What is an Emergency Action Message?

Tune a shortwave radio to 11175 kHz in upper sideband and wait. Sooner or later — usually sooner — a voice will read a string of characters in the phonetic alphabet: “November four tango seven whiskey lima…” It will read the string, repeat it, and sign off. That is an Emergency Action Message.

The network

The broadcasts come from the High Frequency Global Communications System (HFGCS), a U.S. Air Force network of ground stations that provides worldwide HF radio coverage. Its best-known frequencies are 8992 kHz and 11175 kHz, with others in the 4, 6, and 15 MHz ranges. The same message is broadcast simultaneously across the network's frequencies, so hearing any one good frequency means hearing the traffic.

The messages

Publicly, this much is documented by hobbyist references like priyom.org and long-running military-monitoring guides:

  • EAMs are among the most common broadcasts on the network — heard daily, around the clock, year-round.
  • A typical message is a string of a few dozen phonetic characters, read twice.
  • Messages are often rebroadcast — the same string heard again minutes or hours later.
  • A related broadcast type opens with “Skyking, Skyking, do not answer” — shorter, and by reputation more urgent.

The part nobody can read

The content is encrypted. The characters you hear are ciphertext, and no one listening — hobbyist, journalist, or us — can decode what any message means, who it is for, or whether it is routine or remarkable. Most traffic is widely assumed to be entirely routine: tests, drills, administrative traffic. The interesting thing about EAMs was never the content. It is the texture: a system that speaks constantly, in public, and says nothing anyone can read.

That is also why this hobby exists at all. The broadcasts are transmitted in the clear, worldwide, on known frequencies — listening is exactly as legal and exactly as old as shortwave listening itself, and the encryption is the reason the system can afford to be public.

Go deeper

Missileer is a desk monitor that listens to HFGCS around the clock and lights up when a real EAM goes out — the message rendered as it was heard, character by character. See Missileer →