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Thread: Co-ordinates for code ZCAH2207 in March 1941

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    Default Co-ordinates for code ZCAH2207 in March 1941

    Hi all,

    I am looking for help with decoding of code ZCAH2207 into co-ordinates used on 21. 3. 1941 while returning from Lorient, i.e. I suppose some place over France or Over the Channel.

    TIA

    Pavel
    Czechoslovak Airmen in the RAF 1940-1945
    http://cz-raf.webnode.cz

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    Hi

    I don't recognise that coordinate format but if it was just AH2207 it would be in the sea around 30 miles west of Bordeaux at 44 57 50N, 2 27 23W.

    The reference AH is within the "French Lambert Zone 3" area - possibly the "ZC" refers to that.

    ATB

    Mike
    Last edited by lancasterlm342; 11th February 2019 at 09:17. Reason: Additional info

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    Hi Mike, thank for your effort.
    I know that two letter always stands for degrees and two numbers for minutes.
    Ross has helped me in the past to decode some of those for some CC Squadrons but as the letter combination differs time to time it is difficult to find correct answer.

    Pavel
    Czechoslovak Airmen in the RAF 1940-1945
    http://cz-raf.webnode.cz

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    Hi Pavel

    The two letters refer to a 100km X 100km square and the numbers eastings and northings. This link is a very useful resource as it shows where all the squares are and has a "coordinate converter".

    www.echodelta.net/mbs/eng-overview.php

    Hope this is useful - I have used it many times and it is very accurate.

    ATB

    Mike

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    Hi Pavel

    This appears to be the special alphanumeric codes assigned to Maritime and FAA squadrons.

    From notes I made when looking at 15 Group ORB a while back, in Jan’41 letters ZC equated to 49N and AH to 04W. Based on the premise of the codes not changing for some time and that the sighting was always with a latitude south and longitude west of the target, this would give 49 deg 22 min N (49.366667 decimal) and 03 deg 53 min W (03.883333 decimal). I appreciate there is a gap of several weeks between the codes I noted and the date of your incident, so hopefully Ross might be able to pass comment or have some more timely data.

    You don’t say the squadron or the subject being reported, however if it is off significance then it should be reported in the relevant Group ORB who might mention the code ‘in clear’ in the accompanying narrative. Possibly also in the appropriate Station ORB.

    Kind regards
    Pierre

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    Mike - this is different scheme than the converter is able to convert.

    Pierre - thank you for your informative post. I agree that those dates are so close that the codes may have the same meaning at the time.
    I have only one question - if you stated AH was 04W why do you decode the code as 03 deg 53 min W and not 04 deg 07 min W as I suppose it should be?

    There is no secret with the squadron - it was 311 Sq so No. 3 Group as you have suggested. But as it was just a position noted by the navigator on the way back without anything extraordinary or any sighting, I am afraid it would not be noted in group ORB nor in the station ORB.

    Pavel
    Czechoslovak Airmen in the RAF 1940-1945
    http://cz-raf.webnode.cz

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    Hi Pavel

    For quite some time I always thought it was a case of working out the lat/long for the first four letters to get the degrees, then as you say adding the four numbers to the respective degrees to get the minute reading. The first time there was a warning bell about how the system worked was when I read this post http://www.rafcommands.com/forum/sho...tude-positions and the comment at #6. In map reading you always go across and up the grid adding numbers as you go to increase the accuracy of the grid reference, so it would be natural to think these codes worked likewise.

    By way of confirmation under the section about AIR 27 in the book published nearly thirty years ago, “RAF records in the PRO” by Simon Fowler, the same methodology is explained. If only I had bought a copy earlier!
    Using your enquiry as an example ZCAH2207 has translated on my assumptions as mentioned previously as 49deg 22min N 03deg 53min W. This means the site is bounded by northings 49deg=ZC and 50deg=KM and westings 03deg=DF and 04deg=AH. Using the rule of quoting the latitude south (ZC) and longitude west (AH) means the first pair of numbers are added to the latitude and the second pair deducted from the longitude.

    If I can work out a way of doing it I would love to be able to create a spread sheet which contains the all the relevant data to facilitate the looking up of a specific date. Then to see what codes were in use and what they would then translate into if you had an example such as above.

    Does ADM 186 yet hold this promised gem?

    As an aside you mentioned it was an operation by 311 Squadron. Being part of coastal command I have found that very often hidden away in the Group ORB appendices are the Form Green and detailed daily Narratives. These not only give details of the operation being ordered but also on occasion the routings taken to and from target.

    Kind regards
    Pierre

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    Pierre thank you very much for pointing out the older thread which I have missed and other sources describing the method you have used.

    Well it is quite surprising to me as my access to this code was always "degrees as important information has been coded, while minutes as less important were in numbers" so I was always using minutes 1:1.

    I have to check my sources as I think in some cases when comparing CC squadron/station/group ORBs sometimes one gives coded position while the other gives decoded position. So maybe I will be able to find some examples which would confirm on or the other method.

    As for 311 Sq - you are right but this is valid from May 1942 as September 1940 - April 1942 it served with the BC.

    Will be back if I will find something

    Pavel

    P.S. It is pity that Ross was not able to publish his next volume of CC losses as if I remember well he was planning to reveal there the mystery of this coding (partially at least)
    Czechoslovak Airmen in the RAF 1940-1945
    http://cz-raf.webnode.cz

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    Pierre, my sincere apology and BIG thanks for pinting me to the right direction.
    My memory is fading and as I have been decoding positions last time in 2013 I was wrong.
    Your are right how it should be counted what I can confirm also with several examples from the waritme records of 311 Squadron:

    16.8.42
    FNBK3502
    46N35 06W58

    7.9.42
    FNWY5505
    46N55 08W55

    9.9.42
    CVSU2530
    45N25 09W30

    Pavel
    Czechoslovak Airmen in the RAF 1940-1945
    http://cz-raf.webnode.cz

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