Atlas F Site 577-4 Missile Silo, Cache Oklahoma

Atlas F Site 577-4 was one of the twelve SM-65F Atlas intercontinental ballistic missile launch complexes assigned to the 577th Strategic Missile Squadron at Altus Air Force Base, Oklahoma. The site was the squadron's Site 4, located in Comanche County near Cache in southwestern Oklahoma.

The site belonged to the 11th Bombardment Wing, which was redesignated the 11th Strategic Aerospace Wing on 1962-04-01, and to the 577th Strategic Missile Squadron, the Altus Atlas F missile unit. Atlas F launch complexes were self-contained vertical silo sites with an underground launch-control center at the complex itself rather than Minuteman-style unmanned launch facilities controlled from a separate remote LCC.

Site 577-4 is inactive and decommissioned as a military installation. Construction at the site began on 1960-05-09, the site was turned over to the Air Force on 1961-08-23, and the Altus Atlas F missile force became operational in early October 1962. The site remained part of the operational 577th Strategic Missile Squadron until the Atlas F weapon system was removed from service in 1965. Site 577-4 was decommissioned on 1965-03-25, the same date on which the 577th Strategic Missile Squadron was inactivated.

Its assigned operational missile was General Dynamics Atlas missile 50F, serial number 61-2536, Air Force tail number 536. The missile was accepted on 1962-02-20 and delivered on 1962-03-10. Unlike some Atlas F missiles that were scrapped after their ICBM service, Atlas 50F later received a second career as a space-launch vehicle. It was launched successfully from Vandenberg Air Force Base Space Launch Complex 3 West on 1977-12-08 with the classified OPS 8781 / NOSS-2 payload.

The former launch complex is now non-federal, private property. No public reuse, museum operation, or authorized visitor program was found for Site 577-4. The site should therefore be treated as a decommissioned former missile complex on private land with no public access.

Location, Landscape, and Site Description

Site 577-4 occupies a rural setting west-southwest of Cache, Oklahoma, near the Wichita Mountains region and within the broader southwestern Oklahoma missile field that surrounded Altus Air Force Base. The site was one of the twelve Altus Atlas F launch complexes placed in a broad ring around the base. Official Altus AFB history states that the 577th Missile Squadron activated in 1961 to operate twelve Atlas F missile sites within a forty-mile radius of Altus. That dispersal pattern was a central element of first-generation ICBM basing. It separated the launch complexes so that one attacking weapon could not destroy the entire missile force, while keeping the sites close enough to Altus for logistics, security response, maintenance, communications, and command administration.

The Cache area provided the Air Force with the kind of landscape it needed for an Atlas F site: open rural land, relatively low surrounding population density, road access, and enough separation from the parent base and the other launch complexes to support a dispersed nuclear-alert posture. The site was not simply a small surface pad or a marker in a field. Atlas F launch complexes were large underground engineered facilities that required deep excavation, reinforced concrete, silo doors, an elevator-launcher, utility systems, propellant systems, crew facilities, communications, fencing, and surface support structures.

Atlas F was the vertical-silo member of the operational Atlas family. A typical Atlas F complex included a deep cylindrical silo, a large elevator-launcher, two heavy silo doors, a below-grade launch-control center, connecting passages, environmental-control equipment, power generation and distribution equipment, propellant and liquid-oxygen support systems, antenna and communications equipment, access roads, fencing, and a controlled surface compound. The Association of Air Force Missileers describes the Atlas F as housed in a vertical silo with an adjoining control center, hardened to 100 psi overpressure, and raised to ground level by a large silo elevator before launch. The Western Oklahoma Historical Society describes the Altus-area Atlas F silos as deep, heavily reinforced concrete structures with a connected launch-control center where five-person crews served around the clock.

Strategic and Cold War Context

Site 577-4 existed because the United States was rapidly building a credible land-based nuclear deterrent during the early Cold War. The Atlas missile family was the first operational American intercontinental ballistic missile system. Atlas was developed in an era when Strategic Air Command still relied heavily on bomber aircraft, but national strategy increasingly required missiles that could reach intercontinental targets from the United States, remain on alert, and complicate Soviet attack planning.

The Atlas F represented the most survivable operational Atlas basing concept. Atlas D used launch complexes with exposed gantry-type arrangements, and Atlas E stored the missile horizontally in a semi-hardened coffin launcher. Atlas F placed the missile upright in an underground silo. It still used liquid propulsion and therefore retained operational limitations that later solid-fueled missiles avoided, but the hardened silo made the missile more survivable and reduced its exposure before launch.

The missile used RP-1 kerosene fuel and liquid oxygen oxidizer. RP-1 could remain aboard the missile while it sat on alert, but liquid oxygen had to be loaded during the launch countdown. The missile would then be raised on the silo elevator before launch. This was more complex and slower than the near-instant readiness of later Minuteman missiles, but in 1962 the Atlas F force was a major step toward hardened, dispersed, land-based deterrence.

The Altus missile field became operational at a historically significant moment. Official Altus AFB chronology states that the 577th Missile Squadron's Atlas F sites became operational on 1962-10-10, while USAF unit-history material use 1962-10-09t. Either way, the field became operational immediately before the Cuban Missile Crisis reached its most dangerous phase. During that crisis, the operational Altus Atlas F force formed part of the United States' strategic nuclear-alert posture.

Construction and Activation

Construction of the Altus Atlas F missile field began under the larger national program to field hardened ICBM sites in the central United States. Official Altus AFB chronology states that construction began on the first of twelve Atlas F missile sites in the area around Altus AFB on 1960-05-01. The Western Oklahoma Historical Society places the ceremonial groundbreaking for the Altus-area missile sites on 1960-05-20 at Altus AFB. These events marked the beginning of a fast, large, and technically demanding construction program spread across southwestern Oklahoma and one nearby Texas site.

Construction at Site 577-4 began on 1960-05-09. The site was listed as Corps of Engineers Construction Site Number 3 and Air Force Operational Site Number 4. Building an Atlas F complex required excavation of the silo shaft, placement of heavily reinforced concrete, installation of the steel launch-support structure, construction of the adjoining underground control center and connecting passages, installation of mechanical and electrical systems, installation of propellant-support systems, construction of surface support features, and integration of the launch equipment with the Atlas missile and Strategic Air Command procedures.

The site was turned over to the Air Force on 1961-08-23. Turnover did not necessarily mean that the site immediately stood nuclear alert. It meant the facility had reached the stage at which Air Force and contractor organizations could continue with equipment checkout, missile acceptance, training, certification, and operational readiness. The site's assigned missile, Atlas 50F, was accepted on 1962-02-20 and delivered on 1962-03-10. The Altus Atlas F force then reached operational status in October 1962, just as the Cuban Missile Crisis placed Strategic Air Command on heightened alert.

The speed of the construction program reflected the strategic urgency of the time. The Atlas F sites were built before the United States had fully transitioned to solid-fueled ICBMs. They were expensive, complex, and labor-intensive, but they gave Strategic Air Command a hardened and dispersed missile capability during the narrow period between early experimental ICBM deployment and the more durable Minuteman era.

Missile System and Technical Role

Site 577-4 housed the SM-65F Atlas, later commonly identified as HGM-16F after the 1962 missile-designation changes. The Atlas F was a one-and-one-half-stage, liquid-fueled ICBM built by Convair/General Dynamics. It used a booster-and-sustainer arrangement and burned RP-1 fuel with liquid oxygen. The Atlas airframe depended on internal pressurization for structural rigidity, which made the missile operationally demanding compared with later solid-fueled ICBMs.

The Atlas F differed from earlier Atlas models primarily in its hardened vertical silo-lift launch system. The missile was stored vertically below ground on a large elevator. During a launch sequence, liquid oxygen would be loaded, the silo doors would open, the missile and launcher would be raised to the surface, and the missile would launch from the raised position. This minimized exposure compared with earlier surface or coffin-launch systems, but it did not eliminate the need for a complex countdown and propellant-handling process.

The missile carried a public-source W-38 thermonuclear warhead in an Avco Mark 4 reentry vehicle. The National Air and Space Museum describes the Mark 4 reentry vehicle as used on Atlas E/F and Titan I ICBMs in the early 1960s and carrying a W-38 nuclear warhead with a yield of about 3.75 megatons.

The site's technical role was to keep one Atlas F missile ready for Strategic Air Command alert. Unlike Minuteman launch facilities, which were normally unmanned and remotely controlled from geographically separate launch-control centers, an Atlas F complex included its launch-control function at the missile site. Crews, maintenance technicians, security personnel, communications specialists, and contractor support all interacted with the site during its service life. A five-person missile combat crew could serve inside the complex while the missile remained on alert, supported by maintenance and security activity above and below ground.

Operational History

The 577th Strategic Missile Squadron operated the Altus Atlas F field from 1961 until 1965. The squadron was created to operate a dispersed set of twelve Atlas F launch sites around Altus Air Force Base. Eleven were in Oklahoma and one was near the Texas border. Site 577-4 was the Cache site in that network.

The 577th SMS stood up at a time when Strategic Air Command was accelerating the deployment of hardened ICBM forces. Official Altus AFB chronology records that the squadron activated on 1961-06-01 to operate the twelve Atlas F sites. USAF unit-history material records SAC turnover and operational status on 1962-10-09, while official Altus public history gives 1962-10-10 as the date the squadron became operational.

Operational life at Site 577-4 was defined by alert duty, security, maintenance, inspections, communications reliability, propellant safety, and crew readiness. The Atlas F was more protected than earlier Atlas models, but it remained a liquid-fueled missile. Site personnel and supporting organizations had to maintain the missile, ground support equipment, silo systems, propellant systems, power systems, environmental controls, communications equipment, and security systems. Readiness depended not only on the missile but also on the entire complex functioning as a hardened launch system.

The Cuban Missile Crisis occurred almost immediately after the Altus Atlas F force reached operational status. During the crisis, Strategic Air Command moved to a heightened alert posture. Squadron-level history records that the operational Atlas F sites were part of this alert structure. Site 577-4's significance therefore lies not in a known individual launch or accident during the crisis, but in being one of the newly operational hardened Atlas F sites available to SAC at the moment when the Cold War nuclear confrontation became most acute.

The site served for only a short period because technology moved rapidly. By the time the Atlas F field was fully operational, the United States was already deploying solid-fueled Minuteman missiles. Minuteman offered faster reaction, simpler alert operations, lower maintenance burden, and better suitability for long-term hardened-silo deployment. Secretary of Defense Robert McNamara announced the Atlas phaseout in 1964, and the 577th SMS stood down the following year.

The assigned missile, Atlas 50F / serial number 61-2536 / tail number 536, also had a notable post-ICBM career. After the operational Atlas F force was retired, Atlas 50F was not simply scrapped. It was launched successfully from Vandenberg AFB's SLC-3W on 1977-12-08 with the OPS 8781 / NOSS-2 payload, a mission considered classified by the Air Force at the time.

Deactivation and Disposal

Atlas F was overtaken by the rapid deployment of solid-fueled Minuteman ICBMs and by the high maintenance burden of the liquid-fueled Atlas system. Secretary of Defense Robert McNamara announced the phaseout of the remaining Atlas ICBMs in 1964, and the Altus Atlas F force was removed from service the following year.

Site 577-4 was decommissioned on 1965-03-25. That date is also the inactivation date for the 577th Strategic Missile Squadron. Decommissioning meant the site no longer served as an operational ICBM launch complex. The missile was removed from strategic-alert status, the squadron was inactivated, and the property entered the broader pattern of surplus former Atlas F sites that were later transferred out of active Air Force use.

Site 577-4's closure occurred before the later Strategic Arms Reduction Treaty inspection and silo-elimination regimes that affected many Minuteman and Peacekeeper launch facilities. Atlas F sites such as 577-4 were retired as part of an early Cold War weapons-system phaseout rather than as START-era treaty-demolition cases. As a result, the site's later physical condition depended on surplus disposal, private reuse, environmental cleanup, and local land use rather than on the later standardized treaty procedures for destroying modern ICBM silos.

The former site did enter the federal environmental-restoration record. The USACE FUDS inventory lists CACHE, ATLAS MISSILE NO. 4, K06OK0404, with both BD/DR and HTRW project entries. The U.S. General Accounting Office's 2001 Oklahoma FUDS table lists ATLAS MISSILE NO. 4, K06OK0404, Comanche County, as eligible with hazards and eligible cleanup projects. ProPublica's DERP-derived Bombs in Your Backyard dataset lists ATLAS MISSILE NO. 4 at Cache, Comanche County, with two sites and Response Complete status. A Defense Environmental Restoration Program table also lists ATLAS MISSILE NO. 4 / OK69799F640600 among FUDS properties that achieved final Response Complete status before fiscal year 2022. These records show that the former missile property remained part of the long afterlife of Cold War infrastructure after its operational mission ended.

Current Status and Site Use

Site 577-4 is a decommissioned former Atlas F launch complex on private property near Cache, Oklahoma. It is not an active military installation and no public museum, public tour operation, or official interpretive program was found for the site. The site should be treated as private property with no public access unless an owner or lawful authority explicitly grants permission.

Public aerial imagery shows the former compound in a rural setting. The site appears to retain a recognizable launch-complex footprint, including the former access and surface compound area.

Chronology

• 1960-01 Public announcements identified Altus AFB as the future hub for twelve Atlas F missile sites in southwestern Oklahoma and nearby Texas.
• 1960-05-01 Official Altus AFB chronology states that construction began on the first of twelve Atlas F missile sites around Altus AFB.
• 1960-05-09 Construction began at Atlas F Site 577-4 near Cache, Oklahoma.
• 1960-05-20 A ceremonial groundbreaking for the Altus-area Atlas missile sites was held at Altus AFB.
• 1961-06-01 The 577th Missile Squadron activated at Altus AFB to operate twelve Atlas F launch sites.
• 1961-08-23 Site 577-4 was turned over to the Air Force.
• 1962-02-20 Atlas missile 50F / serial number 61-2536 / tail number 536 was accepted.
• 1962-03-10 Atlas missile 50F was delivered for the Altus operational ICBM mission.
• 1962-04-01 The 11th Bombardment Wing was redesignated the 11th Strategic Aerospace Wing.
• 1962-08 USAF unit-history material records the first Series F Atlas ICBM at the 577th SMS placed on alert early in the month.
• 1962-10-09 USAF unit-history material lists SAC turnover and operational status for the 577th SMS missile force.
• 1962-10-10 Official Altus AFB and Oklahoma historical chronology sources state that the Atlas F missile silos became operational.
• 1962-10 The 577th SMS Atlas F sites were on heightened alert during the Cuban Missile Crisis.
• 1964-05-14 A propellant-loading explosion destroyed squadron Site 577-6 near Frederick, Oklahoma; this did not occur at Site 577-4.
• 1965-03-25 Site 577-4 was decommissioned and the 577th Strategic Missile Squadron was inactivated.
• 1977-12-08 The former Site 577-4 missile, Atlas 50F, launched successfully from Vandenberg AFB SLC-3W carrying OPS 8781 / NOSS-2.
• 2001 GAO listed ATLAS MISSILE NO. 4, K06OK0404, Comanche County, as eligible for potential inclusion in the FUDS cleanup program with hazards and eligible projects.
• 2015-09-30 The USACE FUDS Oklahoma inventory listed CACHE, ATLAS MISSILE NO. 4, K06OK0404, with BD/DR and HTRW entries.
• 2017 ProPublica's DERP-based Bombs in Your Backyard dataset listed ATLAS MISSILE NO. 4 at Cache, Comanche County, with Response Complete status.
• 2022 A Defense Environmental Restoration Program table listed ATLAS MISSILE NO. 4 / OK69799F640600 among FUDS properties that achieved final Response Complete before fiscal year 2022.

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