The AN/FRC-117 Survivable Low Frequency Communications System (SLFCS) was a communications system designed to be able to operate, albeit at low

data transfer rate Data rate and data transfer rate can refer to several related and overlapping concepts in communications networks: Achieved rate * Bit rate, the number of bits that are conveyed or processed per unit of time ** Data signaling rate or gross bit rate ...

s, during and after a

nuclear attack Nuclear warfare, also known as atomic warfare, is a theoretical military conflict or prepared political strategy that deploys nuclear weaponry. Nuclear weapons are weapons of mass destruction; in contrast to conventional warfare, nuclear wa ...

. The system used both very low frequency (VLF), and

low frequency Low frequency (LF) is the ITU designation for radio frequencies (RF) in the range of 30–300 kHz. Since its wavelengths range from 10–1 km, respectively, it is also known as the kilometre band or kilometre wave. LF radio waves exh ...

(LF) radio bands.

Mission

SLFCS was used for United States nuclear forces' command and control communications for

Emergency Action Message In the United States military's strategic nuclear weapon nuclear command and control (NC2) system, an Emergency Action Message (EAM) is a preformatted message that directs nuclear-capable forces to execute specific Major Attack Options (MAOs) o ...

dissemination and force direction. Single channel, receive only capability was provided at

ICBM An intercontinental ballistic missile (ICBM) is a ballistic missile with a range greater than , primarily designed for nuclear weapons delivery (delivering one or more thermonuclear warheads). Conventional, chemical, and biological weapons c ...

launch control centers. The single channel operated between 14 kHz and 60 kHz to receive commands from remotely located Combat Operations Center – Transmit/Receive (T/R) sites; this low frequency range is only slightly affected by nuclear blasts. SLFCS' primary advantage was that it would experience minimal radio signal degradation as a result of nuclear detonations. It would be an alternate means of communication during and after detonations, providing a survivable command and control communications network for the

Strategic Air Command Strategic Air Command (SAC) was both a United States Department of Defense Specified Command and a United States Air Force (USAF) Major Command responsible for command and control of the strategic bomber and intercontinental ballistic missile ...

(

SAC SAC or Sac may refer to: Organizations Education * Santa Ana College, California, US * San Antonio College, Texas, US * St. Andrew's College, Aurora, Canada * Students' Administrative Council, University of Toronto, Canada * SISD Student Activiti ...

), the Joint Chiefs of Staff ( JCS), and North American Aerospace Defense Command (

NORAD North American Aerospace Defense Command (NORAD ), known until March 1981 as the North American Air Defense Command, is a combined organization of the United States and Canada that provides aerospace warning, air sovereignty, and protection ...

). SLFCS would also relay signals from the Navy's LF/ VLF systems.

Locations

Transmitters

* Silver Creek, Nebraska (1st Aerospace Communications Group) * Hawes Air Force Station, California (Det 2, 33rd Communications Squadron) * PACCS aircraft * NAOC (formerly known as NEACP)

GREEN PINE Stations

The GREEN PINE communication system took messages broadcast over SLFCS and 'upconverted' them to UHF messages for bombers headed north. There were a handful of GREEN PINE stations in the northern portions of Alaska and Canada.

Receive Only

* Altus AFB,

Oklahoma Oklahoma (; Choctaw language, Choctaw: ; chr, ᎣᎧᎳᎰᎹ, ''Okalahoma'' ) is a U.S. state, state in the South Central United States, South Central region of the United States, bordered by Texas on the south and west, Kansas on the nor ...

* Barksdale AFB, Louisiana (

8th Air Force Command Post 8 (eight) is the natural number following 7 and preceding 9. In mathematics 8 is: * a composite number, its proper divisors being , , and . It is twice 4 or four times 2. * a power of two, being 2 (two cubed), and is the first number of t ...

) * Beale AFB, California ( 9 SRW Command Post) * Blytheville AFB, Arkansas ( 97 BW Command Post) * Carswell AFB, Texas ( 7 BW Command Post) * Castle AFB, California ( 93 BW Command Post) * Davis-Monthan AFB, Arizona - 390th SMW (18 LCCs) CLOSED * Dyess AFB, Texas ( 96 BW Command Post) * Eielson AFB, Alaska ( 6 SW Command Post) * Ellsworth AFB, South Dakota - 44th SMW (16 terminals - 15 LCCs and Wing Command Post) CLOSED * Fairchild AFB, Washington *

F.E. Warren AFB Francis E. Warren Air Force Base , shortened as F.E. Warren AFB is a United States Air Force base (AFB) located approximately west of Cheyenne, Wyoming. It is one of three strategic-missile bases in the U.S. It was named in honor of Francis E ...

, Wyoming - 90th Missile Wing, 20th Air Force (21 terminals- 20 LCCs, 1 at 20th AF Missile Operations Center) *

Grand Forks AFB Grand Forks Air Force Base (AFB) is a United States Air Force installation in northeastern North Dakota, located north of Emerado and west of Grand Forks. The host unit is the 319th Reconnaissance Wing (319 RW) assigned to the Air Combat C ...

, North Dakota - 321st SMW (16 terminals - 15 LCCs and Wing Command Post) CLOSED *

Griffiss AFB Griffiss Air Force Base is a former United States Air Force installation in the northeastern United States, located in Central New York state at Rome, about northwest of Utica. Missions included fighter interceptors, electronic research, i ...

New York New York most commonly refers to: * New York City, the most populous city in the United States, located in the state of New York * New York (state), a state in the northeastern United States New York may also refer to: Film and television * '' ...

CLOSED *

Grissom AFB Grissom Air Reserve Base is a United States Air Force base, located about north of Kokomo in Cass and Miami counties in Indiana. The facility was established as a U.S. Navy installation, Naval Air Station Bunker Hill, in 1942 and was an active ...

, Indiana *

K.I. Sawyer AFB K. I. Sawyer Air Force Base is a decommissioned United States Air Force (USAF) installation in Marquette County, Michigan, south of the city of Marquette. Near the center of Michigan's Upper Peninsula, the base operated for nearly forty years ...

, Michigan CLOSED *

Little Rock AFB Little Rock Air Force Base is a United States Air Force base located approximately northeast of Little Rock, Arkansas. Little Rock AFB is the primary C-130 Hercules training base for the Department of Defense, training C-130 pilots, navigat ...

, Arkansas - 308th SMW (18 LCCs) CLOSED * Loring AFB, Maine ( 42 BW Command Post) CLOSED *

Rickenbacker AFB Rickenbacker Air National Guard Base is an Ohio Air National Guard installation located near Lockbourne in southern Franklin County. The base was named for the famous early aviator and Columbus native Eddie Rickenbacker. It is the home of t ...

, Ohio * Malmstrom AFB, Montana 341st SMW (20 terminals - 20 LCCs) * Mather AFB, California * McConnell AFB, Kansas 22 BW (Command Post), 381st SMW (18 LCCs) CLOSED * Minot AFB, North Dakota ( 5 BW/ 91 SMW 15 LCCs) *

Pease AFB Pease Air National Guard Base is a New Hampshire Air National Guard base located at Portsmouth International Airport at Pease in New Hampshire. It occupies a portion of what was once Pease Air Force Base, a former Strategic Air Command facility ...

, New Hampshire ( 509 BW Command Post) CLOSED *

Plattsburgh AFB Plattsburgh Air Force Base is a former United States Air Force Strategic Air Command (SAC) base covering 3,447 acres (13.7 km²) in the extreme northeast corner of New York, located on the western shore of Lake Champlain opposite Burlingto ...

( 380 BW Command Post) CLOSED *

Robins AFB Robins Air Force Base is a major United States Air Force installation located in Houston County, Georgia, United States. The base is located just east of the city of Warner Robins, south-southeast of Macon and approximately south-southeast ...

, Georgia ( 19 BW Command Post) *

Seymour Johnson AFB Seymour Johnson Air Force Base is a United States Air Force (USAF) base located in Goldsboro, North Carolina. The base is named for U.S. Navy Lt. Seymour A. Johnson, a test pilot from Goldsboro who died in an airplane crash near Norbeck, Maryland, ...

, North Carolina ( 68 BW Command Post) * Travis AFB, California * Vandenberg AFB, California ( 1 STRAD Command Post)1 LCC O1A * Whiteman AFB, Missouri - 351st SMW (16 terminals - 15 LCCs and Wing Command Post) CLOSED *

Wurtsmith AFB Wurtsmith Air Force Base is a decommissioned United States Air Force base in Iosco County, Michigan. It operated from 1923 until decommissioned in 1993. On January 18, 1994 it was listed as a Superfund due to extensive groundwater contaminati ...

, Michigan ( 379 BW Command Post) *

March AFB March Air Reserve Base (March ARB), previously known as March Air Force Base (March AFB) is located in Riverside County, California between the cities of Riverside, Moreno Valley, and Perris. It is the home to the Air Force Reserve Command's Fo ...

, California (15th AF COC)

History

The first program (487L) took six years from the time of the initial requirement to full operation. The second part (616A), which was basically a modification of an already operational system, took 10 years.

Chronology

*1961 **29 Sep – Headquarters USAF issues Specific Operating Requirement 193, for the Survivable Low Frequency Communications System; system is envisioned to link Alternate Joint Command Center with command centers of SAC, NORAD, SAC numbered air forces with LF radio networks; a total of 18 transmit/receive (T/R) sites and 375 LF-receive only (R/O) in all SAC launch facilities, mobile Minuteman trains, SAC air base control rooms, and SAC UHF positive control stations in the northern tier *1962 **12 Mar – Amendment to SOR 193 changes number of transmit T/R sites to 19 (three each at AJCC, SAC, NORAD, two each at

2d Air Force The Second Air Force (2 AF; ''2d Air Force'' in 1942) is a USAF numbered air force responsible for conducting basic military and technical training for Air Force enlisted members and non-flying officers. In World War II the CONUS unit defended ...

15th Air Force The Fifteenth Air Force (15 AF) is a numbered air force of the United States Air Force's Air Combat Command (ACC). It is headquartered at Shaw Air Force Base. It was reactivated on 20 August 2020, merging the previous units of the Ninth Air Force ...

and 8th Air Force, one each at

Larson AFB Larson Air Force Base is a former United States Air Force base located five miles (8 km) northwest of the central business district (CBD) of Moses Lake, in Grant County, Washington. After its closure in 1966, the airport facility became G ...

, Southern Alaska, Sondrestrom AB, and the United Kingdom; Full Operating Capability was extended from July 1964 to May 1965. **27 Apr – A revised program directive delineated the network; T/R equipment would be installed at HQ SAC, the SAC numbered air force headquarters, and in the ABNCP, Alternate Joint Command Center (AJCC) and NORAD command center. 14 Green Pine stations, missile launch control centers, all SAC bomber wing command posts would have R/O terminals, as would the NORAD regional control centers. Initial Operating Capability (IOC) was placed at 1 Oct 1966. *1968 **29 Jul 1968 – Silver Creek site accepted by

Air Force Historical Research Agency: "History of 3902d Air Base Wing, July – September 1968" **19 Aug 1968 – Silver Creek site turned on for continuous operation **5 Sep 1968 – Silver Creek begins operational testing *1971 **16 Jun – SLFCS IOC obtained by

units *1974 **26 Jul – HQ USAF approves Program 616A (Improved SLFCS); system would improve SLFCS by providing anti-jam protection, improved

modems A modulator-demodulator or modem is a computer hardware device that converts data from a digital format into a format suitable for an analog transmission medium such as telephone or radio. A modem transmits data by Modulation#Digital modulati ...

, increased range and make it compatible with the Navy LF/VLF system *1978 **SAC conducts Initial Operational Test and Evaluation (IOT&E) at Ellsworth AFB, South Dakota for Program 616A; test is successful *1986 **30 Sep – deactivation of

Hawes Radio Relay Site Hawes Radio Relay Facility (also known as the Hawes Radio Tower) was a United States Air Force installation built on the site of the former Hawes Airfield at Hinkley, California, USA at . The site contained a guyed mast antenna and hardened und ...

, Hinkley, California **20 Oct – destruction of

by the Army Corps of Engineers *1996 ** Rapid Execution and Combat Targeting (REACT) upgrade to Minuteman

launch control center The Rocco A. Petrone Launch Control Center (commonly known as just the Launch Control Center or LCC) is a four-story building at NASA's Kennedy Space Center on Merritt Island, Florida, used to manage launches of launch vehicles from Kennedy Space ...

s complete; advances allow SLFCS messages to be handled automatically by Higher Authority Communications/Rapid Message Processing Element (HAC/RMPE) *2005 **11 Nov – last Minuteman

Launch Control Center The Rocco A. Petrone Launch Control Center (commonly known as just the Launch Control Center or LCC) is a four-story building at NASA's Kennedy Space Center on Merritt Island, Florida, used to manage launches of launch vehicles from Kennedy Space ...

receives Minimum Essential Emergency Communications Network ( MEECN) upgrade, rendering SLFCS obsolete.Air Force Space Command: "Minot completes final MEECN modifications", 17 Nov 2005
*2010 MMP – Minuteman Minimum Essential Emergency Communications Network Program now in the upgrade portion. Work In Progress. Advanced EHF will be available once upgrade is complete.

Photo gallery

File:33d Communications Squadron.PNG, 33d Comm Squadron, Hawes AFS, California File:1st Aerospace Communications Group.PNG, 1st Aerospace Comm Group, Offutt AFB, Nebraska

References

External links

Mojave Roads: "Hawes Journal"
{{USAF system codes Military radio systems of the United States Nuclear warfare United States Department of Defense Military communications of the United States United States nuclear command and control