In 1943, the British intecepted an encrypted radio message sent from an airplane. Can a reader decipher it?

Looking for another interesting video to watch during the corona down time? David Oranchak’s latest Let’s Crack Zodiac webinar is certainly a good choice.


An intercept from 1943

Speaking of good choices, let’s now look at something I have found and chosen on Reddit. It’s a dispatch from the Second World War sent to Bletchley Park, where the British had concentrated their military codebreaking activities. As is well known, the specialists at Bletchley Park not only deciphered hundreds of thousands of German Enigma messages but also successfully attacked countless ciphertexts created with other machines or with manual methods.

The said dispatch from WW2 was published by a Reddit user named StalkerSchuhart in the Subreddit codebreaking already two years ago. Apparently, the cryptogram it contained was never solved. Here is it:

To my regret, a few passages in this letter are blackened. Nevetheless, it can be seen that the content is about an encrypted radio message sent from an unknown aircraft to an unknown base station in 1943. Here’s a transcript of the ciphertext:

39715 92953 13200 86129 51788 93871
84287 00611 98160 09494 51732 30474

In addition, a line with the following content can be read:

DTG: 120229Z NCR 3879 3 11 49

Considering that the Germans were the main war opponent of the British in WW2, it seems likely that this message was sent from a German airplane – but we can’t be sure.


Can it be deciphered?

As far as I know, German aiplanes didn’t use cipher machines for encrypting their radio messages – neither the Enigma nor others. The fact that the ciphertext consists of numbers doesn’t suggest that an Enigma was employed anyway.

So, which other encryption system may have been used? In my view, a codebook code is a promising option. Each of the five-digit groups might represent a code group taken from a codebook. Perhaps, the code is super-encrypted, for instance by adding a number to each group.

I’m afraid that a message of this kind can only be solved if the codebook is known. The best online sources for codebooks I’m aware of are the web-sites of John McVey and Satoshi Tomokyo.

Of course, it’s also possible that this cryptogram has already been deciphered and that the solution is availabe somewhere.

If you know anything about the background of this WW2 dispatch or if you can even break the ciphertext, please let me know.

Further reading: WW2 codebreaker Alan Turing to be the face of new British £50 note


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Kommentare (11)

  1. #1 Thomas
    20. Mai 2020


    I read the year as “1948” instead of “1943”, but it`s quite blurry on my screen. Remains the question when the name GCHQ (Government Communication Headquaters) came into use: According to the GCHQ website, this was the case in 1939 beginning with WW2. According to Wiki not before June 1946, during WW2 it was called GC&CS (Government Code and Cipher School). If the document is from 1948, there is no evidence that it might have been an intercept of a German message.

  2. #2 Thomas
    20. Mai 2020

    If the telegram was from 1948, I think the message was intercepted in Bletchley Park and forwarded to the GCHQ in Cheltenham.

    As for the plaintext abbreviations:
    DTG ist the Date-Time Group, NCR was a communications indicator, e.g. used in telegrams by the US (

  3. #3 Ralf Buelow
    20. Mai 2020

    According to Richard C. Aldrich’s “GCHQ” book, the term was used as a cover name for Bletchley Park since 1939 and was formally adopted for the service on 1 November 1948. I also read “1948” – please compare the digit with the larger 8s in the lines underneath.

  4. #4 Thomas
    20. Mai 2020

    Moreover, the last 3 numbers of the DTG probably mean Nov. 3, 1948 or March 11, 1948 (the first part standing for the time of day).

    According to the National Archives website, the name “GCHQ” was adopted in 1946:

    Hence I´m pretty sure the message was post-WW2.

  5. #5 Gerry
    20. Mai 2020

    The DTG code starts with the time 12:02:29, where Z stands for UTC. Date in DTG is in the form of D M Y, so it’s the 3rd of November 1948. The Message was intercepted already in October, as the blackened month is only 7 letters long, whereas November would have 8.

  6. #6 Chris Christensen
    20. Mai 2020

    One possible connection … .
    A USAF B-29A photo reconnaisiance aircraft departed RAF Scampton at 1015 on 3 November 1948 enroute to RAF Burtonwood. The aircraft crashed onto the moors near Higher Shelf Stones just short of its destination. All the crew were killed. No reason for the crash is known.

  7. #7 Gerd
    20. Mai 2020

    I think it must be 1948, even if the picture is blurry, compare the shape of the “3” used in the ciphertext. The “3” is very different from the “8”.

  8. #8 Rich SantaColoma
    20. Mai 2020

    From the comments, and I agree, this probably was post War, 1948. I would wonder, then, how they knew or suspected it was an aircraft that did the transmitting, especially if it were over Great Britain. I mean, just post-War I can’t imagine there was much mysterious aircraft traffic going undetected over Britain.

    And with no relating of them seeing nor tracking the movement of the craft, and without a designation of the frequencies used (although any frequency could be used from an aircraft or ground, of course), I would wonder if this could have been a “numbers station” broadcast that was intercepted. And these stations did and do often use five digit numbers, and one time pads.

  9. #9 Thomas
    20. Mai 2020


    Maybe it was possible to make out an aircraft as the source by direction finding methods of the British Y stations? ( If they were capable of detecting submarines as radio sources and determining their position, probably this also worked with aircrafts.

  10. #10 Klaus Schmeh
    20. Mai 2020

    John Reade via Facebook:
    Your website is always a great source of fascination – even more so as we are all under lock-down. Thank you so much.

  11. #11 Karo
    30. Januar 2021

    Date Time Group
    wird folgendermaßen gelesen:

    120229Z = 12. Tag und 0229 Zulu Zeit

    stände dort ein A wäre es Alpha bzw. Winterzeit und B dementsprechend für Bravo bzw. Sommerzeit.
    Allerdings fehlt bei der DTG nach dem Z noch der Monat in 3 buchstabiger Abkürzung und das Jahr
    Beispiel: 301419Ajan21 würde für den 30. Januar 2021 um 1419 Uhr Winterzeit stehen