ACP 131(B) Q-Signals and Z-Signals

ACP 131 Tabs

My old copy of ACP 131 is divided by tab markers for easy reference. It's version B, with Changes 1-5, and is dated in 1976. It provides both encode and decode for both Q and Z Signals. The Q-Signals are for civilian use and the Z-Signals for military use.

Q-Signals (e.g., QSL meaning “I confirm”) were in wide use during the days of radio telegraphy. Their meaning is universal in any language, which made it easier for radio operators in different nations to communicate. Although they’re still around (and ACP 131F is considered the authoritative source per Wikipedia), we hear only a smattering of them on the ham bands, mostly in the QRA – QRZ, QSA – QSZ, and QTA – QTZ series.

I’ve had this old document for decades. It’s an older version with Changes 1 – 5, with Change 5 dated 28 April 1976, which was just before I went into the Air Force, so I’m presuming I got it then. I put it here for its historical value, because it reflects current usage back then. The most up-to-date version can be found here at the DoD DTIC website.

I’ve organized this the same way my book is organized: using tabs. Also, accessing the book a little at a time makes each section download more quickly. Clicking on a link brings up the section in another browser tab. Once you close that tab, you should come back here.

Note that although this is a nice, clear, sharp scanned copy, the text is selectable and copyable.





7 Responses to ACP 131(B) Q-Signals and Z-Signals

  1. Martin Kempka says:

    ZZO ZWH when I was in the Navy as a Radioman stated to “rephase and try again”. I understand it later went to “ZYR-1 ZWH. I believe we use to have a US SUPP to the ACP 131. Been retired almost 22 years so not sure what it is now.

  2. Jim Huff says:

    As i recall ZZO was “try again”. As in “Rephase and try again” ZWH ZZO

  3. Dave says:

    Hi Tom, I’m wondering if ZZO was an “informal” signal, as the book lists no codes starting with ZZ. I looked in the updated ACP131 and found nothing there either.

  4. I have looked at a lot of the ACP 131 listings and wonder if I have really lost it!?

    I seem to clearly remember ZZO# An inexperienced operator is about to send signals using###

  5. Dave says:

    It looks like ZDL is not used for a question, but rather only as an “Answer, Advice, or Order.” It looks like it’s simply a “confirmation,” much like hams use “QSL” today. ZDL with the number 1 means “was omitted,” and ZDL 2 means “differs from text.” I can see how it could easily have been used as you describe.

  6. T. Lamberton says:

    What happened to “ZDL 1 and 2. USAF in late 60s and early 70s used ZDL2 for “Unable to xmit pictures?

  7. Lupe Torres says:

    You forgot:

    INT ZZZ – “Are you asleep”. Or, at least, that’s what we in the U.S. Navy translated that to when someone on the other end couldn’t “get it”.
    Thanks for the post. Brought back some good memories.
    Lupe Torres
    RMCS USN (Ret.)

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