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.





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

  1. James E Bateman says:

    Started my navy career as a Signalman 1965. Got out in 67, and went back in 1979 straight to RM A School, San Diego. Already knew Morse (flashing light, semaphore, and flags). Graduated A School, and went to IMCO International Morse Code Operator school…It was a breeze since the navy taught me to type on a ROYAL typewriter, then over to Teletypes.
    Modern navy IMO…made a very serious mistake not using Morse anymore. What will they do when all of the Satty Comms go down? TOMATO CANS and STRING won’t work either.

  2. dcasler says:

    Thanks for sharing your memories!

  3. Thomas E. Peters Sr says:

    Wow. I was at Keesler AFB, MS as trainee Ground Radio Operator (Voice) – our class was the firs to not have to learn Morse Code. Wish they would have kept it going. After Keesler, I was a Radio Operator for the SAC Alpha Net @ Elkhorn, NE. 1970. July 70-71 I was at Cam Ranh Bay, RVN as a MARS Radio Operator @ AI8AC. Our station was the Gateway station to SEA (In country, Thailand and another country). We received MARSgrams from AK!AIR, Alaska MARS station via RTTY. We had to pass those messages via voice to the respective stations for their dissemination.
    I was also a Security Police Augmentee. So was pulled from MARS when the shit hit the fan.
    When returning to the States, the Air Force changed my AFSC to Administrative Clerk. 71-73 @ K>I. Sawyer AFB, MI. I was able to break free of the Admin Clerk there and got into the Tactical Communications Office as Acting NCOIC. The Air Force again needed my Radio knowledge at RAF Mildenhall, UK (73-76) working the Bravo Net. Same duties as I had at the Alpha Net but now in the European theater. I tried to get a Ham license while in the UK but could not get the Morse Code down. Came back to K.I. Sawyer again but the AF let me pick my AFSC. I chose Security Police – Law Enforcement. Held the positions of Patrolman and later Flight Chief.
    I got out in 1980 only to find Cops laid off all over the country. Bas move – also cheated out a retirement package.
    Anyway, got my Tech ticket as KE8BXO then my current General ticket as N8HIS.

  4. Goat Hogan says:

    Worked 1957 thru 1961 with P2V aircraft out of Rota. All messages identical except for aircraft last digit and last digit of Zulu time. At the end of a shift sit down and type all messages. Amazed the newbies. Things got tougher in 1965 when we started monitoring broadcasts.

  5. Nick Feasey says:

    INT ZBM I still you use this today. Ex R. Sigs.

  6. William A Arnold says:

    Was radio operator in Alaska for 4 years after training at Keesler. As someone already said things have changed a lot over the years. I still know the code and also have my hame rig in use regularly.. Licensed call sign WB5KRO using a kenwood xmtr.

  7. Paul J. (PJ) Menard says:

    Flew as radioman on the Distant Early Warning Line with the Navy in VW-12 and AEWBARRONPAC late 50s early 60s. All tactical communications was with CW.
    I only had one instance when I had to use ZBM2. Yankee and Zulu messages were piling up on my desk. After a brief pause the CPO in charge back at COMBARPAC got on the circuit. We got things done pronto. All with a J-38 on my end. It was a pleasure. Hard to feel sorry for the recipient of my ZBM2.

  8. Joe Clark says:

    As I noted many years ago, the Q signals dealt mainly with aviation and weather, not necessarily civilian use only. Military usage of the Z signals came later, but the Q signals were used by pilots so that they could get their messages out quickly and continue to concentrate on flying their aircraft.

  9. John M Cliff-G0WXU says:

    On a graveyard shift one night I was getting fed up with the Op at the other end sending IMI almost every line of text. I was sending traffic at approx 20 WPM. I was an instructor in CW and procedure so my fist was constant with no errors. Conditions on HF were good. I continued to re send has requested for quite some time but I was getting more and more frustrated at the “IMI” requests. That was it. I thought sod you. I sent ZBM2 on my next over and waited for a reply. I got AS AR. Then the supervisor at the other end got funny and sent a ti-raid of text at approx 30WPM. OK cleaver bugger I put my mates Bug Key in circuit and rapped off the fact that I had got traffic to send and clear with him. How long a shift is this going to be IMI IMI. Next communication was K. and I was able to clear the traffic with no more IMI’s. I think he must have stay’ed on circuit and thrown the other guy off.

  10. Best insult was ZBM2

    “Put a qualified operator on the circuit”

  11. Randall Walker says:

    What a walk down memory lane! Used to spend 12hr watches in Kodiak, AK (72-73) looking at this pub! I can still remember all the watch ops!

    Randy Walker, RM2, USCG

  12. Voytle Vernon Shackelford (Vern) says:

    I was an aviation radioman/gunner flying in OS2U Aircraft flying in the Aleutian IS. during WWII Squadron VS-49 and I remember that ZUG meant ‘I am forced to land or alight at”

  13. 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.

  14. Jim Huff says:

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

  15. 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.

  16. 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###

  17. 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.

  18. T. Lamberton says:

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

  19. 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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