The High Frequency Global Communications System (HFGCS) is a network of

single sideband In radio communications, single-sideband modulation (SSB) or single-sideband suppressed-carrier modulation (SSB-SC) is a type of modulation used to transmit information, such as an audio signal, by radio waves. A refinement of amplitude modul ...

shortwave Shortwave radio is radio transmission using shortwave (SW) radio frequencies. There is no official definition of the band, but the range always includes all of the high frequency band (HF), which extends from 3 to 30 MHz (100 to 10 me ...

transmitters of the

United States Air Force The United States Air Force (USAF) is the air service branch of the United States Armed Forces, and is one of the eight uniformed services of the United States. Originally created on 1 August 1907, as a part of the United States Army Signal ...

which is used to communicate with aircraft in flight, ground stations and some

United States Navy The United States Navy (USN) is the maritime service branch of the United States Armed Forces and one of the eight uniformed services of the United States. It is the largest and most powerful navy in the world, with the estimated tonnage ...

surface assets. All worldwide receiving and transmitting sites in the HFGCS system are remotely controlled from

Andrews Air Force Base Andrews Air Force Base (Andrews AFB, AAFB) is the airfield portion of Joint Base Andrews, which is under the jurisdiction of the United States Air Force. In 2009, Andrews Air Force Base merged with Naval Air Facility Washington to form Joint B ...

and Grand Forks Air Force Base. Before 1 October 2002 it was known as the Global High Frequency System (GHFS). HFGCS stations tend to operate in the aviation bands clustered around 5, 6, 8 and 11/12 MHz, although other frequencies are in use. The primary HFGCS voice frequencies are 4724.0 kHz, 8992.0 kHz, 11175.0 kHz, and 15016.0 kHz. In addition to the HFGCS, U.S. aircraft frequently use

Military Auxiliary Radio System The Military Auxiliary Radio System (MARS) is a United States Department of Defense sponsored program, established as a separately managed and operated program by the United States Army, and the United States Air Force. The United States Navy-M ...

(MARS) HF stations (13927.0 kHz) and

Canadian Forces } The Canadian Armed Forces (CAF; french: Forces armées canadiennes, ''FAC'') are the unified military forces of Canada, including sea, land, and air elements referred to as the Royal Canadian Navy, Canadian Army, and Royal Canadian Air Force. ...

HF stations (11232.0 kHz) to relay messages. Various other discrete frequencies are available, and used, as part of the HFGCS network and are not listed here. One common use for the HFGCS is to place telephone calls from the aircraft in flight by means of the

Defense Switched Network The Defense Switched Network (DSN) is a primary information transfer network for the Defense Information Systems Network (DISN) of the United States Department of Defense. The DSN provides the worldwide non-secure voice, secure voice, data, facsim ...

(DSN) to an U.S. Air Force base, U.S. Naval Air Station, U.S. Marine Corps Air Station, U.S. Army Airfield, or Air Force Reserve or Air National Guard installations on civilian airports, or Army Reserve or Army National Guard Aviation Support Facilities on civilian airports, to obtain local weather conditions, to arrange for refueling, and to inform the base of the number of passengers and crew. The HFGCS also carries

Emergency Action Messages 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 ...

(EAMs). In addition to EAMs, the HFGCS carries a few other types of messages. A higher priority code for orders is a Skyking Message, which is a time sensitive message for orders that need immediate attention. Force Direction Messages (FDM's) are also sent through the HFGCS, although it is impossible to tell whether the message is an FDM or just another EAM being read. The sign off 'Crossfire' was in use in August 2021 at the end of the transmissions. This changes from time to time, as an example 'Colour Bar' was being used in 2016. As of March 2021, the identifier being used was 'Silicate'. By summer of 2022, callsign signoffs were being changed on a daily basis. Although transmissions are often

(SSB), the use of the

ALE Ale is a Type of beer, type of beer brewed using a Warm fermentation, warm fermentation method, resulting in a sweet, full-bodied and fruity taste. Historically, the term referred to a drink brewed without hops. As with most beers, ale typicall ...

transmission mode is more and more common. HFGCS complements the use of satellite communications between aircraft and ground stations. Stations of the HFGCS Network * Andersen Global,

Andersen Air Force Base Andersen Air Force Base (Andersen AFB, AAFB) is a United States Air Force base located primarily within the village of Yigo in the United States territory of Guam. The host unit at Andersen AFB is the 36th Wing (36 WG), assigned to the Pacific ...

, Guam, USA * Andrews Global,

, Maryland, USA * Ascension Global, RAF Ascension Island/Ascension Auxiliary Field, Ascension Island, British Overseas Territories * Croughton Global,

RAF Croughton Royal Air Force Croughton or more simply RAF Croughton is a Royal Air Force station which is currently a United States Air Force communications station in Northamptonshire, England. It is southeast of the village of Croughton. The station is ...

, United Kingdom * Diego Garcia Global, U.S. Naval Support Facility Diego Garcia, British Indian Ocean Territory * Elmendorf Global, Elmendorf Air Force Base, Alaska, USA * Hickam Global,

Joint Base Pearl Harbor–Hickam Joint Base Pearl Harbor–Hickam (JBPHH) is a United States military base on the island of Oahu, Hawaii. It is Joint Base, an amalgamation of the United States Air Force's Hickam Air Force Base and the United States Navy's Naval Station Pearl ...

( Hickam Air Force Base), Hawaii, USA * Lajes Global, Lajes Field, Azores, Portugal * Lincoln Receiver Site (aka West Coast Global), Beale Air Force Base, California, USA * Offutt Global,

Offutt Air Force Base Offutt Air Force Base is a U.S. Air Force base south of Omaha, adjacent to Bellevue in Sarpy County, Nebraska. It is the headquarters of the U.S. Strategic Command (USSTRATCOM), the 557th Weather Wing, and the 55th Wing (55 WG) of the Air ...

Nebraska Nebraska () is a state in the Midwestern region of the United States. It is bordered by South Dakota to the north; Iowa to the east and Missouri to the southeast, both across the Missouri River; Kansas to the south; Colorado to the southwe ...

, USA * Puerto Rico Global, Salinas, Puerto Rico, USA * Sigonella Global, U.S. Naval Air Station Sigonella, Sicily, Italy * Yokota Global, Yokota Air Base, Japan Closed Stations (GHFS and HFGCS) * Thule Global, Thule Air Base,

Greenland Greenland ( kl, Kalaallit Nunaat, ; da, Grønland, ) is an island country in North America that is part of the Kingdom of Denmark. It is located between the Arctic and Atlantic oceans, east of the Canadian Arctic Archipelago. Greenland is t ...

* Keflavík Global, former U.S. Naval Air Station Keflavík, Iceland * Loring Global, former Loring Air Force Base, Maine, USA * MacDill Global, MacDill Air Force Base, Florida, USA * Scott Global, Scott Air Force Base, Illinois, USA * McClellan Global, former McClellan Air Force Base, California, USA * Bayonne Global (Bayonne, New Jersey); a former USTRANSCOM station operated by the Surface Deployment and Distribution Command (SDDC) from 1989 to 1999.

References

Further reading