inch. The advent of Sputnik affected the planning and deployment of the command and control system. Air Force planners realized that Soviet ICBMs could destroy all or part of the SAGE system long before the first of their bombers crossed the Arctic Circle.

Fortunately, the technological achievement of the Soviet SS-6 Sapwood ICBM and Sputnik was matched by an American technological breakthrough of perhaps much greater significance. In the spring of 1958, IBM announced the development of a solid-state computer. Substituting transistors for vacuum tubes, air defense computers could be reduced in size and placed underground in hardened, reinforced concrete facilities. However, ADC plans to construct hardened facilities for SAGE centers were never fulfilled; spending priorities were shifted to develop and deploy American ICBMs. 52

In March 1961, President John F Kennedy indicated in his budget message support for a manual back-up system to augment SAGE centers. Speaking before the House Armed Services Committee in April 1961, Secretary of Defense McNamara envisioned adding manual, ground-control intercept capability to augment SAGE centers at radar stations located away from probable target areas. 53

By the summer of 1961, NORAD was developing plans for what would become known as the Backup Interceptor Control (BUIC) system. Originally, the plan provided for an automated command and control capability for seventy radar stations. Eventually, the list was reduced to thirty in the United States and four in Canada. Some of these sites were planned as master control centers while others were planned as associate centers. Master control centers would assume immediate control of a sector should the regional SAGE direction center be knocked out. Associate centers provided additional redundancy. Site selection criteria focused on vulnerability. A station had to be located at least fifteen miles from an anticipated target. ADC favored locations with good radar coverage along with proximity to interceptor bases. To pay for the program, funds were transferred from the SAGE and FD radar programs.

BUIC implementation was envisioned as a two-phase plan. BUIC I consisted of the manual backup system originally proposed by McNamara. Twenty-seven radar sites were selected as master or NORAD control centers. Twenty-eight radars acted as associate centers with Ground Control Interception capability. Placing the system in operation simply meant restoring billets that were lost when GCI functions were assumed by the SAGE system. BUIC I reached initial operating capability in December 1962. 54

At the mine time BUIC I was becoming operational, contractors were submitting bids to provide the 'brains" for the follow-on automated BUIC II system. BUIC II radar sites would be capable of incorporating data feeds from other radar sectors directly onto their radar screens. In mid-1962, Burroughs Corporation won the contract to provide a military version of its D825 computer to be called the Radar Course Directing Group, AN/GSA-51. 55

Another back-up command and control program also had its roots during this time, The Airborne Surveillance and Control System (ASACS) was conceived by ADC planners to perform the role of a flying BUIC. Two phases of aircraft were planned with the more sophisticated version to become available in 1970. 56

Meanwhile, the SAGE system and the primary radar system faced further budget cuts. On December 3, 1962, McNamara recommended closing six SAGE direction command and control centers and seventeen radar stations by mid-1964; President Kennedy approved the measure.

The projected closure of SAGE direction centers sent air defense planners scrambling to prioritize the placement of the thirty-four proposed BUIC II sites. On June 4,1963, the Air Force approved installation of BUIC II at the first seven sites on the priority list. 57

During the BUIC II site selection process, at Secretary McNamara's direction, the Air Force undertook a detailed study to examine air defense requirements through 1975. In response, a Continental Air Defense Study (CADS) was completed in May 1963 that called for the replacement of SAGE centers by an improved BUIC and an Airborne Warning and Control System (AWACS) sometime between 1966 and 1975. The improved BUIC sites (BUIC III) foresaw an upgraded AN/GSA-51 capable of integrating surveillance data from ten radar and providing an expanded control capability. The CADS recommended forty-six stations be given this capability. The DoD placed the recommendations on hold to await evaluations on the capabilities of airborne radar operating over land. Eventually, DoD determined that AWACS would not be ready for deployment until after 1970. 58 Work proceeded on the installation of BUIC II and development of BUIC III. In 1966, after the installation of a Burroughs CSA-51 computer system, North Trum Air Force Station (AFS) on Cape Cod became the first ADC installation configured as a BUIC II site. In 1968, North Truro also became the first radar station to be designated a BUIC III installation. 59

In addition to establishing BUIC sites, extraordinary steps were taken to protect the defense system's control center. Because of the vulnerability of Ent AFB to nuclear attack, planning had begun in 1956 for a more secure command post elsewhere. Former NORAD Commanding General Earle E Partridge once observed that the two-story NORAD command building at Ent could be immobilized by a well-aimed bazooka shot, much less by a nuclear blast. To address the problem, architects designed a secure center to be set within man-made caverns in Cheyenne Mountain south of Colorado Springs, Colorado. The Corps of Engineers Omaha District oversaw the massive effort to dig out the caverns. On May 2, 1961, Utah Construction won the bid for the excavation work of the granite mountain. Workers blasted and removed one million tons of granite from inside the mountain. In February 1963, another bid opening placed interior construction work in the hands of Continental Consolidated Corporation. Eleven underground steel buildings were constructed to provide 170,000 square feet of space. To absorb shock waves, each building was mounted on giant steel springs. By February 1966, the "rock" was completed and NORAD began to shift operations from Ent AFB. 60

In 1966, Secretary of the Air Force Harold Brown proposed a plan that he hoped would overcome McNamara's aversion to air defense. Brown identified survivability, low-altitude detection, responsiveness, and costs as major flaws in the air defense system. In addressing these problems, Brown saw emerging technologies as the key to a more cost-effective and efficient air defense system. Brown's plan also called for phasing out most military radars around the nation's periphery. Detection duties would be assumed by FAA radars that would feed information into military control centers. To detect low-flying aircraft, Over-The-Horizon-Backscatter (OTH-B) radars were recommended. OTH-B stations would aim powerful radio beams and bounce them off the ionosphere back down on to the earth's surface. In theory, these radars would detect aircraft flying at any altitude at ranges out to 2,000 miles.

Brown's plan also pushed for procurement of the AWACS system for survivable command and control capability. Finally, Brown proposed development of the F-12 interceptor to replace aging fighter aircraft in the inventory. 61

Secretary McNamara approved Brown's plan. He was quick to initiate those portions that cut expenses. Radar stations were closed, and of those that remained, only twenty-two received the BUIC II automated, interception-control capability. By 1968, only radar stations around the nation's perimeter remained in Air Force jurisdiction. All gap-filler radars ceased operations. Interior stations were either closed or turned over to the FAA. However, with the Vietnam War absorbing more defense dollars, McNamara held off on the expenditure portions of Brown's plan. The AWACS and OTH-B program funding was stretched out over several years to support research and development. The F-12 interceptor program eventually was canceled. 62

In 1968, ADC became Aerospace Defense Command. However, Aerospace Defense Command fared no better under President Richard M Nixon's new administration than the ADC had under President Lyndon B Johnson's. Budget cuts closed down additional radar sites located along the southern perimeter of the country, such as Thomasville, Alabama, and Mount Lemmon, Arizona. By the start of 1970, the number of SAGE centers in the continental United States had been reduced to six: McChord AFB, Washington; Luke AFB, Arizona; Malmstrom. AFB, Montana; Duluth International Airport, Minnesota; Hancock Field near Syracuse, New York; and Fort Lee AFS in Virginia. These six remaining SAGE sites still used the vacuum tube Whirlwind II computers." 63

The ABM Treaty, signed in Moscow in 1972, limited the number of US and Soviet ABM sites to one per country. The treaty signified the ultimate triumph of the offense over defense advocates as national leaders acknowledged that missile defenses were futile. Having adopted the attitude that no defense was possible against missile attacks, national defense strategists determined that continued bomber defenses were also a waste of expenditures. With no new aircraft, interceptor squadrons became antiquated. Many squadrons were disestablished or turned over to the Air National Guard. In 1974, Nike and BOMARC missile defense bases were closed. With the exception of a BUIC III at Tyndall AFB, ADCs BUIC III capability was mothballed. AWACS development continued to be limited to the research and development phase. Once these aircraft finally entered production in the mid-1970s, they were assigned to TAC. OTH-B continued as are search and development project. 64

In one region of the country during this period, air defenses received a boost. On October 26, 1971, a Cuban aircraft landed in New Orleans after flying completely undetected through American airspace. Publicity and political pressure from Louisiana Congressman R Edward Hebert forced the Air Force to redeploy aircraft and radars. Subsequently, the Air Force established the Southeast Air Defense Sector and reopened a radar network along the Gulf coast. 65

Missile Detection and Defense

The Soviet ICBM threat dramatically changed US priorities to building detection and defensive capabilities against ballistic missile attack. Although Sputnik shocked the national psyche, the potential threat of intercontinental ballistic missiles had long been anticipated. Since the German V-2 campaign against England towards the end of World War II, military planners had been working with scientists and engineers to develop an antiballistic missile strategy.

Before the advent of the SS-6 Sapwood and Sputnik, both the Army and the Air Force had been conducting research and development programs leading to an antiballistic missile. The Air Force program, called "Project Wizard," was conceptual in nature. Project Wizard spent millions of dollars in various research labs to develop new technologies to counter the enemy threat. In contrast, the Army program, called "Nike Zeus," was more hardware oriented, building on technology of the earlier Nike Ajax and Nike Hercules antiaircraft missile programs.

In 1958, in the wake of Sputnik, President Eisenhower directed the cancellation of Project Wizard in favor of the Army Nike Zeus program. However, to defend against an attack, the United States needed the capability to detect an attack. Americans feared a nuclear Pearl Harbor, where without warning, nuclear bombs could drop from space, devastating American cities and crippling the military's ability to launch a counterattack. Without the means to defend against such an attack, Americans could only hope that the threat of massive retaliation would deter the Soviet Union from launching such a strike. Early warning would be critical to prepare the nation for the initial blow and allow SAC bombers to get off the ground.

Congress quickly approved funding to construct a Ballistic Missile Early Warning System (BMEWS). Radio Corporation of America (RCA) would develop and build the AN/FPS-49 tracking radars, GE and MIT would design and construct the AN/FPS-50 detection radars, and Western Electric would build the communication systems to connect the radars with command centers. Construction began immediately in the summer of 1958.

BMEWS required building installations at three locations to cover possible flight paths of missiles launched from the Soviet Union. Site I at Thule, Greenland, would host both AN/FPS-49 and AN/FPS-50 radars and receive top construction priority. Providing coverage for most missile approaches from the Eurasian landmass, the Thule site reached initial operating capability in October 1960. Clear, Alaska was selected for Site II to provide warning against missiles launched from the far eastern Siberia region. Initially hosting only AN/FPS-50 detection radars, the Alaskan site began operating in late 1961. Site III, at Fylingdale Moor, Yorkshire, England, was operational in September 1963. At Fylingdale Moor, AN/FPS-49 tracking radars provided coverage of ICBMs launched at the United States from the far western Soviet Union and provided an alert for Europeans if the Soviets launched intermediate range missiles at targets in western Europe. 67

Construction at the ICBM detection station at Clear began in August 1958. Located eighty miles southwest of Fairbanks, the station consisted of dormitories, administrative buildings, storage warehouses, recreational facilities, radar buildings, transmitter and computer buildings, fuel facilities, and three huge fence antenna components of the AN/FPS-50.

Designed by GE and MIT's Lincoln Laboratory, the three fixed-in-place fence antennas stood 165 feet tall and 400 feet wide. These curved arrays sent two fan-shaped beams at differing angles beyond the earth's atmosphere. When an object passed through the lower-angled beam, the reflected radar pulses were picked up by supersensitive antennas and passed on to computers that determined the object's position and velocity. When objects passed through the higher-angled second beam, computers received additional information to determine trajectory, speed, impact point, impact time, and launch point. In 1966 a tracking radar was added to the site when Clear received an updated version of the AN/FPS-49. Designated as the AN/FPS-92, this tracking radar featured a movable antenna that locked onto objects identified by the detection radar. This provided additional data to NORAD headquarters. 68

NORAD received additional contributing sensors. In July 1973, Raytheon won a contract to build a system called "Cobra Dane" on Shemya Island in the Aleutian Islands off the Alaskan coast. Designated as the AN/FPS-108, Cobra Dane replaced AN/FPS-17 and AN/FPS-80 radars placed at Shemya in the 1960s to track Soviet missile tests and to support the Air Force Space track System. Becoming operational in 1977, Cobra Dane also had a primary mission of monitoring Soviet tests of missiles launched from southwest Russia aimed at the Siberian Kamchatka peninsula. This large, single-faced, phased-array radar was the most powerful ever built. 69

In 1976, the Air Force began operating the Perimeter Acquisition Radar attack Characterization System (PARCS). The story of how the Air Force came to possess this huge, phased-array radar traces its roots back to the 1950s.

In February 1955, the Army contracted Bell Telephone Laboratories to develop an ABM system. This system would be built on the technologies obtained during Nike Ajax and Nike Hercules system development. However, the Nike Zeus system developed by Bell never deployed. Acting on advice that immediate deployment was not technically feasible at an acceptable cost, President Eisenhower decided in May 1959 to maintain Nike Zeus as a research and development program.

By January 1963, the research and development program had evolved into "Nike X" On September 18, 1967, Defense Secretary McNamara acknowledged that ABM defenses could still be overwhelmed by a massive Soviet ICBM attack. However, the emergence of a Chinese nuclear threat could be countered by deploying the Nike X system, renamed the Sentinel, around major metropolitan areas.

On March 14, 1969, the Nixon administration canceled the Sentinel deployment scheme. Instead ABM defense was deployed under the name "Safeguard" to protect America's strategic missile forces. Minuteman missile silos surrounding Grand Forks AFB, North Dakota, and Malmstrom AFB, Montana, would be the first to receive ABM defense. 70

As a result of the 1972 ABM agreement, the United States completed work only at the site north of Grand Forks. Declared operational in 1975, the Grand Forks ABM site, armed with 100 defending missiles, could provide only a limited defense against the hundreds of warheads that the Soviets could employ. Furthermore, nuclear war scenarios foresaw the radar complexes coming under immediate attack, rendering the intercepting missiles useless. Faced with this futile situation, the Army wanted to operate the system for at least a year and then incorporate the lessons learned for a follow-on system. However, Army plans were cut short on October 2, 1975, when Congress voted to deactivate the site within the following year. Eventually the Air Force assumed operations of Safeguard's Perimeter Acquisition Radar (PAR) and redesignated the site as Cavalier Air Force Station. From its North Dakota location, PARCS provided additional polar coverage to support BMEWS. 71

BMEWS, along with additional sensors, gave NORAD the capability to warn the National Command Authority of an attack launched from the Soviet Union. However, the Soviet Union could attempt to circumvent the warning system using different geographical approaches. The Cuban Missile Crisis of the fall of 1962 was one such attempt. The placement of intermediate range ballistic missiles in Cuba illustrated the vulnerability of the United States to an attack along its unprotected southern border. Only after a highs takes showdown between the two superpowers, were the missiles removed.

In the wake of the Cuban Missile Crisis, an AN/FPS-85 long-range phased-array radar was constructed at Eglin AFB in Florida. Designed by Bendix Corporation, the radar consisted of a large square transmitter array placed alongside an octangular receiving array mounted on a large structure facing the Gulf of Mexico. The structure hosting the radar burned in 1965, but was rebuilt and placed back in operation in 1969. This radar also served as the main sensor for the Air Force's Spacetrack System and watched the skies over Cuba and the Gulf. 72

The American triumph of keeping Soviet nuclear launch platforms out of Cuba and at a distance would be short-lived and American defense planners knew it. During the early 1960s, Soviet scientists and engineers worked feverishly to design and build Soviet ballistic missile submarines capable of launching missiles from relatively short distances off America's coastlines. Once again the United States needed the capability to detect incoming missiles to prevent the specter of an atomic sneak attack. In December 1961, the Air Force asked ADC for an evaluation of the capability of FD radars to detect Submarine-Launched Ballistic Missiles (SLBMs). Subsequently, AN/FPS-35 search radars located at Manassas, Virginia, and Benton, Pennsylvania, received modifications and began to be tested during the summer of 1962. During these tests, both radars attempted to track Polaris, Minuteman, Titan, and the Thor-Delta missile launched from Cape Canaveral, Florida. The tests revealed that the AN/FPS-35 had only marginal ability to detect missile launches. 73 However, using AN/FPS-35 or AN/FPS-24 FD radars to detect SLBMs continued to be considered a viable option given the fiscal constraints imposed on ADC.

Another option to detect SLBMs that was favored by ADC was to procure a series of AN/FPS-49 radars. One of these units had been operating since 1961 at Moorestown, New Jersey, as the original sensor for the Air Force's Spacetrack System. To ADC's disappointment, a study by the Electronic Systems Division at Hanscom AFB, Massachusetts, revealed that using the Moorestown radar for dual use was infeasible. 74

The long-tem vision of ADC planners foresaw SLBM detection as a collateral mission of the OTB-B radar that was still under development. However, ADC could not wait for a system that still was in the research and development stage. In November 1964, desperate to field at least an interim system to warn the nation of a SLBM attack, ADC sought and received permission from the office of the Secretary of Defense to modify existing SAGE system radars. 75

In the ensuing months, makers of the various SAGE-compatible radar systems submitted proposals on the modifications that would enable their products to detect an object of at least two meters in size, at a range of 750 miles, within six seconds after launching. The radar then would continuously track this object within ten seconds of detection and notify NORAD Combat Operations Center within sixty seconds.

In July 1965, the Air Force selected Avco Corporation for an innovative proposal employing its AN/FPS-26 height-finder radar to detect SLBMs. The modified AN/FPS-26 radar system (redesignated as the AN/FPS-7) was slated for deployment at Point Arena. California; Mount Laguna California; Mount Hebo, Oregon; Charlestown, Maine; Fort Fisher, North Carolina; MacDill AFB, Florida; and Laredo Texas. 76

After years of testing and evaluation, the seven-site SLBM detection system became fully operational in 1971. A year later, twenty percent of the surveillance capability of the AN/FPS-85 located at Eglin AFB, Florida, also became dedicated to search for SLBMs. 77

During the 1970s, the Soviets developed SLBMs that could be launched from greater distances away from the American Coastline. For example, the Soviet Delta I class ballistic missile submarine carried the SS-N-8 missile that had a range of over 4,000 nautical miles. This was beyond the detection capability of either the AN/FPS-7 or the OTH-B radar system being developed. 78 Consequently, the Air Force had to turn to another solution.

The solution was a phased-array warning system to become known as "PAVE PAWS" (Perimeter Acquisition Vehicle Entry Phased-Array Warning System). Originally designed as a two-site system, PAVE PAWS sites were constructed in the late 1970s at Otis AFB, Massachusetts, and Beale AFB, California. From a distance, the PAVE PAWS structure looked like a three-sided pyramid with a flattened top. On the two seaward faces of the pyramid, Raytheon installed the AN/FPS-115 with its phased-array antenna. Thirty meters in diameter and consisting of 2,000 elements, each antenna could detect objects launched as far away as 3,000 miles. The Otis site became operational in 1979 and the Beale site became operational a year later.

A contract for two more continental PAVE PAWS sites, was awarded in 1984. An AN/FPS-115 at Robins AFB, Georgia, became operational in 1986 and another unit at Eldorado AFS, Texas, was activated in 1987. Additional AN/FPS-115 PAVE, PAWS radars were installed in the 1990s at BMEWS sites at Thule, Greenland, and Fylingdale Moor, England, to assume the ICBM detection mission. As PAVE PAWS sites in the United States were activated, the older AN/FPS-7 radars were phased out, except for the MacDill AFB site that continued to provide additional coverage over Cuba. 70

Space tracking and missile detection functions of the former Aerospace Defense Command were assumed by SAC in 1980. Control of these facilities became an Air Force Space Command responsibility with the activation of that command on September 1, 1982.

Looking to the Future

In March 1983, President Ronald W Reagan announced his controversial Strategic Defense Initiative (SDI). Although SDI focused on ballistic missile defense, the implications for air defense were profound. Air Force Director of Plans Major General John A Shaud observed that a ballistic missile defense system would have to be complemented by an air defense system. He stated "If you're going to fix the roof, you don't want to leave the doors and windows open." 80 Thus the efforts rooted in the 1966 Brown Plan would finally come to fruition during the 1980s and early 1990s.

Rebuilding the Network

Steps were taken to improve the air defense warning system long before President Reagan announced his Strategic Defense Initiative. The absorption of ADCOM into TAC in 1980 came during the transition to a system that had been envisioned by the Brown Plan over a decade earlier. The DoD and the FAA had been negotiating throughout the 1970s for the FAA to assume control of most tracking duties as part of a proposed Joint Surveillance System. To create the JSS, during 1979 and 1980 TAC closed down twenty-seven SAGE radar sites. Some of these sites were retained to become FAA-operated JSS sites. In other cases, the former ADCOM sites were placed in caretaker status. At some operational FAA sites, a small Air Force detachment arrived to install and operate a height-finder radar. Radars built for the FAA did not have a height-finding capability.

In the early 1980s, when the JSS project was completed, the JSS operated forty-six long-range radar sites. Thirty-one of the sites had FAA-operated search radars and Air Force-manned height-finder radars. Five sites had FAA radars that simply provided a data tie to one of the SAGE Regional Control Centers (RCC). The ten remaining long-range radar sites were operated by the military. Six of those sites were operated by the Air Force. The Oceana Naval Air Station site in Virginia was jointly operated by the Navy and Air Force. Contractors operated a radar at Lake Charles, Louisiana, and Civil Service personnel operated a radar at Point Arena, California. The remaining DoD site, at Cudjoe Key, Florida, used a radar that was flown within an aerostat balloon. 81

Initially, these forty-six radar sites provided data feeds to the six remaining SAGE ROCCs. During 1983, these six ROCCs were replaced by four Region Operation Control Centers (ROCCs) that operated as part of the JSS.

Within the continental United States, ROCCs were located at Griffiss AFB, New York; March AFB, California; Tyndall AFB, Florida; and McChord AFB, Washington. Additional ROCCs were located in Alaska and Hawaii. Canada established two ROCCs collocated at North Bay, Ontario. Like the ROCCs of the previous SAGE system, these ROCCs were "soft," meaning that they were vulnerable to nuclear attack. Consequently, the centers were designed for peace time use to detect, track, and identify intruding aircraft, and if needed, to deploy and direct interceptor aircraft to challenge an intruder. If the United States became threatened by a direct attack, the ROCCs had the capability to transfer command and control function to an airborne AWACS aircraft. 82

The ROCCs saved millions of dollars over the previous system. In contrast to the Whirlwind 11 computer that occupied a half-acre of space within the old SAGE block-houses, the more capable computers for the ROCCs occupied the space of a vending machine. ROCC computer components were also more readily available than the SAGE vacuum tubes that often had to be procured from eastern bloc countries. Not only was the new computer more capable, but it allowed ROCC watch standers to perform their duties in normal room temperatures. To maintain the earlier Whirlwind II computer, huge air conditioning units kept the vacuum tubes and the watch standers in a cool environment. 83

As these ROCCs became operational, TAC made additional cuts; deactivated remaining continental radar squadrons and disestablished detachments that had operated height-finder radars at the FAA-operated joint-use sites. By 1987, the four ROCCs relied mostly on data-feeds from the FAA JSS radars. Technological advances allowed for these equipment and manpower reductions and improved US detection and tracking capabilities. For example, in July 1988, Westinghouse Electric Corporation received a contract to build forty ARSR-4 radar systems for installation at JSS sites around the periphery of the nation. A 3-D radar, the ARSR-4 was the first radar truly capable of meeting both the air traffic control and air defense requirements for the FAA and Air Force. With the installation of these units during the mid-1990s, radars of the 1950s and 1960s vintage finally could be retired. 84

In addition to establishing the JSS system, the Air Force implemented another of the 1966 Brown recommendations: construction of east and west coast OTH-B sites. In 1975, GE Aerospace received the contract to build a prototype OTH-B system. The transmitter site was built at Moscow AFS, Maine, and the receiver site was constructed at Columbia AFS, Maine. Initial testing occurred in 1980. With successful test trials, GE Aerospace received a contract in 1982 to build a full-scale model of the system designated as the AN/FPS-118. The east coast system achieved limited operational capability in 1988. Two years of testing and evaluation on the east coast yielded improvements for the west coast system that was undergoing construction. The Air Force accepted the east coast system from the contractor in April 1990.

The west coast OTH-B operations center was located at Mountain Home AFB in Idaho. The transmitter was placed at Christmas Valley, Oregon, and the receiver was erected at Tule Lake near Alturas, California. The west coast system was accepted by the Air Force at the end of 1990.

In March 1991, a diminished threat led to a recommendation to scrap the whole system. However, the Air Force decided to conduct limited operations on the east coast and preserve the system in a maintenance status on the west coast. 85

The blockhouses that once hosted SAGE centers remain intact at many locations, although the Whirlwind II computers and command consoles have long been removed. The four ROCCs built during the 1980s remain intact and operational. The intruding aircraft in the 1990s represent a different threat; attempting to smuggle illegal drugs into the country.

The BMEWS system will remain intact for the foreseeable future as long as more countries gain the capability to launch ballistic missiles. Cheyenne Mountain, Colorado, still serves as the nerve center for North America's missile tracking sensors.

Historians will long argue what brought about the demise of the Soviet Union and why World War III never was fought. While one school argues that the Soviet system collapsed under its own weight of inefficiency, another school vigorously contends that American military vigilance significantly contributed to the Soviet demise.

Nuclear deterrence, it is argued, eliminated direct military confrontation as an option for the Soviets. If such is the case, then the role of the thousands of men and women who operated the radar stations and command centers during the Cold War cannot be overlooked. They contributed to the deterrence in two ways. First, by being able to direct interceptor forces against intruding aircraft, the air defenders reduced the opponent's confidence level for mission success. Second, and more importantly, the warning provided by the air defense and later missile defense warning sensors gave America's nuclear forces the forewarning necessary to deliver a devastating retaliatory blow.

When viewing the hundreds of abandoned air defense structures dotting the American landscape, one should reflect on the roles of the thousands of men and women who operated the air defense systems. Part of their legacy is their contribution to the United States' triumph in the Cold War.

1. Kenneth Schaffel, "The US Air Force's Philosophy of Strategic Defense: A Historical Overview," in Strategic Air Defense, Stephen J Cimbala ed., (Wilmington, DE: Scholarly Resources Inc.. 1989), p. 5; A Hand-book of Aerospace Defense Organization, 1946-1986, (Peterson Air Force Base, CO: Office of History Air Force Space Command, 1987), p. 1.

2. Sean S Swords, Technical History of the Beginnings of Radar (London: Peter Peregrinus, 1986), pp.

112-16. A detailed account of the Army effort is provided in Harry M Davis, History of the Signal Corps Development of the US Army Radar Equipment: Research and Development, 1918-1937 (Part I) (Washington: Office of the Chief Signal Corps Officer, Historical Section Special Activities Branch, 1944); and

Dulany Terrett, United States Army in World War H.- The Signal Corps-The Emergency (7b December 1941) (Washington: Office of the Chief of Military History, 1956).

3. Schaffel, Strategic Air Defense, pp. 7-9; Norman Friedman, Naval Radar (Annapolis, MD: Naval Institute Press, 1981), pp. 80-82, 88n. Two works covering Naval Research Laboratory radar work include David K Allison, A New Eye for the Navy: The Origin of Radar at the Naval Research Laboratory, NRL Report 8466(Washington: US Government Printing Office, 1981), and Louis A Gebhard, Evolution of Naval-Electronics and Contributions of the Naval Research Laboratory, NRL Report 8300 (Washington: US Government Printing Office, 1979). Bell Laboratories contributions are covered in MD Fagan, ed., A History of Engineering and Science in the Bell System: National Service in War and Peace (1925-1975) (New York: Bell Telephone Laboratories, 1978).

4. Edwin T Layton, "And I Was There": Pearl Harbor and Midway-Breaking the Secrets (New York, NY: William Morrow and Company, Inc. 1985), p. 308.

5. Friedman, Naval Radar, pp. 87-88.

6. Schaffel, Strategic Air Defense, pp. 10-12. See also Chapter 1 in Schaffel's The Emerging Shield: The Air Force and the Evolution of Continental Air Defense, 1945-1960 (Washington, DC: Office of Air Force History, 1991) and A Handbook of Aerospace Defense Organization, pp. 4-5.

7. Merrill 1. Skolnik, "Fifty Years of Radar," Proceedings of the IEEE (February 1985), pp. 183-84. For a detailed look at Radiation Laboratory activity see Five Years at the Radiation Laboratory (Boston: 1991 IEEE MIT-S International Microwave Symposium 1991).

8. A Handbook of Aerospace Defense Organization, p. 4.

9. Schaffel, The Emerging Shield, pp. 47-48; Richard F McMullen, "The Aerospace Defense Command and Anti-Bomber Defense, 1946-1972," ADC Historical Study No. 39, 1973, p. 2.

10. Richard F McMullen, "Radar Programs for Air Defense, 1946-1966," ADC Historical Study No. 34 (1966),pp. 1-2.

11. Schaffel, The Emerging Shield, pp. 54-55; McMullen, "Radar Programs," p. 3; McMullen, "Anti-bomber Defense," pp. 2-5.

12. Schaffel, The Emerging Shield, pp. 61-63; McMullen, "Radar Programs," pp. 5-8; McMullen, "Anti-bomber Defenses," pp. 14-15; "Hearings before the Subcommittee of the House Committee on Appropriations for the Military Establishment," February 17, 1947, p. 629.

13. Schaffel, The Emerging Shield, pp. 67-68; McMullen, "Radar Programs," pp. 9-10; McMullen, "Anti-bomber Defense," pp. 19-20.

14. McMullen, "Radar Programs," p. 8; Schaffel, The Emerging Shield, p. 77; McMullen, "Anti-bomber Defense," p. 22. 15. Schaffel, The Emerging Shield, p. 78; McMullen, "Radar Programs," pp. 12-13, 16-18; McMullen, "Anti-bomber Defenses," pp. 30-31.

16. Schaffel, The Emerging Shield, pp. 91-93.

17. Schaffel, The Emerging Shield, pp. 95-96; McMullen, "Radar Programs," P;. 18-19.

18. Schaffel, The Emerging Shield, pp. 107-110; McMullen, "Radar Programs, pp. 23-24.19. McMullen, "Radar Programs," p. 26.

20. Schaffel, The Emerging Shield, pp. 120-2 1.

21. Schaffel, The Emerging Shield, pp. 129, 134-35; Lieutenant Colonel Steve Moeller, Vigilant and Invincible: The Army's Role in Continental Air Defense, 1950-1974 (Columbus, OH: Ohio State University Master's Thesis, 1992), pp. 21-27.

22. McMullen, "Radar Programs," pp. 27-28.

23. Ibid., pp. 30-32, 34.

24. Schaffel, The Emerging Shield, pp. 140-4 1.25. McMullen, "Radar Programs," pp. 44-45.

26. McMullen, "Radar Programs," p. 47; Schaffel, The Emerging Shield, pp. 155-56.

27. Schaffel, The Emerging Shield, pp. 144-45, 150; "The Truth About Our Air Defense," Air Force (May 1953),p. 29; McMullen, "Anti-bomber Defense," pp. 50-53.

28. Schaffel, The Emerging Shield, p. 205; Eva C Freeman, ed., MIT Lincoln Laboratory: Technology in the National Interest (Lexington, MA. Lincoln Laboratory, Massachusetts Institute of Technology, 1995), pp. 15, 17.

29. Schaffel, The Emerging Shield, pp. 150-51, 169-7 1.

30. Richard Morenus, The DEW Line: Distant Early Warning, The Miracle of Americas First Line of Defense (New York, NY Rand McNally and Company, 1957), Chapter 2; Schaffel, The Emerging Shield, pp. 174-77.

3 1. Schaffel, The Emerging Shield, pp. 185-86.

32. Ibid., pp. 190-191, 193; McMullen, "Anti-bomber Defense," pp. 55, 59-64.

33. McMullen, "Radar Programs," pp. 57-58; Schaffel, The Emerging Shield, p. 193.

34. Schaffel, The Emerging Shield, p. 194; Frederic H. Smith, Jr. 'How Air Defense Is Part of the Great Deterrence, "Air Force (June 1956), pp. 90-91, 93.

35. McMullen, "Radar Programs," pp. 57-58.

36. Virge Jenkins Temme, et al., Historical and Architectural Documentation Reports of North 7) Air Force Station, North , Massachusetts (Langley AFB, VA Headquarters, Air Combat Command, 1995), pp. 7-9; Morenus, DEW Line, Chapter 1.

37. Schaffel, The Emerging Shield, pp. 203-5; Freeman, MIT Lincoln Laboratory, pp. 25, 27.

38. McMullen, "Radar Programs," pp. 77-78; Schaffel, The Emerging Shield, pp. 214-16; DEW Line construction is discussed in Charles Corddry, "How we're building the world's biggest Burglar Alarm," Air Force (June 1956); and Howard La Fay, "DEW Line, Sentry of the Far North," The National Geographic Magazine, (July 1958).

39. McMullen, "Radar Systems," pp. 70-71.40. Ibid., pp. 59-61, 71.

41. Ibid., pp. 87,105,126.

42. Historical Data of the Aerospace Defense Command, 1946-1973, p. 78; Schaffel, The Emerging Shield, p. 222.

43. Letter dated October 31, 1995, from NORAD historian Dr. Thomas Fuller to author.

44. Richard F McMullen, "Air Defense and National Policy: 1958-1964," (ADC Historical Study No. 26, 1965),p. 45.

45. McMullen, "Radar Programs," p. 23 1.

46. Russell F Weigley, in The American Way of War: A History of United States Military Strategy and Policy (New York, NY 1973), argues that offensive doctrine has prevailed throughout American military history

47. Schaffel, The Emerging Shield, p. 261.

48. McMullen, "Radar Programs," pp. 138-39.49. Ibid., pp. 140-42, 152, 167-68.50. Ibid., pp. 155-56, 180-8 1.

51. Robert Frank Futrell, Ideas, Concepts, Doctrine: Basic Thinking in the United States Air Force (Maxwell Air Force Base, Montgomery, AL: Air University Press, [197111989), pp. 532-33.

52. Richard F. McMullen, "Command and Control Planning: 1958-1965," ADC Historical Study No. 35, (1965), pp. 1- 11.

53. Ibid., pp. 15-16.54. Ibid., pp. 26-27.55. Ibid., p. 38.

56. Ibid., pp. 43-45.57. Ibid., pp. 50-55.58. Ibid., pp. 57-64.

59. "Declaration of Excess Real Property North Truro Air Force Station, North Truro Massachusetts, 18 June 1984," p. 5.

60. The Federal Engineer Damsites to Missile Sites: A History of the Omaha District US Army Corps of Engineers (Omaha, NE: US Army Engineer District Omaha, 1984), pp. 199-213; Stanley L. Englebardt, Strategic Defenses (New York, NY. Thomas Y Crowell Company, 1966), pp. 136-39; "Cheyenne Mountain Complex Chronology" (July 1994) provided by United States Space Command.

61. Owen E Jensen, "The Years of Decline: Air Defense from 1960 to 1980," in Strategic Air Defense, Stephen J Cimbala, ed. (Wilmington DE: Scholarly Resources Inc. 1989), pp. 32-35.

62. Ibid., p. 38.

63. Headquarters Aerospace Defense Command Press Release (undated) located at the Air Force Museum Research Center collection File L2 Command Air Defense.

64. Jensen, 'Years of Decline," pp. 23-24, 38-39.

65. Ibid., pp. 39-40; Claude Witze, "The Gaps in Our Defense," Air Force (March 1972), pp. 33-39.66. Jensen, The Years of Decline," pp. 40-41; A Handbook of Air Defense Organization, p. 6.

67. Englebardt, Strategic Defenses, pp. 107-8; A Handbook of Aerospace Defense Organization: 1946-86, pp. 22, 24.

68. Denfield, Cold War in Alaska, pp. 40-41; Englebardt, Strategic Defenses, pp. 108-110; Jane's, p. 79; Schaffel, The Emerging Shield, pp. 257-60.

69. Jane's Radar and Electronic Systems, 6th edition, Bernard Blake, ed. (1994), p. 78.

70. Donald Baucom, The Origins of SDI, 1944-1983 (Lawrence, KS: University Press of Kansas, 1992) provides an excellent integration of the political and technical aspects of the program.

71. James H. Kitchens, III, A History of the Huntsville Division, US Army Corps of Engineers, 1967-1976 (Huntsville, AL: US Army Corps of Engineers Huntsville Division, 1978), pp. 111-12; Letter dated May 2,1996 from Mandy Whorton, Argonne National Laboratory to Virge Jenkins-Temme, USACERL.

72. Jane's, p. 80.

73. McMullen, "Radar Programs," pp. 171-74.

74. Ibid., pp. 188-9 1. The Moorestown AN/FPS-49 radar was phased out in 1969 once the AN/FPS-85 phased array radar at Eglin, Air Force Base assumed Spacetrack duties. See "Headquarters Aerospace Defense Command News Release 10-28-209-APM," at Research Center, Air Force Museum, Wright-Paterson Air Force Base, folder L2 Command Air Defense.

75. McMullen, "Radar Programs," pp. 205-6.76. Ibid., pp. 224--25.77. Jane's, p.31.

78. Understanding Soviet Naval Developments, 3rd ed. (Washington, DC: Office of the Chief of Naval Operations, 1978), p. 73.

79. Jane's, p. 81; "PAVE PAWS Radar System," United States Air Force Fact Sheet (Peterson, AFB, CO: Office of Public Affairs, Air Force Space Command, 1992).

80. Rick Atkinson, "Air Defense for Continental US Is Coming Back Into Vogue," The Washington Post(August 25, 1984), p. A4.

81. From "JSS documents," provided by Air Combat Command History Office 82. Jane's, p. 32.

83. Marilyn Silcox, "Southeast ROCC Marks Beginning of New Air Defense Era," National Defense (July-August 1984), pp. 42-43, 46; Rick Atkinson, "Air Defense for Continental US Coming Back Into Vogue," The Washington Post (August 25, 1984), p. A4.

84. Jane's, p. 85.

85. Ibid., pp. 82-83.

RADAR SYSTEMS CLASSIFICATION METHODS

During World War II, each service used its own method to designate its electronic radar/tracking systems. For example, Army radars were classified under the initials SCR, which stood for "Signal Corps Radio". Different designations for similar systems confused manufacturers and complicated electronics procurement. In February 1943, a universal classification system was implemented for all services to follow, ending the confusion. To indicate that an electronic system designation followed the new universal classification, the letters "AN," for Army-Navy, were placed ahead of a three-letter code. The first letter of the three-letter code denoted the type of platform hosting the electronic device, for example: A=Aircraft; C=Air transportable (letter no longer used starting in the 1950s); F=Fixed permanent land-based; G=General ground use; M=Ground mobile; S=Ship-mounted; T=Ground transportable. The second letter indicated the type of device, for example: P=Radar (pulsed); Q=Sonar; R=Radio. The third letter indicated the function of the radar system device, for example: G=Fire control; R=Receiving (passive detection); S=Search; T=Transmitting. Thus an AN/FPS-20 represented the twentieth design of an Army-Navy "Fixed, Radar, Search" electronic device.

World War II Radars

This section describes the World War II vintage radars that saw service during the Cold War. The systems are listed in numerical order, bypassing the three-letter code. During World War II, search and height-finder radars became components of America's electronic arsenal. The function of the search radar was to detect and obtain a line of bearing on an aircraft. Early models such as the SCR-270 and 271 looked like large bed-springs. Later designs, such as the AN/CPS-5 looked like a large oval dish. Search radars generally rotated full circle around a central axis. In contrast to the rotating search radar antenna, the horizontally mounted height-finder radar focused on the tracked aircraft's reported bearing. The radar antenna dish then scanned up and down to provide the operators with the estimated height of the aircraft.

AN/TPS-lB, 1C, 1D

Bell Telephone Laboratories developed this radar that subsequently was produced by the Western Electric Company. A crew of two could operate the radar. The 1B model could detect bombers at 10,000 feet at a distance of 120 nautical miles. The height detection and range on the 1C and 1D models exceeded those of the 1B. The transmitter sent its pulse at an L-band frequency between 1220 to 1280 megahertz (MHz). This long-range search radar was used in the temporary Lashup system beginning in 1948.

AN/CPS-4

Developed by MIT's Radiation Laboratory, this height-finding radar was nicknamed "Beaver Tail." The radar was designed to be used in conjunction with the SCR-270 and SCR-271 search sets. The CPS-4 required six operators. This S-band radar, operating in the 2700 to 2900 MHz range, could detect targets at a distance of ninety miles. The vertical antenna was twenty feet high and five feet wide. This radar was often paired with the AN/FPS-3 search radar during the early 1950s at permanent network radar sites.

AN/CPS-5

Bell Telephone Laboratories and General Electric developed this search radar. General Electric began producing sets in January 1945. Designated as a transportable medium-range search radar, the unit was ideal for use in the Lashup system in conjunction with the AN/TPS-10 height-finder radar. It could be operated with a crew of ten. Some of these units remained to serve in the first permanent network. Designed to provide a solid search of up to 60 miles at 40,000 feet, the radar often had success tracking aircraft as far as 210 miles away.

AN/CPS-6, 6A, 6B

The AN/CPS-6 was developed during the later stages of World War II by the Radiation Laboratory at MIT. The first units were produced in mid-1945. General Electric developed and produced the A-model and subsequent B-model at a plant in Syracuse, New York. The unit consisted of two antennas. One of the antennas slanted at a forty-five degree angle to provide the height-finder capability. Initially, the radar was designed to detect fighter aircraft at 100 miles and 16,000 feet. The radar used five transmitters that operated at S-band frequencies ranging from 2700 to 3019 MHz. It took twenty-five people to operate the radar. An AN/CPS-6 radar was installed as part of the Lashup system at Twin Lights, New Jersey, in 1949 and proved capable of detecting targets at ranges of eighty-four miles. The first units of the follow-on 6B radar set were ready for installation by mid-1950. Fourteen 6B units were used within the first permanent network. A component designed to improve the radar's range was added in 1954. Initial tests showed the 6B unit had a range of 165 miles with an altitude limit of 45,000 feet. One radar unit and its ancillary electronic equipment had to be transported in eighty-five freight cars. The Air Force phased out the 6B model between mid-1957 and mid-1959.

AN/TPS-10, 1OA /AN/FPS-4

MIT's Radiation Laboratory developed and produced the first version of this radar near the end of World War II. Zenith produced the A-model sets in the post-war period. The vertically mounted antenna was three feet wide and ten feet long. Two operators were needed to run the set. The initial model operated at a frequency of 9000 to 9160 MHz and had a maximum reliable range for bombers of 60 miles at 10,000 feet. An updated version designated the AN/FPS-4 was produced by the Radio Corporation of America (RCA) beginning in 1948. Some 450 copies of this and the trailer-mounted AN/MPS-8 version were built between 1948 and 1955.

Early Cold War Search Radars

Early Cold War search radars essentially were advanced or improved versions of World War Il era sets. In some cases, the performance of the new sets fell short of expectations.

AN/FPS-3, 3A

The AN/FPS-3 was a modified version of the AN/CPS-5 long-range search radar. The first units came off the Bendix production line and were ready for installation in late 1950. Forty-eight of these L-band units were used within the first permanent network. The AN/FPS-3B incorporated an AN/GPA-27, which increased the search altitude to 65,000 feet. Installation of these modifications began in 1957.

AN/FPS-5

The AN/FPS-5 was a long-range search radar produced in the early 1950s by Hazel-tine. Deployment was limited.

AN/FPS-8

The AN/FPS-8 was a medium-range search radar operating on the L-band at a frequency of 1280 to 1380 MHz. Developed in the 1950s by General Electric, over 200 units of this radar were produced between 1954 and 1958. Variants of this radar included the AN/GPS-3 and the AN/MPS-11.

AN/FPS-10

This unit was essentially a stripped down version of the AN/CPS-6B. Thirteen of these units served within the first permanent network.

SAGE System Compatible Search Radars

Various manufacturers began design work on compatible search radars for SAGE systems in the mid-1950s in conjunction with the development of the SAGE Command and Control System. Because Project LAMPLIGHT indicated radar vulnerability to electronic countermeasures, the Air Force developed a series of radars that could shift frequency. These frequency-diversity (FD) radars included the AN/FPS-24, AN/FPS-27, and AN/FPS-35.

AN/FPS-7, 7A, 7B, 7C, 7D

In the mid-1950s, General Electric developed a radar with a search altitude of 100,000 feet and a range of 270 miles. This radar was significant in that it was the first stacked-beam radar to enter into production in the United States. Designed to operate in the L-band at 1250 to 1350 MHz, the radar deployed in late 1959 and the early 1960s. The AN/FPS-7 was used for both air defense and air traffic control in New York, Kansas City, Houston, Spokane, San Antonio, and elsewhere. In the early 1960s, a modification called AN/ECP-91 was installed to improve its electronic countermeasure (ECM) capability. About thirty units were produced.

AN/FPS-20, 20A, 20B

This Bendix-built radar was an AN/FPS-3 search radar with an AN/GPA-27 installed. Designed to operate in the L-band frequencies of 1250 to 1350 MHz, the radar had a range of over 200 miles. By the late 1950s this radar dominated the United States radar defense net. Deployment continued into the early 1960s. In June 1959, Bendix received a contract to provide private industry's MK-447 (the same as the military's AN/GPA-103) and MK-448 (AN/GPA-102) anti-jam packages to the radars. With the addition of these packages, the Air Force redesignated the radars. The AN/FPS-20A with the AN/GPA-102 became the AN/FPS-66 and the AN/FPS-20A with the AN/GPA-103 became the AN/FPS-67. Over 200 units were built.

AN/FPS-24

General Electric built an FD search radar designed to operate in the Very High Frequency (VHF) at 214 to 236 MHz. There were problems with this radar at the test site at Eufaula, Alabama, in 1960. These problems required many modifications. Additional problems occurred when deployment was attempted in 1961. When the radar finally deployed, bearing problems often occurred due to the eighty-five ton antenna weight. Twelve systems were built between 1958 and 1962.

AN/FPS-27, 27A

Westinghouse built an FD search radar designed to operate in the S-band at 2322 to 2670 MHz. The radar was designed to have a maximum range of 220 nautical miles and search to an altitude of 150,000 feet. System problems required several modifications at the test platform located at Crystal Springs, Mississippi. Once these problems were solved, the first of twenty units in the continental United States became operational a Charleston, Maine, in 1963. The last unit was installed at Bellefontaine, Ohio, a year later. In the early 1970s, AN/FPS-27 radar stations that had not been shutdown received a modification (solid state circuitry replacing vacuum tubes) that improved reliability and saved on maintenance costs.

AN/FPS-28

Raytheon designed this search radar to operate at 410 to 690 MHz. A test unit was placed at Huoma Naval Air Station (NAS) in Louisiana.

AN/FPS-30

Bendix built this long-range search radar that operated in the L-band.

AN/FPS-31

Designed by Lincoln Laboratory, this huge radar was designed to be compatible with the SAGE system. A prototype was built at Jug Handle Hill in West Bath, Maine. The antenna was 120 feet wide and 16 feet high. Operations began in October 1955. After a period of unexpected clutter, it was determined that the radar received echoes from the aurora borealis (Northern Lights) and this hindered tracking. Although this model was never mass-produced for active use, lessons learned from this radar would continue supporting SAGE system research and development.

AN/FPS-35

This Sperry-built FD long-range search radar was designed to operate at 420 to 450 MHz. It was first deployed in December 1960, but problems hampered the program. Four of these units were operational in 1962. The system suffered frequent bearing problems as the antenna weighed seventy tons.

AN/FPS-64, 65, 66, 67, 67A, 72

These radars were modified versions of the Bendix AN/FPS-20 search radar. See the AN/FPS-20 entry.

AN/FPS-87A

Bendix built this long-range L-band search radar that was based on the AN/FPS-20. See the AN/FPS-20 entry.

AN/FPS-88

General Electric produced this updated version of the AN/FPS-8 radar in the late 1960s. The AN/FPS-88 operated in the L-band at 1280 to 1380 MHz and featured some ECM capability.

AN/FPS-91

This radar was another version of the AN/FPS-20 search radar produced by Bendix. See the AN/FPS-20 entry.

AN/FPS-93

Raytheon modified the AN/FPS-20 radar to create this radar. See the AN/FPS-20 entry.

AN/FPS-100

This radar was another modernization of the Bendix AN/FPS-20 radar. See the AN/FPS-20 entry.

AN/FPS-107

This Westinghouse-built search radar operated in the L-band at 1250 to 1350 MHz.

SAGE System Compatible Height-finder Radars

To complement the search radars, height-finding radars were developed to detect aircraft at increasing altitudes. The AN/FPS-6 would serve as the standard model for much of the Cold War.

AN/FPS-6, 6A, 6B

The AN/FPS-6 radar was introduced into service in the late 1950s and served as the principal height-finder radar for the United States for several decades there after. Built by General Electric, the S-band radar radiated at a frequency of 2700 to 2900 MHz. Between 1953 and 1960, 450 units of the AN/FPS-6 and the mobile AN/MPS-14 version were produced.

AN/FPS-26

Avco Corporation built this height-finder radar that operated at a frequency of 5400 to 5900 MHz. This radar deployed in the 1960s.

AN/FPS-89

General Electric produced this improved version of the AN/FPS-6 height-finder radar in the early 1970s. Operating in the S-band, this high-power radar was capable of detecting targets at a range of over 110 miles.

AN/FPS-90

Martin Marietta produced the high-powered version of the AN/FPS-6 height-finder radar. See the AN/FPS-6 entry.

AN/FPS-116

This radar was another modernized version of the AN/FPS-6 height-finder radar. See the AN/FPS-6 entry.

Gap-Filler Radars

Gap-filler radars were designed to cover areas where enemy aircraft could fly low enough to evade detection by distant long-range search radars. Between 1957 and 1962, some 200 AN/FPS-14 and AN/FPS-18 models were built.

AN/FPS-14

This medium-range search radar was designed and built by Bendix as a SAGE system gap-filler radar to provide low-altitude coverage. Operating in the S-band at a frequency between 2700 and 2900 MHz, the AN/FPS-14 could detect at a range of 65 miles. The system was deployed in the late 1950s and 1960s.

AN/FPS-18

This medium-range search radar was designed and built by Bendix as a SAGE system gap-filler to provide low-altitude coverage. The radar operated in the S-band at a frequency between 2700 and 2900 MHz. The system deployed in the late 1950s and 1960s.

AN/FPS-19

This Raytheon gap-filler radar was deployed on the Distant Early Warning (DEW) Line. It operated in the S-band.

North Warning System Radars

AN/FPS-117

This 3-D long-range radar was built by GE Aerospace for use at Alaskan sites and on the Northern Warning System. The radar operated at 1215 to 1400 MHz and had a range of about 220 miles.

AN/FPS-124

This medium-range radar was built by Unisys to serve as an unmanned gap-filler radar on the North Warning System.

Ballistic Missile Early Warning System (BMEWS) Radars

With the advent of ballistic missiles, millions of dollars were spent to research, develop, test, and deploy BMEWS radars.

AN/FPS-7

This radar was a modified AN/FPS-26 height-finder radar produced by Avco Corporation to detect submarine-launched ballistic missiles. The system deployed at seven sites in the 1970s. Six sites were phased out during the early 1980s. The remaining unit continued in operation in the southeast for a few more years to provide coverage over Cuba.

AN/FPS-17

With the Soviet Union apparently making rapid progress in its rocket program, in 1954 the United States began a program to develop a tracking radar. General Electric was the contractor and Lincoln Laboratory was the subcontractor. This tracking radar, the AN/FPS-1 7, was conceived, designed, built, and installed for operation in less than two years. Installed at Laredo AFB in Texas, the first AN/FPS-17 was used to track rockets launched from White Sands, New Mexico. The radar was unique; it featured a fixed-fence antenna that stood 175 feet high and 110 feet wide. The transmitter sent out a pulse at a frequency between 180 to 220 MHz. Units were installed in the late 1950s at Shemya Island in the Aleutians and in Turkey. The unit at Shemya subsequently was replaced by the Cobra Dane (AN/FPS-100) radar.

AN/FPS-49, 49A

This large radar was built by RCA for use in the BMEWS program and the satellite-tracking program that deployed in the 1960s. The prototype unit operated at Moorestown, New Jersey. Two additional units were installed in Greenland and England. The radar frequency operated in the Ultra High Frequency (UHF) band and could track objects beyond 3,000 miles.

AN/FPS-50

This was a BMEWS program surveillance radar that used a large, fixed-antenna fence system. Two beams were projected from the antenna array. Objects passing through the lower-angled beam provided initial data and warning for the North American Air Defense Command (NORAD). Data produced when the object passed through the upper beam allowed computation of trajectories on launch and target points. The radar operated in the UHF range at 425 MHz. General Electric, Heavy Military Electronics Department, installed these systems at Clear, Alaska, and Thule, Greenland, during the early 1960s.

AN/FPS-85

This UHF, 3-D, phased-array radar was designed by Bendix for satellite tracking. Built in the early 1960s at Eglin AFB in Florida, it was the first phased-array unit in the United States. A fire destroyed the first model in 1965. A rebuilt model became operational in 1969. The southward-sloped structure contained a square transmitter face placed alongside a larger octangular receiving face. The transmitter operated at a UHF frequency of 442 MHz. The AN/FPS-85 was also used to detect submarine-launched ballistic missiles.

AN/FPS-92

This improved version of the AN/FPS-49 tracking radar was used in the BMEWS Program. Built by RCA, this radar was installed at Clear, Alaska, in the late 1960s. The radar operated in the UHF band around 425 MHz and had a range of over 3,000 miles.

AN/FPS-108 (Cobra Dane)

Cobra Dane was a large single-faced, phased-array radar built by Raytheon in the 1970s on Shemya Island in the Aleutians. As the main component of the Cobra system, the radar had the primary role of providing intelligence on Soviet test missiles fired at the Kamchatka peninsula from locations in southwestern Russia. Other components of the Cobra system included the ship-based Cobra Judy phased-array radar and the aircraft-based Cobra Ball and Cobra Eye radars. In addition to determining Soviet missile capabilities, Cobra Dane had the dual secondary role of tracking space objects and providing ballistic missile early warning. The radar antenna face of the building measured about ninety feet in diameter and contained some 16,000 elements. The L-band radar had a range of 2,000 miles and could track space objects as far as 25,000 miles away.

AN/FPS-115

Raytheon built the PAVE PAWS phased-array, missile-warning radar deployed during the early 1980s. At the four continental United States sites, the ninety foot diameter circular panel radars were mounted on two walls of a triangular-shaped pyramid structure. The antenna operated at a frequency of 420 to 450 MHz. PAVE PAWS could detect targets at ranges approaching 3,000 miles.

AN/FPS-118 (OTH-B)

Designed and built by GE Aerospace, the OTH-B radar was deployed on the east and west coasts in the 1980s. The system reflected the radar beam off the ionosphere to detect objects from ranges of 500 to nearly 2,000 miles. The transmitter arrays operated at frequencies between 5 and 28 MHz. Fixed transmitter and receiving antenna arrays were separated by a distance of 80 to 120 miles.

PARCS

The acronym, PARCS, stands for Perimeter Acquisition Radar attack Characterization System. This huge structure was built as the main sensor for the Army's Safeguard missile system that deployed north of Grand Forks, North Dakota. Upon shut down of Safeguard in 1976, the Air Force took over the huge UHF phased-array radar for use in tracking ballistic missiles and objects in space.

Federal Aviation Administration (FAA) Radars

Beginning in the late 1950s, the Civil Air Administration (predecessor to the FAA) and the DoD began to cooperate to reduce duplication. By the late 1980s most radars performing air search for the military were operated by the FAA in the joint surveillance program. Because it is a civilian agency, the FAA uses a different radar designation system.

ARSR-1

This Raytheon-built Air Route Surveillance Radar (ARSR) was used by the FAA Authority Radar beginning in 1958. It operated on a L-band frequency of 1280 to 1350 MHz with a maximum range of 200 miles.

ARSR-2

Developed by Raytheon in the 1960s as a replacement for the ARSR-1, this radar also operated in the L-band and had a similar maximum range to the ARSR-1.

ARSR-3, 3D

This Westinghouse-built search radar was used by the FAA in the Joint Surveillance System (JSS). The radar operated in the L-band at 1250 to 1350 MHz and detected targets at a distance beyond 240 miles. The D model had height-finder capability.

ARSR-4

The FAA began installing this Westinghouse-built 3-D air surveillance radar in the 1990s for the JSS system. By the late 1990s this radar will have replaced most of the 1960s-vintage AN/FPS-20 variant search radars.

COMMAND AND CONTROL SYSTEMS

Semi-Automatic Ground Environment (SAGE) System

The SAGE system was conceived by the Lincoln Laboratory at MIT in the early 1950s to receive various sensor inputs and to detect, identify, track, and provide interceptor direction against air-breathing threats to North America. The SAGE system removed Ground Control Intercept functions from several of the radar sites and reduced manpower requirements. The first SAGE control center became operational in 1958 and the system was completed in 1961. The number of SAGE centers was reduced from about two dozen in 1962 to six in 1969. These remaining six were retired in 1983. The SAGE system featured the IBMAN/FSQ-7 (Whirlwind II) large-scale, vacuum-tube, electronic, digital computer.

Because the SAGE system was vulnerable to attack from Soviet intercontinental ballistic missiles (ICBMs), the Air Force sought an alternative command and control system. In the early 1960s, some radar sites increased manning to pre-SAGE levels and manually assumed pre-SAGE Ground Control Intercept functions. The sites given this ability to perform command and control functions were called BUIC I sites. Starting in 1965, BUIC II sites became operational. BUIC II sites featured the Burroughs AN/GSA-51 computer that allowed the automatic processing of data from various radar sites. BUIC III sites became operational in the late 1960s. These sites hosted the more capable Burroughs D825 digital computer and could support operations at eleven control consoles. During the early 1970s two BUIC sites were designated to serve as backup to each of the remaining six SAGE centers. Most BUIC sites were removed from service in the mid-1970s. The BUIC center at Tyndall AFB, Florida, remained in service until the early 1980s.

JSS was an Air Force/FAA cooperative effort to provide a peacetime air surveillance and control system to replace SAGE and BUIC systems. Region Operations Control Centers (ROCCs) opened in 1983 and featured the H5118ME computer.

References

Information on the various systems was obtained from many sources. Significant sources included US Radar Survey Section 3-Ground Radar Change I (Washington, DC: National Defense Research Committee under the authority of Joint Communications Board of the Joint Chiefs of Staff, June, 1945); Eli Brookner, Radar Technology (Boston: Artech House, 1977); Bernard Blake, ed., Jane's Radar and Electronic Warfare Systems, 1994-1995, 6th ed. (Alexandria, VA: Jane's Information Group, Inc. 1994).