Loring Air Force Base, Maine 

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Strategic Air Command's Green Pine Network
The Role of Loring Air Force Base, Maine

July 2006

It was not listed in the base phone book. It didn't have an office on base. But Loring AFB was an administrative support base for one of Strategic Air Command's (SAC) Green Pine Stations at Argentina, Newfoundland. This detachment consisted of six people. Located in the top floor of an unused Bachelors Officers Quarters BOQ unit at Naval Air Station Argentina, Newfoundland, a former airfield of the United States Navy. 1

For pictures of the Q: http://www.pwgsc.gc.ca/argentia/images/cbqoperation.jpg

Green Pine's mission was to act as an Ultra High Frequency (UHF) radio beacon to pass Emergency Action Messages (EAMs) to SAC aircraft. Each station was equipped with the Survivable Low Frequency Communication System (SLFCS). Messages received over the SLFCS were relayed via UHF channels to transiting SAC aircraft.

Green Pine is also known as: 488L - "GREEN PINE" NAUHF (Northern Area Ultra High Frequency) Radio System; North Area Communications System; Northern Area Communications System (NACS). 2

Why Green Pine?

This system was needed to increase the likelihood of SAC aircrews receiving EAMs while airborne and enroute to their hold points during wartime. SACs heavy reliance on the High Frequency (HF) spectrum for worldwide communications was negatively offset by the vulnerability of such systems to the effects of nuclear detonations. 3

System Limitations

HF radio worked fine in peacetime. In wartime, HF radio could be disrupted. After nuclear detonations the atmosphere is disrupted. When a HF radio signal is transmitted the characters in the transmission will be lost and only part of the message could be received or not at all. Without that vulnerability, EAMs could be transmitted reliably during all phases of a nuclear attack (assuming ground stations were not attacked).

UHF and Low Frequency (LF) radio systems were not as vulnerable though these had limitations. UHF was "line-of-site". 4 From a ground tower to aircraft at 35,000 feet, range was approximately 240 miles. 5

LF systems (Survivable Low Frequency Communication System SLFCS) had sufficient range but was limited by low data rate messages during pre,-trans-, and post-attack scenarios. SLFCS could transmit in two modes, from the ground station or from one of the airborne command posts with a trailing wire antenna. Ground stations were vulnerable to attack and the airborne systems were limited in time the antenna could be deployed. Trailing wire antenna systems had questionable reliability, as they would periodically break off the aircraft while deployed. 6

The Solution

When the SAC bomber/tanker force was launched they would be out of UHF range within hours and upon entering the higher latitudes could no longer rely on HF communications. Not equipped with LF receivers they relied on UHF, if available, and HF if not disrupted.

A UHF system located in the upper latitudes would provide transiting bombers with a direct line to SAC Command and Control. SAC crews could receive EAMs for a longer period of time. This provided highly survivable and reliable command, control and communications among the president, secretary of defense and U.S. forces during national emergencies. 7

In 1967, SAC set up an arc of UHF beacon stations from Adak Island, Alaska to Grindavik, Iceland. These stations were equipped with HF and SLFCS receivers and two UHF transceivers. Should SAC launch the alert force, bomber crews would attempt to contact one of these beacon stations for EAM traffic. SAC Command and Control (Looking Glass, SAC Headquarters, Headquarters Emergency Relocation Team (HERT) 8th and 15 AF Headquarters) could inject EAM traffic into the SLFCS, HF (Giant Talk) systems. These messages received by Green Pine Stations would be relayed and repeated over the UHF band automatically and on demand.

The SLFCS antenna was comprised of two large "loops" (about three feet in diameter) that were arranged 90 degrees to one another on the same axis. It was known as the "orange peel" antenna (looked like a peeled orange and was orange in color) and sat outside on the ground near the surveillance room. 8 The Green Pine antenna was a vertical UHF array that was enclosed in a cylindrical fiberglass radome that was approximately 20 inches in diameter by 8 feet in length. At Alaska and Canadian sites these antennae were usually mounted atop a 60-foot telephone pole. 9

These stations would remain in operation until they too were attacked. Should a station fail, bomber crews used a "hand off" system where the trailing bombers leaving UHF coverage in the US would pass the last received EAM to the leading outbound bombers. 10

Other Solutions (1970s)

Emergency Rocket Communications System (ERCS)

Adding another layer of UHF connectivity, SAC implemented the UHF Emergency Rocket Communications System (ERCS) to provide a reliable and survivable command, control, and communications connectivity between command posts and launch control centers. The ERCS UHF transmitters carried prerecorded EAMs that could were transmitted to all units within line of sight of a rocket's apogee flight. Ten missiles provided coverage over the North American continent. Flight time was approximately 30 minutes.

Air Force Satellite Communication System. (AFSATCOM)

Air Force Satellite Communications (AFSATCOM) provide secure, reliable, and survivable satellite communications for Air Force Single Integrated Operation Plan (SIOP) forces and other selected high priority users. 11

Where Were the Stations?

The main Green Pine communication node is located at Annex 2, Elkhorn, Nebraska. This control station is connected to the SAC command center at Omaha, Nebraska and with Green Pine sites. Nearby is one of two SLFCS ground station at Silver Creek, Nebraska. Logistics support for Green Pine came from Sacramento Air Logistics Center CA.

Some Green Pine stations were collocated with Distant Early Warning (DEW Line) main stations.

Figure 1 Green Pine Locations with 200-mile range circles.

Green Pine stations were located at:

Adak Island, Alaska
Cape Parry, NWT - PIN-Main
Cambridge Bay NWT - CAM-Main
Hall Beach, NWT - FOX-Main
Cape Dyer, NWT - DYE-Main
Melville AS, NFLD
Argentia NFLD
Loring Air Force Base, Maine
Naval Radio Transmitter Facility (NRTF) Grindavik, Iceland 13

Some references include Point Barrow and Barter Island as Green Pine Stations.14

Figure 2 Map with Point Barrow and Barter Island noted.


Technicians and operators usually had SLFCS experience and were drawn from one the other 200 SLCFS sites. Approximately six technician/operators were assigned per station. It is estimated about 100 personnel were affiliated with Green pine and any given time. 15

Operations Today (Post Cold War)

Green Pine is gone now, phased out in 1987. 16 ERCS is gone as well. SLFCS is still around but modified. Bombers can now receive direct LF transmitted EAMS. B-1 and B-52 bombers are equipped with Miniature Receive Terminals (MRTs). 17

The MRT is a Very Low Frequency/Low Frequency (VLF/LF) receiver installed in the B-1 and B-52 bombers. 18 B-1s are no longer used for nuclear missions 19 and B-2s are equipped with AN/ARC-211 HF, AN/ARC-215 VHF/UHF, 20 AN/ARR-85 VLF/LF receiver and Milstar satellite communications EHF communications. 21

The Very Low Frequency/Low Frequency (VLF/LF) and Strategic Automated Command and Control System (SACCS) teletype communication paths will remain critical components of strategic command and control. The requirement to upgrade the Survivable Low Frequency Communications System (SLFCS) receivers with Modified Miniature Receive Terminals (MMRTs) is associated with upgrading the timing and availability of the second survivable EAM path. 22

AFSATCOM UHF was considered less susceptible to the effects of nuclear detonations. The Joint Staff has mandated all nuclear users shall migrate off the AFSATCOM constellation into the EHF extremely high frequency spectrum. Because the AFSATCOM Terminal operates in the UHF frequency band, it cannot be considered a survivable system. Communications in this band are not capable of continued transmission/reception in a nuclear environment. 23

More on Naval Station Argentia, Newfoundland





1 Mark Brueggemann, former Green Pine System Operator. 2005.

2 Designations Of U.S. Air Force Projects. 2000-2006 Andreas Parsch. http://www.designation-systems.net/usmilav/projects.html

3 Strategic Command and Control Bruce Blair. 1985.

4 Ibid.

5 Managing Nuclear Operations. Ashton Carter. 1987.

6 Strategic Command and Control. Bruce Blair

7 New joint system built to survive 'unthinkable'. Chuck Paone. Hansconian. Online News Summary. 2002. http://www.hanscom.af.mil/hansconian/2002/May/05242002/05242002-PS.htm

8 Clive Beckmann. 487L Survivable Low Frequency Communication System (SLFCS). http://www.lswilson.ca/dewline.htm#N. June 21, 2006

9 Clive Beckmann. 488L UHF Green Pine Communication System. http://www.lswilson.ca/dewline.htm#N. June 21, 2006

10 The Button. Daniel Ford. 1985.

11 Air Force Satellite Communications. AFSATCOM. http://www.fas.org/spp/military/program/nssrm/initiatives/afsatcom.htm

12 In Arkin's Nuclear Battlefields, Loring AFB is a designated Green Pine system. This is unlikely due to location, redundancy of existing command and control equipment.

13 Nuclear Battlefields, Arkin.1985.

14 Beckman notes all DEW-Main stations had Green Pine. Arkin lists stations but does not annotate Green Pine role. Questioned locations are Point Barrow, AK (POW-Main) and Barter Island (BAR-Main). Personal communications indicates Arkin is correct.

15 Author's Estimates.

16 Brueggemann. 2005.

17 Modified Miniature Receive Terminal. (MMRT). February 1997. http://www.fas.org/spp/military/program/nssrm/initiatives/mmrt.htm

18 Ibid.

19 NRDC: Nuclear Notebook: U.S. nuclear forces, 2003. Robert S. Norris and Hans M. Kristensen
May/June 2003.

20 AN/ARA to AN/ARC - Equipment Listing. 2000-2005 Andreas Parsch. http://designation-systems.net/usmilav/jetds/an-ara2arc.html

21 Modified Miniature Receive Terminal. Rockwell Collins. http://collins-gps.com/ecat/GS/MMRT_PrintFriendly.html

22 Survivable Low Frequency Communications System (SLFCS). 2006. http://www.globalsecurity.org/wmd/systems/slfcs.htm

23 Extremely High Frequency (EHF). Capability For The ICBM Launch Control Centers. Brian A. Arnold Brigadier General, USAF. April 1997. http://fas.org/nuke/guide/usa/c3i/ehf_ord7.html

Note: If you have information, photos or comments please direct them to Michael Makar, mikemakar@aol.com. Be sure to include "Green Pine" in the Subject line.

Website Contact: Michael Makar, Bradenton, FL Email: mikemakar@aol.com

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