The most common type of messages you will hear over the HF-GCS are Emergency Action Messages and Skyking messages, though the HF-GCS has many other uses. We’ve cataloged a few interesting and unique messages with explanations here, sometimes only the Primary HF-GCS station (11175 kHz) will contain some types of these messages. Please feel free to contact us to contribute anything else you’ve found.
EAMS are typically 30 characters long. This one is 215 characters long! There have been even longer messages than this before as well.
Although the HF-GCS is most commonly used by the USAF, sometimes other comms can be heard. This is in French, other times you can hear Italian, Portuguese, and others. [Recording by: vonAnsbach]
Sometimes, messages have an address for a region. In this one, the message is sent for “Region Alpha” and “Region Charlie”. [Recording by: vonAnsbach]
The HF-GCS also has a phone patch service which allows direct voice communications between ground stations and airborne units. This service is for unclassified communications only. In this recording Lion444 is requesting a phone patch to a German AFB from Mainsail. Looks like they didn’t get an answer.
This is a message for SKYMASTER – which is the collective callsign for all USSTRATCOM airborne command units. In this message they send 3-Figure phonetic groups. [Recording by: redanblacattack]
Sometimes the operator will ask to disregard their last message. In this one, the operator asks to disregard his last Skyking message.
This is a rare, high importance message only heard one time on the HF-GCS, where a message was transmitted in blind. The operator also included the diplomatic clearance for the receiver. “Disguise” transmitting blind to Melon 68, and the message was also repeated 3 times. The operator asks for their acknowledgement of the message as well. [Recording by Ary Boender, Numbers & Oddities]