Atlas F Site 577-11 Missile Silo, Willow Oklahoma

Atlas F Site 577-11 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 11 and was located near Willow in Greer County, 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 Atlas F missile unit assigned to Altus AFB. Atlas F launch complexes were self-contained vertical-silo sites with their own launch-control and support structures, rather than Minuteman-style unmanned launch facilities controlled from a separate remote launch control center.

Site 577-11 is inactive and decommissioned as a military missile installation. Construction at the site began on 1960-07-01, the site was turned over to the Air Force on 1961-10-04, and the Altus Atlas F missile force became operational in 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 577-11 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 87F, serial number 61-2573, Air Force tail number 573. The missile as accepted on 1963-03-21 and delivered on 1963-04-19.

After leaving operational service, the missile was used in the successful NOAA-C / NOAA-7 launch on 1981-06-23. The Cape Canaveral Space Force Museum's SLC-3W history lists 1981-06-23 as the last Atlas F launch from that complex.

The former missile property later entered the Formerly Used Defense Sites environmental record as ATLAS MISSILE NO. 11 / K06OK0411. The 2015 U.S. Army Corps of Engineers FUDS inventory lists the property at Willow, Greer County, Oklahoma, with Hazardous, Toxic, and Radioactive Waste and Building Demolition / Debris Removal project entries. ProPublica's DERP-based summary lists ATLAS MISSILE NO. 11 at Willow, Greer County, as Response Complete. The site should be treated as a decommissioned former missile complex on non-public property with no public access.

Location, Landscape, and Site Description

Site 577-11 is in rural southwestern Oklahoma near Willow, north-northwest of Altus Air Force Base. The surrounding landscape is open agricultural and ranch country, with broad fields, county roads, and low relief. That physical setting was typical of the Altus Atlas F field. Strategic Air Command wanted dispersed single-missile launch complexes that were remote enough to reduce the vulnerability of the squadron to a single attack on the parent base, but still close enough for maintenance, security, communications, engineering, and logistics support from Altus AFB.

The site's location in Greer County also reflects the wide geographic spread of the Altus missile field. USAF unit-history material explains that the twelve Altus Atlas F launcher locations were distributed around or near Lone Wolf, Hobart, Snyder, Cache, Manitou, Frederick, Creta, Hollis, Russell, Willow, and Fargo, Texas. That network required land acquisition across several counties and turned scattered farm and ranch parcels into hardened missile complexes.

Site 577-11 was not a surface launch pad. It was an Atlas F vertical-silo launch complex built around a deep reinforced-concrete underground silo, an elevator launcher, heavy silo doors, an underground launch-control and equipment area, utility rooms, electrical and environmental-control systems, communications equipment, propellant and liquid-oxygen handling systems, security fencing, surface support features, and access roads. The missile stood vertically inside the underground silo. During a launch sequence, it would be raised to the surface and launched from above ground, rather than fired from within the closed silo.

Satellite photographs (see below) show a compact former Atlas F compound in a rural agricultural landscape. Operational-era photographs (photos 1 and 2) of Site 11 during a propellant-loading exercise, with the Atlas missile raised on the elevator launcher and vapor visible around the pad. Those images are important because they show how different an Atlas F site was from later solid-fueled Minuteman silos: the missile had to emerge from the silo and undergo liquid-oxygen operations before launch.

Strategic and Cold War Context

Site 577-11 existed because the United States was rapidly building a survivable land-based nuclear deterrent during the early 1960s. Atlas was the first operational U.S. intercontinental ballistic missile, and official Air Force and National Park Service sources describe it as the first operational ICBM fielded by the Air Force. The Atlas program was a first-generation crash effort to place long-range ballistic missiles on alert before later, more maintainable systems such as Titan II and Minuteman could fully mature.

Atlas F was the most protected operational version of the Atlas missile. Earlier Atlas D and Atlas E systems used surface, gantry, or horizontal coffin-launcher arrangements. The F model placed a single missile upright inside an underground silo. That design gave the missile protection while it was not exposed, provided a harder target than aboveground launchers, and placed each missile in a separated one-missile complex.

The system was powerful but transitional. Atlas F was liquid-fueled. Its RP-1 fuel could be kept aboard the missile while it was on alert, but liquid oxygen had to be loaded during the countdown. The Atlas airframe also depended on internal pressure for structural rigidity. The site therefore represented both an advance in survivability and a maintenance-intensive stage in ICBM development. Later solid-fueled Minuteman sites would be simpler to keep on alert, faster to launch, and less dependent on hazardous propellant-loading activity at the launch site.

Site 577-11 entered the operational force at an especially tense moment. Official Altus AFB chronology states that the 577th Missile Squadron activated on 1961-06-01 to operate twelve Atlas F missile sites within a forty-mile radius of Altus and that the squadron became operational on 1962-10-10. USAF unit-history material lists SAC turnover and operational status on 1962-10-09. The one-day difference is a source conflict between two public Air Force-derived summaries, but both place the Altus Atlas F force on operational status immediately before the Cuban Missile Crisis. During that crisis, the 577th SMS sites were part of Strategic Air Command's nuclear alert posture.

Construction and Activation

Construction of the Altus Atlas F missile field began as part of the nationwide program to deploy hardened ICBM launchers at dispersed inland sites. Official Altus AFB chronology states that construction began on the first of the twelve Atlas F missile sites around Altus on 1960-05-01. USAF unit-history material records that the Corps of Engineers, Tulsa District awarded the basic construction contract for the Altus Atlas F field to Morrison-Knudsen and Hardeman and Associates, with a combined bid of just over $20.9 million.

The same USAF unit-history material records that the twelve launcher locations were sited around the region and that land acquisition required the Tulsa District's Real Estate Division to file condemnation suits against 477 landowners in six counties to acquire 12,879 acres. That information is important to understanding Site 577-11 because the Willow site was not an isolated construction job; it was one parcel in a large, synchronized missile-field construction program.

Site 577-11 was Corps of Engineers Construction Site Number 9 and Air Force Operational Site Number 11. Construction at the Willow site began on 1960-07-01. The work required excavation of the deep silo, placement of heavily reinforced concrete, installation of the elevator launcher and silo doors, construction of the underground control and support areas, and installation of liquid-oxygen, RP-1, power, communications, ventilation, security, and environmental-control systems.

The site was turned over to the Air Force on 1961-10-04. Turnover did not mean the launch complex instantly became part of a certified operational force. First-generation ICBM activation required overlapping stages of construction completion, equipment checkout, missile delivery, site acceptance, crew training, propellant-system testing, communications integration, and SAC operational certification. The Altus Atlas F force reached operational status in October 1962, immediately before the Cuban Missile Crisis.

Missile System and Technical Role

Site 577-11 was built for the SM-65F Atlas, the final operational Atlas ICBM variant. The Atlas F was stored vertically underground and raised to the surface before launch. The silo gave the missile protection while it was on alert, but the missile was not a cold-launched or hot-launched weapon fired from within the closed silo. The elevator-launcher system raised the missile to the surface before launch.

Public Air Force and museum sources describe Atlas as a powerful liquid-fueled missile with a range of more than 6,300 miles. National Park Service material describes Atlas F as an 82-foot missile held in a blast-proof silo-lift configuration with an approximately 4.5-megaton warhead and a roughly ten-minute launch time. The National Air and Space Museum identifies the Mark 4 reentry vehicle as the reentry vehicle used on Atlas E/F and Titan I ICBMs, carrying a W-38 nuclear warhead with a yield of about 3.75 megatons.

Operationally, the launch complex had to support alert monitoring, missile pressure maintenance, communications with SAC command channels, electrical and environmental support, RP-1 fuel handling, liquid-oxygen loading, emergency procedures, and security. The Atlas F was more survivable than earlier Atlas variants because it sat in a hardened silo, but it remained exposed during the final preparation period when the missile was raised and liquid oxygen was loaded. This vulnerability was one reason Atlas F was quickly overtaken by later silo-launched systems.

Unlike a Minuteman Launch Facility, an Atlas F site contained substantial launch-control and support infrastructure at the individual missile complex. Personnel could be present at the site for alert, maintenance, training, inspection, security, and propellant operations.

Operational History

Site 577-11's active operational life was brief but intense. The 577th Strategic Missile Squadron activated at Altus AFB on 1961-06-01 and operated twelve Atlas F launch complexes distributed around southwestern Oklahoma and nearby Texas. The squadron was assigned to the 11th Bombardment Wing and later the 11th Strategic Aerospace Wing. USAF unit-history material identifies SM-65F Atlas as the squadron's missile weapon system from 1961 to 1965.

The first Series F Atlas ICBM at the 577th SMS was placed on alert early in August 1962. By October 1962, the squadron reached operational status. The timing mattered. The Cuban Missile Crisis unfolded later that month, and USAF unit-history material states that all twelve missiles were put on alert status as a result of the crisis. Site 577-11 was therefore part of an Atlas F force that entered alert duty during one of the most dangerous periods of the Cold War.

Day-to-day operations at Site 577-11 would have centered on maintaining a liquid-fueled first-generation ICBM in a usable alert condition. That work included launcher-system inspections, electrical and communications checks, environmental-control maintenance, propellant-system readiness, security response, periodic exercises, and coordination between missile crews, maintenance teams, security personnel, and higher headquarters. The site also had to remain ready for liquid-oxygen operations, a demanding process that required trained crews, carefully maintained ground equipment, and strict safety discipline.

The strongest site-specific visual evidence for operations at Site 577-11 is the pair of propellant-loading-exercise photographs. They show the missile raised from the silo and surrounded by visible vapor, indicating a training or test evolution rather than a launch. These images do not by themselves document a named exercise date, but they do confirm that Site 577-11 participated in the kind of propellant-loading work that defined Atlas F operations.

Site 577-11's operational missile was not the first missile assigned to the site. Atlas 87F replaced Atlas 68F as the operational ICBM for 577th SMS Site 11. Atlas 87F was accepted on 1963-03-21 and delivered on 1963-04-19. Its post-service launch history gives Site 577-11 a notable hardware afterlife. After the Atlas F ICBM force was retired, many Atlas missiles were refurbished as space launch vehicles. Missile 87F later launched NOAA-C, renamed NOAA-7, from Vandenberg Space Launch Complex 3 West on 1981-06-23. WMO records NOAA-7 as a NOAA/NASA satellite launched on that date, and the Cape Canaveral Space Force Museum identifies 1981-06-23 as the last Atlas F launch from SLC-3W. 87F was the final launch of an Atlas F series missile.

Deactivation and Disposal

The Atlas F weapon system had a short service life. By late 1964, the Department of Defense had decided to accelerate the retirement of remaining Atlas D, Atlas E, Atlas F, and Titan I systems. The SAC Missile Chronology records the broader sequence of late-1964 Atlas removals from alert and the planned phaseout of older ICBM systems. USAF unit-history material records the 577th SMS phaseout sequence: the first 577th SMS ICBM was removed from alert on 1964-12-30, the last was removed from alert on 1965-02-04, and the last was shipped on 1965-02-10.

The 577th Strategic Missile Squadron was inactivated on 1965-03-25,. Its assigned missile, Atlas 87F / tail number 573, was not scrapped immediately after missile-field service. It later served as a space launch vehicle and launched NOAA-C / NOAA-7 from Vandenberg in 1981.

After deactivation, Site 577-11 left active military service and eventually entered environmental tracking as a Formerly Used Defense Site. The 2015 U.S. Army Corps of Engineers FUDS inventory lists WILLOW, ATLAS MISSILE NO. 11, K06OK0411, with Hazardous, Toxic, and Radioactive Waste and Building Demolition / Debris Removal entries. ProPublica's DERP-based summary lists ATLAS MISSILE NO. 11 at Willow, Greer County, as Response Complete.

Current Status and Site Use

Site 577-11 is a decommissioned former Atlas F launch complex in Greer County, Oklahoma. It is not an active military installation. The current individual parcel owner was not verified, but the site should be treated as private or otherwise non-public property.

Satellite imagery indicate that visible former launch-complex features remain at or near the coordinate, including the surface footprint of the launch area and associated former Atlas F structures or pads. However, public imagery alone should not be used to infer safe access or structural condition. Former Atlas F complexes can contain underground confined spaces, water hazards, deteriorated concrete and steel, old utility systems, environmental residues, and fall hazards.

Public access should be treated as prohibited unless the current owner provides explicit permission. Lawful roadside observation is the only appropriate public-viewing assumption.

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.
• 1960-07-01 Construction began at Atlas F Site 577-11 near Willow, Oklahoma.
• 1961-06-01 The 577th Missile Squadron activated at Altus AFB to operate twelve Atlas F launch sites.
• 1961-10-04 Site 577-11 was turned over to the Air Force.
• 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 chronology states 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.
• 1963-03-21 Atlas missile 87F / serial number 61-2573 / tail number 573 was accepted.
• 1963-04-19 Atlas missile 87F was delivered for the Altus operational ICBM mission.
• 1964-05-14 A propellant-loading explosion destroyed squadron Site 577-6 near Frederick, Oklahoma; this did not occur at Site 577-11.
• 1964-11-19 Secretary of Defense Robert S. McNamara announced the planned phaseout of Atlas D, Atlas E, Atlas F, and Titan I missiles by the end of June 1965.
• 1964-12-30 USAF unit-history material records the first 577th SMS ICBM removed from alert.
• 1965-02-04 USAF unit-history material records the last 577th SMS ICBM removed from alert.
• 1965-02-10 USAF unit-history material records the last 577th SMS ICBM shipped.
• 1965-03-25 Site 577-11 was decommissioned and the 577th Strategic Missile Squadron was inactivated.
• 1981-06-23 Former Site 577-11 missile 87F successfully launched NOAA-C / NOAA-7 from Vandenberg AFB Space Launch Complex 3 West; this was not a launch from the Willow site.
• 2015-09-30 The USACE FUDS Oklahoma inventory listed WILLOW, ATLAS MISSILE NO. 11, K06OK0411, with HTRW and BD/DR entries.

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