and
BMEWS coverage The site was purchased by the
Department of the Interior in 1949 for use as a gunnery range for
Ladd Field. The site became
Clear Air Force Auxiliary Field. In May 1958 total costs for the planned
BMEWS Site I at Thule and BMEWS Site II at Clear were estimated at ~$800 million. In October 1958 they were both estimated to be completed in September 1960. An additional area was appropriated for the Clear site. Clear is served by a spur of the
Alaska Railroad, being about south of
Nenana and the
Mears Memorial Bridge over the
Tanana River that flows past Clear. This has transported coal for the
power station and heavy equipment.
Clear Missile Early Warning Station Clear Missile Early Warning Station construction began in August 1958 with 700 workers—i.e., a "construction" camp was being erected in September 1958 by "Patti-McDonald and Morrison-Knudsen" next to the railroad (for $1.7 million, 40,000 ft of railroad were moved by 1959.) Groundbreaking for radar structures was May 1959 ("Baker and Ford built a transmitter and computer building; a heat dissipation system; a radar transmitter building; wells and pumphouses; a fire station; and utilities") and the AN/FPS-50 pedestals were complete by June 2, 1959. In 1959 after the original
White Alice Communications System contract, "the next segment of WACS... was series of TD-2 microwave installations to support... two routes [that] linked the Ballistic Missile Early Warning Site (BMEWS) at Clear AFB... one going down the southeast coast (the A route) to the
Ketchikan-Seattle submarine cable*, and the other, going east to the Canada–US border (B Route) through Canada, down to the lower 48 which was Clear's
Rearward Communications System to
Murphy Dome (A Route) and the
Gold King Creek AFS (B Route) with data for the
Ent AFB CC&DF. Three
GE AN/FPS-50 Radar Sets were installed with antenna reflectors that each weigh . The "Building Two" middle transmitter building had the
radar control room and room with the
Sylvania AN/FSQ-28 Missile Impact Predictor Set. The "
Clear Msl Early Warning Stn,
Nenana, AK" was assigned to
Hanscom Field, Massachusetts, on April 1, 1961, and BMEWS Site II was completed July 1, 1961 (the date of
IOC--
Full operational capability was declared three months later.) Clear transferred to
Air Defense Command in November 1961. By mid-1962, BMEWS "quick fixes" for
ECCM had been installed at Thule and Clear and by June 30, 1962,
Ent AFB integration of BMEWS and
SPADATS data was completed. On July 31, 1962, NORAD recommended a tracking radar at Clear to close the BMEWS gap with Thule for low-angle missiles (compared with those with the 15-65 degree angle for which BMEWS was designed) (North Dakota's
Cavalier AFS radar built in 1975 currently monitors for
Hudson Bay launches.)
Missile warning operations Detachment 2 of the
71st Missile Warning Wing was responsible for operations by civilian contractor personnel until 1964, when Air Force personnel began permanently manning the Tactical Operations Room (TOR). In 1964, the
Good Friday earthquake struck, and Clear was unable to perform its mission for six minutes. In 1966, the last of the five BMEWS tracking radars was installed, an
RCA AN/FPS-92 Radar Set with an diameter antenna housed in a diameter
radome. The FPS-92 was an improved
AN/FPS-49 Radar Set variant with radome blocks having two high-density 1 millimeter thick skins that cover a 15 centimeter thick Kraft-paper core (total of 1,646 hexagonal and pentagonal blocks (the hexagonal blocks were "66-inch panels".) The completion of the FPS-92 raised the final construction price of the missile warning system at Clear to $300 million. $62 million of this figure had been spent by the Alaska District of the Corps of Engineers.) Clear provided emergency shelter for 216 flood refugees during August 1967, the same year many "temporary" buildings were replaced. Personnel at the installation subsequently provided measurements for a
University of Alaska experiment which injected
sulfur hexafluoride into the
upper atmosphere to see if the
Aurora Borealis could be affected. Clear had
Bomb Alarm System equipment installed by the time the BAS was accepted on 10 February 1961. The BAS was deactivated in 1970. In 1975, the
Secretary of Defense told Congress that Clear Air Force Station would be closed when the
Shemya Island and
Beale AFB radars became operational. After a Thule radome fire, Clear's FPS-92 radome was replaced in 1981 by first disassembling the tracker, constructing the new radome, and reconstructing the FPS-92. Clear's 1st all-female crew pulled its 1st shift on February 28, 1986 (the 1st female, Lt. Anderson was assigned in 1973.) Beginning in 1987,
ITT operated and maintained the Clear BMEWS under a USAF Space Command contract and in the 1990s, the
Southwest Research Institute upgraded Clear's pulse modulator for the transmitter final-stage power amplifier.
Phased array radar On April 16, 1998, groundbreaking for installing 1987 AN/FPS-115
PAVE PAWS components
from Texas (e.g., the array elements) was held at Clear for the more advanced Raytheon
AN/FPS-120 with 2500 "solid state transmitter" modules. On December 15, 2000, the FPS-50 and −92 transmissions ceased (all of the
Arecibo Observatory's
Litton L-5773
klystrons were obtained as surplus from Clear's decommissioned BMEWS transmitters.) Clear's FPS-120 began 24-hour operations when Clear's
SSPARS Site (separate from the BMEWS site) had
Initial Operational Capability on January 31, 2001; the date the entire SSPARS became operational (SSPARS sites were modified in the
Early Warning Radar Service Life Extension Program.) On August 30, 2006, after a transition that began in 2001,
the ANG's 213th Space Warning Squadron took on the early warning/space surveillance mission.
BAE Systems began a 2007 contract for SSPARS maintenance, and the Clear FPS-120 was subsequently upgraded to an
AN/FPS-132 Upgraded Early Warning Radar (UEWR) by
Boeing Integrated Defense Systems "featuring processor and software improvements to enhance capability."
Long Range Discrimination Radar was being tested at the base in 2022. == Based units ==