HFGCS General Log

[UtilitySeattle]

11.175 USB 9/21/25 22:30 ASPEN AIR calling LETTERBOX to enter the net. Authenticates with BACH BICWC.

[autovon]

11175 kHz

14 October
OLIVE64 (RC-135) calling for r/c.  SAKE? answers

[autovon]

11175 kHz

20 October
HAVOC56 w/rc.  MAINSAIL answers.  Then practice phone patch. QSY to 11056 khz.  An absolute disaster of a phone patch attempt followed.  Seems to be USAF standard for HF communications.
EVAC176 w/rc (C-17).  MAINSAIL answers.
UNID aircraft attempting a radio check.  The operator not understanding that you can't talk while the radio is tuning.  Also speaking at an auctioneers pace seems to be the norm.  Needless to say, radio check unsuccessful.
MANSFIELD66 w/rc.  MAINSAIL answers 2 minutes later...by that time MANSFIELD was gone.
CONVOY3544 w/rc

21 October
HUSKER15 requesting current message traffic.  MAINSAIL replies with none.

[INTERNETFRIEND]

* On October 21, Global Thunder 26 commenced. Based on a NOTAM for Area 602 (over the GoA), could be expected to last until the end of Oct 30.
* As with October 19, an E6 assumed a pattern near NAS Oceana ([Oct 19], [Oct 21]) and requested another E6 go to "VICTOR MIKE". Whether that's a location or a frequency designator unknown (and if the latter, I suspect it would be UHF or otherwise, and the airborne E6 may have been in communication with an E6 stationed on the ground at NAS Oceana).
* As well, E6s used a myriad of additional frequencies. I won't find time to go through my recording and link to timestamps of all of them, but for E6-to-E6 comms they utilized CA, BB, and CE Windows, and also Z140; https://www.youtube.com/watch?v=PxkRgL9xm3o

I figured out Zulu 140 is 15046 kHz – lists of Zulu frequencies floating around online seem to be 20 or more years out of date. As of October 2025 I know for sure the following;

Code: [Select]

Z100 13907 kHz
Z120 13245 kHz
Z140 15046 kHz
Z150 9016 kHz
Z155 18387 kHz
Z225 12070 kHz
Z310 11494 kHz

[INTERNETFRIEND]

From ALE on 4721 kHz (happen to have it);

Code: [Select]

[2026-01-14 16:36:52 4721.00] [Sounding THIS WAS] [From: OFF] [His BER: 11]
[2026-01-14 16:41:35 4721.00] [Sounding THIS WAS] [From: HIK] [His BER: 15]

[INTERNETFRIEND]

2026 April 05

"Fax machine noise" on 8992 kHz at 03:38 UTC; https://www.youtube.com/watch?v=2FkzGH_qlCE

Up until this year, I associated this noise with E6B-to-E6B communications, as it was typically heard on the CE Window (9031 kHz) and/or other frequencies apparently reserved for E6B communications [example from 2023]. However, in February 2026, the signal was heard on 13200 kHz during communications between ANDREWS and WESTCOAST [link], suggesting that E6Bs do not have a monopoly on this type of broadcast. (It also suggests that reports in late 2019 and early 2020 that 13200 kHz was no longer being used by the HFGCS were premature.)

This April 5th broadcast might be from a Mercury E6B which is not appearing on flight radars. Or, it might be a broadcast from ground stations during an otherwise quieter weekend on the HFGCS. (It is the Easter weekend.)

As suggested by more than a few people, including cryptomuseum.com's page on it, these "fax machine noises" are ANDVT.

[INTERNETFRIEND]

2026 April 08
On 8992 kHz; MAINSAIL heard attempting to contact BELLPEPPER at 18:02, 18:09. I did not hear BELLPEPPER respond; [YouTube link]

2026 April 09
On 8992 kHz; SPELLCASTER heard attempting to contact MAINSAIL at 12:56 for a radio check. MAINSAIL has SPELLCASTER faded and broken; [Twitter link]




The callsigns BELLPEPPER and SPELLCASTER are what I would generally allude to as being 'too long' – they are conspicuous.

[INTERNETFRIEND]

2026 May 06
12:45 UTC – C-130 SKIER91 heard attempting to contact MAINSAIL for a radio check on 13200 kHz. [ADS-B]

Not the most exciting capture in the world but follows additional incidental captures of activity on 13200 kHz. In 2020 Larry Van Horn reported that EAMs had stopped simulcasting on the frequency. EAM-like messages were captured earlier this year [link; YouTube], so it appears to still be a frequency that's part of the HFGCS.

[autovon]

6-2-26
11175
SKULL21 calling MUGBUG for radio check on new transmitter.    MAINSAIL answers but no response from the aircraft.
CHAOS43 calling for r/c.  MAINSAIL answers.