The Barrier Patrols: Extending the US Radar Net Out to Sea

The three main continental radar picket lines of  the Cold War

As early as 1946, the US Navy was already examining the possibility of large aircraft equipped with airborne radar as a means of extending the early warning detection times of fleets at sea. American defense planning in the early days of the Cold War assumed that whatever strike capabilities the United States had, the Soviets also had an equivalent. Since intercontinental ballistic missiles had yet to be fielded in significant numbers at the time, long range bombers like the Boeing B-29 Superfortress, its successor the B-50 Superfortress and the massive Convair B-36 Peacemaker formed the main strategic nuclear strike force of the United States. The assumptions of Soviet capabilities were validated with the unveiling of the Soviet reverse-engineered B-29, the Tupolev Tu-4 "Bull". With jet bombers on the drawing boards of US manufacturers, it was assumed that intercontinental jet bombers were also under development in the Soviet Union. Since the predominant Soviet bomber at the time was the Tu-4, its range meant that it would have to come over the North Pole to strike US targets. In November 1950, the United States and Canada agreed to build three lines of radar stations across the northern reaches of North America. The Distant Early Warning (DEW) Line formed the northernmost chain of stations that stretched from Alaska across the Canadian Arctic coast. The second line was the Mid-Canada Line that stretched across the northern parts of the Canadian provinces. The third line of radar stations was the Pinetree Line that stretched across the US-Canadian border. Several major defense studies at the time expressed concern that air refueling by the Soviets or use of bases secured in Alaska or Greenland and Iceland would allow Soviet bombers to fly around the three radar lines across Canada since they ended at the coasts. There was no doubt that there would be a need for a sea-based radar picket line in the Pacific and Atlantic, the problem was who was going to fund it and who was going to run it and on this count, the US Navy and the USAF couldn't agree on anything useful. Each service tried to push off the seaborne radar picket on the other- the Navy felt air defense as the USAF's job, so it should fund and run the system, but the USAF felt since it was sea-based, it should be the Navy's responsibility. 

Both services did come around the need to contribute to some sort of sea-based radar picket to extend the three radar lines in Alaska and Canada to prevent Soviet bombers flying around the land-based radars and approaching towards the west and east coast. The Navy's recommendation was for a combination of radar picket ships and airborne early warning (AEW) aircraft maintaining a barrier line in the mid-ocean in both the Atlantic and Pacific called SEADEW (SEAward-extension of the DEW Line). The AEW aircraft would fly racetrack orbits over the line of radar picket ships. When needed, both the picket ships and AEW aircraft could be called upon to support fleet operations. The USAF recommendation was slightly different, with AEW aircraft orbiting preset locations off the coasts and tied in by data-links to the land-based radar net. While similar in principle, the issue came down to funding as well as control. The Navy favored semi-autonomous ships and AEW aircraft that could also be used for fleet operations, offering flexibility. The USAF's Air Defense Command wanted a system that was tied into the existing radar net. Quite obviously, the Navy didn't want to fund and operate a system that was controlled by the USAF and vice versa. 

US Navy WV-2 Warning Star flies over a DER radar picket ship

Feeling that the USAF was dragging its feet and wanting a system operational that was flexible enough to support the fleet when needed, the Navy went ahead and proceeded to get the SEADEW operational during the Korean War. The Navy converted a number of destroyer escorts to destroyer escort radar (DER) vessels along with putting back into service some wartime radar picket destroyers. The Navy also procured the Lockheed WV-2 Warning Star, an AEW aircraft based on the Lockheed Super Constellation. Airborne early warning squadrons were established for the Atlantic and Pacific. The first units were multi-tasked with not just SEADEW missions but also fleet support and weather reconnaissance. VW-1 and VW-3 were assigned to the Pacific Fleet while VW-2 and VW-4 were assigned to the Atlantic Fleet. It was VW-4 that would become well known as the original "Hurricane Hunters" before the mission was transferred to the USAF. In addition to these initial Warning Star squadrons, additional units were stood up devoted primarily to flying the radar barrier patrols- VW-11, VW-13, VW-15 and a training unit were assigned the Atlantic barrier and the VW-12, VW-16, VW-16 and a maintenance unit were assigned to the Pacific barrier. The Pacific Barrier was headquartered at NAS Barbers Point in Hawaii with the barrier line running between Midway Island to the Aleutians in Alaska. The Atlantic Barrier was based at NAS Argentia in Newfoundland and ran from Newfoundland to the Azores. The DER picket ships patrolled those lines as well. Because the Navy's barrier lines were further out, they offered anywhere from 2-4 hours advance warning time of a Soviet bomber attack. 

A USAF RC-121D Warning Star with two F-104 Starfighters

Despite competing with the Navy, the USAF's AEW line complemented the Navy barrier patrols as it was closer to shore and formed a second radar line behind the SEADEW. The USAF also procured the AEW version of the Lockheed Constellation with the designation RC-121C which was based on the L-749 Constellation and the RC-121D which was based on the longer L-1049 Super Constellation. Called the Contiguous Extension, the RC-121 fleet was the USAF's first organized airborne early warning endeavor. On the West Coast, the USAF Contiguous Extension was based out of McClellan AFB near Sacramento and the East Coast operation was headquartered out of Otis AFB on Cape Cod. Since the Navy was first out of the starting blocks and was further ahead in its AEW operation, until sufficient RC-121s arrived, the USAF had to send its personnel to train with the Navy. At Otis AFB, the 551st Airborne Early Warning and Control Wing had three squadrons and the 552d AEW&C Wing at McClellan AFB also had three squadrons. In less than two years, the USAF had six squadrons of fifty AEW aircraft and over 5,000 personnel operational! 

The Lockheed WV-2/RC-121s had a combat radius of over 1,000 miles which allowed them to patrol for 16 hours before returning to base. Five officers and thirteen enlisted made up the crews, but the aircraft had the room for up to 31 personnel on longer missions needing an augmented crew. Behind the flight deck were five radar stations. There was no automation or filtering of the radar information- what was seen on the scope was the raw feed and it was up to the skill of the operator to sort through the mess to determine what was significant. Each radar station was manned in just one hour stretches to prevent fatigue and inattention. The radar system and its associated electronics had over 3,000 vacuum tubes and two enlisted in the crew were devoted just to inflight maintenance of the electronics. Most of the electronics were in the aft cabin and generated a tremendous amount of heat- it wasn't unusual for the temperature inside the cabin to hit 100F! Weather rarely scrubbed a mission- the joke was that "If you can taxi, you can fly!" Often times USAF or US Navy crews departed in such atrocious weather that they had to divert to an alternate field on return from patrol. 

The Navy's aircraft did a lot of their data interpretation aloft as they operated on the barrier lines autonomously and would radio any findings by HF. The USAF's aircraft were tied in by datalinks to the SAGE (Semi-Automatic Ground Environment) system used by NORAD and operators ashore would sort through the radar data. Despite this level of automation, USAF RC-121s were staffed with full crews in the event the data links went down as well as have onsite personnel who could interpret radar data without waiting for the SAGE operators ashore. The USAF's RC-121s were later re-designated EC-121s and they flew their patrols around 15,000 feet. The Navy's WV-2s flew their patrols at lower altitudes between 5,000 to 8,000 feet. The strategic imperative of these radar missions was such that spare aircraft and crew were often prepared to be able to depart at a moment's notice should an aircraft en route to its patrol area had technical issues- and those were common given the cantankerous nature of the Constellation's Wright R-3350 engines. While the US Navy did its best to keep its barrier lines fully covered, the USAF settled on randomly patrolling parts of its Contiguous Extension, and more so as the main threat to the United States shifted from bombers to ICBMs. Each coast had nine patrol stations, odd numbered 1 through 9 in the Pacific with 1 near the Aleutians and 9 off the coast of Baja California. In the Atlantic, even numbered patrol stations 2 through 8 in the Atlantic were used. Each patrol station was a 100 mile racetrack orbit. In low tension periods, USAF EC-121s would only operated on one station and the station was randomly decided, the crew finding out which station once they had taken off. During periods of higher tension, more stations would be active. During such periods, all of the USAF stations were operated on both coasts and this meant every four hours an EC-121 departed from McClellan AFB and Otis AFB. 

Despite the maximum effort expended by the US Navy and the USAF, several air defense exercises in the late 1950s showed the barrier patrols weren't as effective as hoped. Electronic failures were the most common cause of a degraded mission with engine problems a distant second. At one point in 1959 the USAF's Air Defense Command had gotten so frustrated with electronic and engine issues with the EC-121 fleet a proposal was floated to transfer the Contiguous Extension operation to the US Navy! Fortunately cooler heads prevailed and the USAF wasn't allowed to give its AEW experience. But the strain on men, aircraft, and budgets began to take its toll on both services. In 1960 the US Navy disestablished some Pacific Fleet squadrons, merging them into other units. During the FY1961 budget debate, questions arose as to the wisdom of continued funding of the barrier patrols in light of the shift in Soviet threat from bombers to ICBMs. The USAF and the Navy had other funding priorities and gradually, both the Navy and USAF barrier patrols were wound down. The Atlantic barrier line was pushed further east centered on a Greenland-Iceland-UK axis with the base of patrols at NAS Keflavik in Iceland. On 8 September 1965, the last AEW barrier mission was flown by a Navy EC-121P (in 1962 the Navy and USAF went to a unified designation system) out of Argentia, ending 10 years of barrier patrols over the Atlantic and Pacific by both the USAF and US Navy. 

So was it worth it? That's a tough question. In the 1950s the bomber threat was still the main nuclear threat and certainly there was deterrent value in the barrier patrols as potential adversaries were put on notice the great lengths the US military was taking to insure vigilance. Perhaps more importantly, it gave both the US Navy and USAF practical airborne early warning experience that laid the foundations for modern aircraft like the Grumman E-2 Hawkeye and the Boeing E-3 Sentry. 

Source: AWACS and Hawkeyes: The Complete History of Airborne Early Warning Aircraft by Edwin Leigh Armistead. Motorbooks International, 2002, pp 21-40. Photos: Wikipedia

The CIM-10/IM-99 Bomarc was one of the first very long range surface to air missiles to go into service, becoming operational with NORAD for the air defense of North America in 1959. Housed in a rectangular semi-hardened shelter, on receiving the launch order the shelter's roof would slide open and the Bomarc would be raised into the vertical launch position. An Aerojet General LR59 liquid-fueled booster rocket would accelerate the Bomarc to over Mach 2.5 and 60,000 feet when the twin Marquardt RJ43 ramjets took over to propel the missile to over 200 miles out from launch where its 10-kiloton W40 nuclear warhead would destroy the target bombers.

The booster rocket of the missile used hypergolic fuels- red fuming nitric acid as an oxidant and aniline fuel that would spontaneously ignite when mixed. The fuels were stored on the missile for 90 days at a time. When a launch order was received, a helium tank on the missile would be pressurized to provide propellant tank pressurization for the booster rocket. It would take 15 seconds to pressurize the tank, during which time the Bomarc was raised to the vertical position for launch. At the end of each 90 day period, the missile would have to be defueled, decontaminated and then refueled. Pressurized helium would be used to empty the tanks to defuel them as well as in the refueling procedure.

On 7 June 1960 the firefighting department of Fort Dix and McGuire AFB, New Jersey received an emergency call that a fire had broken out in Bomarc Shelter #204. The missile in that shelter was nuclear tipped and the failure of a helium tank set up a pressure shockwave that ruptured the booster rocket propellant tanks, spilling the hypergolic fuels and starting a fire. The fire then heated the remaining fuel in the missile, causing an explosion. Fortunately the shelter roof doors were closed and took the brunt of the propellant explosion, but the steel roof and blast doors were still blown off the shelter and the fierce fire burned for 45 minutes. The missile and launch equipment were destroyed and the fire was so intense the steel structural beams of the launch shelter sagged from partially melting.

Fortunately the hardened shelter design contained most of the explosion and debris and the adjoining launch shelters were undamaged. Water had to be pumped on the remains of the shelter and missile through the night before it cooled down enough for radiation safety teams from the Atomic Energy Commission and the USAF to survey the damage. As the fire had to burned, the structure of the missile melted and the nuclear warhead fell right into the fire and was itself partially melted. Careful study of the remains of the warhead showed that between 2 to 11 oz of plutonium were lost but the tritium tank that held the heavy hydrogen isotope to trigger the nuclear reaction was intact.

The plutonium caused radiation counts inside the remains of the shelter to soar to 2 million counts per minute as the salvage teams had to wear protective gear. What was left of the floor and shelter were sprayed with a special thick paint that absorbed the radiation (thankfully there was no high energy gamma radiation from detonation of the warhead) and four inches of concrete were poured on the surrounding area until detected radiation counts were zero. The site remained fenced off until the Bomarc missiles were decommissioned in 1972. In 2004 the USAF had the site demolished and had 20 feet of soil surrounding the shelter excavated. The soil and the debris were shipped out to a nuclear waste repository in Utah.

Source: Airpower, September 2004, Volume 34, No. 9. "Nuclear Nightmare Almost" by Dr. Richard V. Porcelli, p13.

Though notoriously short-legged and cursed with less-than-ideal handling, the Douglas F4D Skyray was famous for its climb performance. In 1958, Marine Corps Maj. Edward N. LeFaivre shattered five world records in the time-to-height category by flying a Skyray from NAS Point Mugu to 49,212 feet in only 2 minutes and 36 seconds. Designed to intercept high flying bombers attacking a carrier battle group, the Skyray's hot climbing performance made it the only Navy fighter to be formally assigned NORAD air defense duties as a land-based interceptor.

On 2 May 1958 All-Weather Fighter Squadron THREE (VFAW-3) was formed at NAS North Island, San Diego to stand air defense alert for the southern US West Coast. Wearing the tailcode "PA" and an attractive blue spine and tail with yellow stars, NORAD's shield was in the squadron's North Island hangars but not on the aircraft themselves. Armed with four 19-shot rocket pods and later Sidewinder missiles, VFAW-3's Skyrays were a leap on capability over the F9F Panthers and F3D Skynights that were originally proposed by the US Navy to serve NORAD alert on the US West Coast.

Led by 23-victory World War II ace Eugene Valencia, VFAW-3 would twice win NORAD's highest honors for efficiency and readiness, topping all other USAF and Canadian air defense units.

Source: Combat Aircraft Monthly, January 2010. "US Navy Fighters of the Fifties: F4D Skyray" by LCDR Rick Burgess USN (Ret), p70-77.

In October 1961 NORAD mounted its largest-ever air defense test, Exercise Skyshield. In order to be as fully realistic as possible, the Strategic Air Command's Boeing B-47 Stratojet and B-52 Stratofortress units would try to penetrate NORAD's radar and fighter defenses. In addition, No. 27 and No. 83 Squadrons of the Royal Air Force's Bomber Command each sent four Avro Vulcans to participate in Skyshield. No. 27 Squadron's four Vulcans were deployed to Kindley AFB, Bermuda, to penetrate the defense net from the south and No. 83 Squadron's four Vulcans were deployed to RAF Lossiemouth in Scotland to penetrate from the north.

On 14 October Exercise Skyshield began in earnest with the incoming bombers taking off. The northern attack began with the B-47s coming in as low as 500 feet to jam out the ground radars. Behind the Stratojets came the B-52s at 35,000 to 42,000 feet supported by jamming by EB-57 Canberras. And behind the Stratofortresses came the Vulcans at 56,000 feet. The heavy jamming was so effective that only the first Vulcan detected the radar of an F-101 Voodoo. Although NORAD scrambled many fighters, they concentrated on the B-52s and by the time the Vulcans arrived, they lacked the fuel to climb to 56,000 feet. No. 83 Squadron's Vulcans reached their target points all unscathed (which was to land at a base in Newfoundland).

The southern wave followed and used similar tactics only this time the four Vulcans from No. 27 Squadron were on their own. The four Vulcans approached the US Northeast on a broad front with their systems in full ECM and jamming. Fifty miles from the coast as defending F-102 Delta Daggers were scrambling, the southernmost Vulcan turned north and flew behind the other three Vulcans and was effectively masked by the onboard jamming of those three bombers. While the Delta Daggers swarmed the other three Vulcans, the fourth Vulcan penetrated unscathed and undetected to reach its target (which was to land at Plattsburgh AFB in upstate New York).

Source: Vulcan Units of the Cold War by Andrew Brookes, Osprey Combat Aircraft #72. Osprey Publishing, 2009, p21.