USAF High Frequency Global Communications System

USAF HIGH FREQUENCY GLOBAL COMMUNICATIONS SYSTEM (HFGCS)

GENERAL - The HFGCS System is a worldwide network of 15 high-power HF stations providing air/ground HF command and control radio communications between ground agencies and US military aircraft and ships. Allied military and other aircraft are also provided support IAW agreements and international protocols as appropriate. The HFGCS is not dedicated to any service or command, but supports all DoD authorized users on a traffic precedence/priority basis. General services provided by the HFGCS are:

• General Phone Patch and Message Relay Services
• Automatic Link Establishment (ALE)
• HF Data Support
• Command and Control Mission Following
• Emergency Assistance
• Broadcasts
• HF Direction Finding Assistance
• ATC Support
• E-Mail connectivity to NIPRNeT and SIPRNeT

MODERNIZATION - SCOPE Command replaces older high power Global HF equipment. SCOPE Command incorporates Automatic Link Establishment (ALE) to automate communications. All HFGCS station transmit and receive equipment is remotely controlled from the Centralized Network Control Station (CNCS) at Andrews AFB, MD.

General Calling. Aircrews use a preliminary call as outlined in ACP-121 US Supp 2 using the collective callsign "MAINSAIL" or the HFGCS station call sign (example: Sigonella Global this is Dark 86 on 11175, OVER). HFGCS operators require approximately 10 seconds (for automated equipment configuration) to respond to calls for service. The HFGCS operator may request the aircraft change to a discrete frequency for improved and/or extended service.

(a) PUBLISHED FREQUENCY LISTING - frequencies to provide increased "Global" coverage. The published frequency listing does not reflect complete system frequency authorizations. These published frequencies will be used for initial contact, EAM broadcasts, and short-term C2 phone patch and message delivery. Other extended or special services will be moved to each station’s available "discrete" frequencies.

(b) FREQUENCY GUIDE - The frequency guides are designed to optimize air/ ground communications.

Primary HFGCS Frequencies 24 Hours:   8992 and 11175
Back up HFGCS Frequencies Day:        13200 15016
Back up HFGCS Frequencies Night:      4724 6739

                         DISTANCE (1)
TIME (2)
       200-7500 NM      750-1500 NM           More than 1500 NM
-------------------------------------------------------------------
0000L   4724            6712-6739-8992        6712-6739-8992-11175
0400 L  4724            4724-6712-6739        6712-6739-8992
0800 L  4724-6712-6739  6712-6739-8992-11175  11175-13200-15016
1200 L  4724-6712-6739  8992-11175-13200      13200-15016
1600 L  4724-6712-6739  8992-11175-13200      13200-15016
2000 L  4724-6712-6739  6712-6739-8992-11175  1175-13200-15016

1. When less than 200 NM any frequency
2. Local time at ground station.

FREQUENCIES - SUMMER (Apr-Sep)
STATION    4724       6712        6739        8992      11175     13200       15016
-------------------------------------------------------------------------------------
Andrews   0500-1330Z              0300-1600Z  24 hours  24 hours  1330-0500Z  1600-0300Z
Ascension 2300-0700Z              2200-0900Z  24 hours  24 hours  0700-2300Z  0900-2200Z
Croughton 2300-0600Z  2100-0800Z              24 hours  24 hours  0600-2300Z  0800-2100Z
Diego
Garcia    1400-0100Z              1200-0200Z  24 hours  24 hours  0100-1400Z  0200-1200Z

Elmendorf 0600-1500Z 0400-1700Z 24 hours 24 hours 1500-0600Z 1700-0400Z Guam 1300-2200Z 1100-2400Z 24 hours 24 hours 2200-1300Z 2400-1100Z Hawaii 0800-1700Z 0700-1800Z 24 hours 24 hours 1700-0800Z 1800-0700Z Keflavik 1930-0600Z 1630-1000Z 24 hours 24 hours 0600-1930Z 1000-1630Z Lajes 2200-0800Z 2000-1200Z 24 hours 24 hours 0800-2200Z 1200-2000Z Offutt 0400-1330Z 0200-1700Z 24 hours 24 hours 1330-0400Z 1700-0200Z Puerto Rico 0400-1200Z 0100-1400Z 24 hours 24 hours 1200-0400Z 1400-0100Z Sigonella 2200-0530Z 1900-0900Z 24 hours 24 hours 0530-2200Z 0900-1900Z West Coast 0600-1400Z 0300-1800Z 24 hours 24 hours 1400-0600Z 1800-0300Z Yokota 1300-2200Z 1100-2200Z 24 hours 24 hours 2200-1300Z 2200-1100Z