What is an EAM? -
By Jeff Haverlah
From "Strategic Command, Control, and Communication - Alternative
Approaches For Modernization"; John J Hare, Richard H. Davison, and Peter
Tarpgaars; Congressional Budget Office (CBO); October 1981; Page 44:
"EAM: Though generally referring to a category of urgent messages from
commanders to deployed forces, EAM is often used as a short-hand
expression for a specially coded nuclear attack directive."
"....Proper coding and formatting of EAMs is of crucial importance,
since nuclear forces are prepared to execute any messages they receive
that meet rigid specifications. In addition to specific instructions
contained in an EAM, proper coding provides the means by which a
commander expresses his authority to release nuclear weapons and an
officer controlling those weapons verifies that authority."
From the May 1995 Monitoring Times; Utility World column by Larry Van
Horn; page 33; section titled "What are EAMs?":
" Several issues ago (Dec 94) we talked about the U.S. military's
Emergency Action Messages (EAM) broadcast. Here is an interesting
explanation, taken from a U.S. Air Force manual, of what an EAM is.
"Joint Chiefs of Staff Emergency Action Messages (EAMs) contain key
instructions or information from high level authority and have
predetermined formats (pro forma). Such messages are transmitted
by various communications systems and normally carry FLASH
precedence. They are vital messages of an extremely time-sensitive
nature, and rapid processing is mandatory to obtain the fast
reaction required by their content. Usage and handling procedures
are of the highest classification and have been issued by the JCS
only to those who have a need to know." (AFM-01-1-18, sub 3;
amended 01 Jan 1990)."
From a shortwave utility hobbyist's standpoint what are they? Park
your HF receiver (set to upper side band mode) on 15016.0 KHz, 13200.0 KHz,
11175.0 KHz (the most productive for day to day monitoring of the U.S.
military on HF), 8992.0 KHz (ideal for monitoring during North American
nights), 6739.0 Khz , 6712.0 KHz or 4724.0 Khz. Eventually you'll hear
ground stations of the USAF's HF-GCS (led by ANDREWS or OFFUTT or
MCCLELLAN, identified in the clear since 1992) broadcast one or more EAMs -
a six-character alpha-numeric string (known as the "preamble") read
phonetically, repeated three times, then followed by the same 6-character
string either by itself (as the entire message) or concatenated with
additional alpha-numeric characters to produce alpha-numeric strings that
total 28 characters (the most common length; 30-characters prior to 01 Oct
2000; 26-characters prior to 01 Oct 1998) or 22 characters (20 character
prior to 01 Oct 2000) or strings with character-counts that can extend into
the hundreds of characters (with the available character set universe
consisting of all 26-characters of the English alphabet plus the numerals
two, three, four, five, six and seven - with extremely rare exceptions there
are no zeros, ones, eights or nines heard in these strings). [Eventually
you might discover that this HF EAM activity is also heard on a group of HF
frequencies that are known as the ZULU frequencies utilized by communication
assets (both airborne and ground based) of the JCS and U.S. Strategic
Command (see the "Military Lists Area" column in any recent WUN
newsletter for the known frequencies) and on HF frequencies utilized by the
U.S. Navy during apparent exercises. However, since FY 2000 the ZULU
frequencies have become much less active with daily connectivity
communications to the point of silence.]
The above activity is heard daily, 7 days a week, 365 days a year,
year after year.
A second group of coded messages heard on the GHFS (and the ones that
produce the most comments from new listeners because of the "SKYKING do not
answer" nature of the broadcasts) are the so-called FOXTROT broadcasts.
These are heard only on the GHFS frequencies listed in the previous
paragraph and take the form of the GHFS operator broadcasting a message that
states "SKYKING, SKYKING. Do not answer. [3-element alpha-numeric group]
[minutestamp] [time dependent two-character authenticator]" and repeated
once. These transmissions appear to be initiated by any of the GHFS ground
stations except ASCENSION and HICKAM, with the initiating ground station
prefacing the broadcast with a codeword that can consist of DECENT (or
DESCENT), ENLIST, FAIRLY, EYESTRAIN (or sounds as), DEFROSTER, "ANY STATION"
and maybe one more codeword recently reported. The codeword appears to
determine which other GHFS ground stations are to "echo" the transmission.
As an example the DECENT transmission appears to apply only to CONUS
stations while all the others appear to apply (with an occasional exception)
to non-CONUS stations that fall outside an arc from Guam to Japan to Alaska
to Greenland to the UK to the Azores. These coded messages are said to be
*only* for the positive control of ACC/AMC airborne forces detailed to the
U.S. Strategic Command (USSTRATCOM). These messages appear to have higher
priority on the GHFS voice circuits than do the EAM transmissions as an EAM
transmission will be terminated in midstring in order to immediately
transmit these "SKYKING" DNA broadcasts.
04 Apr 2005:
The information in the above paragraph was written in 1998 and will
remain unaltered in the interest of "history;" however, unlike the subtly
changing information in the earlier EAM paragraph there are some notable
changes in the FOXTROT broadcasts since 1998.
---Prior to 1992 all FOXTROT broadcasts were initiated with aliased echo
rotation callups simlar to that described above.
---For a short time in the second half of 1992 (which represents the
activation of the USSTRATCOM following the deactivation of SAC) the
echo rotation callups were "in the clear."
---From maybe late in 1992 (or early 1993 lost in the fog of memory) the
GHFS went back to aliased callup echo rotations as described in the above
---In the 21 century the GHFS ceased to exist, replaced with the HF-GCS.
In the immediate post 11 September 2001 timeperiod, during the run up
to the purging of the Taliban from Afghanistan, the echo rotations
appeared to go through a transformation. They were no longer aliased and
at least two new stations were added to the echo rotation call up: DIEGO
GARCIA and for a brief period CYPRUS FLIGHT WATCH. After this conflict ALL
requests for echo rotation disappeared from the FOXTROT broadcasts, and it
remains that way into CY 2005.
Further detailed information can be found from the following sources:
1. Ary Boender's "Numbers & Oddities" column in the July 1995 (FOXTROT
broadcasts) and August 1995 ("EAMs") WUN Newsletters (both newsletters
are now "archived" at the WUN web site to save drive space -
wunv1n7.zip and wunv1n8.zip) - a short overview of how these broadcasts
0manifest themselves on various HF frequencies.
2. The December 1994 issue of Monitoring Times containing the "Utility
World" column of Larry Van Horn, titled "US Air Force Global High
Frequency (HF) System." A concise overview of the GHFS, and the
traffic contained on the GHFS.
The September 1995 issue of Monitoring Times containing the "Utility
World" column of Larry Van Horn, titled "What's the meaning behind the
messages." An overview of the "message" traffic heard on the GHFS and
the NIGHTWATCH net.
3. "The Aeronautical Communications Handbook - HF Edition" by Robert E.
Evans; 1989 (and out of print, I believe); pages 7.11-7.13. Written
while the Strategic Air Command was still in existence, so most of the
information is out of date in it's details, but apparently not in it's
overview of the EAMs.
There are no known public sources for detailed descriptions of these
strings, but there are a number of books and papers published that cover
this topic in broad strokes (and, which I suspect are in many ways greatly
out of date - I've found nothing that covers the post 1992 strategic world
in a way that is as detailed as they cover the pre 1992 world. It may be
too early to do so, as it is probably still in transition). Some examples
1. "The Logic of Accidental Nuclear War" by Bruce G. Blair; The Brookings
Institution; 1993 (still in print); ISBN 0-8157-0983-8 (paper). There
are numerous additional sources listed within the extensive "notes"
section of this book. The notes section also contains detailed
information that covers the uses of these messages.
2. "Strategic Command and Control - Redefining the Nuclear Threat by
Bruce G. Blair; The Brookings Institution; 1985 (still in print as of
the middle of 1996); ISBN 0-8157-0982-X (hardbound). Much of this
information covers what is now the foundation for today's strategic
world, but I suspect that many of the specific details covered in the
book are now greatly altered, maybe beyond recognition (such as the
integration of the USN into much of the then SAC-centric activity in
3. "Global Zero Alert for Nuclear Forces" by Bruce G. Blair; The
Brookings Institution; 1995 (May or so, and still in print); ISBN
0-8157-0941-2. The only "book" (it's actually an "occasional paper"
of 108 pages) in this group that can be said to be up-to-date in the
post 1992 strategic world. On EAMs, in particular see pages 59-60.
4. "Guarding the Guardians: Civilian Control of Nuclear Weapons in the
United States" by Peter Douglas Feaver; Cornell University Press; 1992
(out of print unfortunately). Mostly covers PAL (Permissive Action
Link) locks but has an overview on EAMs throughout the book.
6. "Dark Sun - The Making of the Hydrogen Bomb" by Richard Rhodes; Simon
and Schuster; 1995 (still in print); ISBN 0-684-80400-X. Page 573:
"..SAC routinely transmitted DefCon increases as unclassified messages
until 1972." Question: what happened after 1972? - "SAC routinely
transmitted DefCon increases as classified messages"?
5. The 10 May 1976 issue of "Aviation Week and Space Technology", devoted
almost entirely to the Strategic Air Command. Written during the
"Alpha Net" days of OFFUTT/BARKSDALE/WESTOVER/MARCH but has
information that might still apply in some aspects 20 years later
6. The Winter 1996 (Volume 27) issue of "World Air Power Journal" devoted
to the B-52H with a long article beginning on page 54 written by Robert
F. Dorr and Brian C. Rogers. See page 89 for a description of the
receipt and authentication of an emergency war order onboard an
1. "The Hunt for Red October" by Tom Clancy; Naval Institute Press; 1984
(still in print); ISBN 0-87021-285-0. Pages 65-66 (hardcover) for EAM
information; and page 68 (hardcover) for "traffic analysis" fans.
2. "Arc Light" by Eric L. Harry; Simon and Schuster (his editor was also
Rhodes' editor on "Dark Sun"); 1994 (Aug); ISBN 0-671-88048-9. The
author gets to engage the Midnight Express (see the "Logic..." book)
and run his SIOP, in a probable pre-92 way though.
04 April 2005
(updating information published on 02 September 1998 and 30 March 2005)