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Thread: Resolving discrepancies on Routes to Bohlen and Chemnitz, March 5/6, 1945

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    Default Resolving discrepancies on Routes to Bohlen and Chemnitz, March 5/6, 1945

    I’m struggling to resolve a discrepancy I have found with the routes to Chemnitz and Bohlen, March 5/6, 1945. The Form "B" and 100-Group records indicate that the force to Bohlen and Chemnitz used a common route all the way to TP 5138 N by 1132 E. The force to Bohlen next turned to TP 5135 N by 1206 E, before turning to Bohlen, which I have as 5111 N by 1223 E (see attached document on the oil plant). The Chemnitz force, turned from TP 5138 N by 1132 E to TP 5130 N by 1240 E, before turning to Chemnitz which I have as 5050 N by 1255 E.

    I have converted “minutes” to “decimal degrees” for these coordinates, converted to KML and have uploaded them to Google maps. The Bohlen TP 5135 N by 1206 E is ABOVE (north of) the route for the force to Chemnitz. This does not make sense if you don’t want collisions. The maps I have seen show the first turning point towards Bohlen as BELOW (south of) the route for the force to Chemnitz.

    http://lancasterbombersinfo.ipage.co...ile/index.html (Pages 21-22)

    I have the night raid reports for this night as well as the 100-Group Charts and they consistently show the Bolen force as turning South after the northern most turning point.

    https://www.google.com/maps/d/u/0/ed...H_&usp=sharing

    However the attached record of the route for this trip shows the lower TP as correct.

    https://digitalarchive.mcmaster.ca/i...acrepo%3A81931

    Peter Hoare was a navigator with 5-Group and was on the trip to Bohlen and uses this route as an example of Navigation during WWII. He records a “northernmost” turning point of 5152 N by 1130 instead of 5138 N by 1132 E (on page 211 of his paper).

    Something isn’t right with the records here, and I wonder if anyone has looked into this in detail?

    Jim
    Last edited by JDCAVE; 16th May 2021 at 19:03.

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    Default Re: Resolving discrepancies on Routes to Bohlen and Chemnitz, March 5/6, 1945

    Jim, I will have a look over the next couple of days and get back to you. Regards, Terry

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    Default Re: Resolving discrepancies on Routes to Bohlen and Chemnitz, March 5/6, 1945

    Thanks Terry. I have had a discussion with a member off-line and we have concluded that the "Turning Points" are supported by multiple records. However, the Chart shown in the Bomber Command Night raid report (link above) appears to have been "mis-drawn". The first "Bohlen" turning point, after the two forces separated, is above the route to Chemnitz, not below, as drawn in the BCNR chart. As the two forces are separated temporally (The Bohlen force followed the Chemnitz force), this is not an issue, which would otherwise could have resulted in collisions between aircraft from the two forces.

    Jim
    Last edited by JDCAVE; 18th May 2021 at 19:06. Reason: Clarification

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    Default Re: Resolving discrepancies on Routes to Bohlen and Chemnitz, March 5/6, 1945

    Jim, And just when I thought I had solved the issue. It would be great to see a Bohlen 441 separate from Peter Hoares'. Back to the drawing board. Regards, Terry

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    Default Re: Resolving discrepancies on Routes to Bohlen and Chemnitz, March 5/6, 1945

    In a nutshell,

    all written references we've seen (Forms B, Interception Tactics & Night Raid Reports, BC Loss Cards) show the following segments of the two routes, starting at the last common waypoint:

    Chemnitz - 51 38 N, 11 32 E - 51 30 N, 12 40 E - Chemnitz

    Böhlen - 51 38 N, 11 32 E - 51 35 N, 12 06 E - Böhlen

    As Jim says, if these waypoints are plotted from the common originating point of both routes (51 38 N, 11 32 E), then the Böhlen track heads slightly north of the Chemnitz track before turning south-eastward.

    However, every cotemporary raid plot map I've seen (Interception Tactics & Night Raid Reports, Raid Analysis Report, Pearl/Zip/BMP Report) shows the Böhlen track heading south of the Chemnitz track. We can find no obvious reason for this divergence with the written route coordinates. One raid plot map (attached to the Raid Analysis Report) is done on a standard Caption of the Aircraft map, so it's possible to estimate the waypoints drawn on the map against the scales along the sides of the map. This particular raid plot map appears to show:

    Chemnitz - 51 38 N, 11 32 E - 51 25 N (not 51 30 N), 12 40 E - Chemnitz

    Böhlen - 51 38 N, 11 32 E - 51 26 N (not 51 35 N), 12 06 E - Böhlen

    The Peter Hoare track for Böhlen differs yet again and follows a similar course to the Chemnitz route before turning due west to attack Böhlen. I can only presume that the No. 5 Group 'Pathfinders' from 83 Squadron flew routes different from the main briefed route so they could approach the target from different directions.

    Cheers

    Rod

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    Default Re: Resolving discrepancies on Routes to Bohlen and Chemnitz, March 5/6, 1945

    Rod has covered our off-line discussion. The only point I can add is, F/O Seale navigator with my dad on the op to Chemnitz, did not update the Flight Plan section of the Navigation Chart for a revision at 5130 N to 5125 N so we really don’t know whether this revision actually took place. At the time/point they steered to this TP he didn’t actually record the details of the TP, as he had done on previous and succeeding TP’s. The “strain” is evident in the logs as they get closer to the Taget Area.

    Rod: he records another “kite going down” as they turned SW (5040N 1300E) after leaving the target area.

    Jim

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    Default Re: Resolving discrepancies on Routes to Bohlen and Chemnitz, March 5/6, 1945

    Jim, I had come to the same conclusion as Rod re the the southeasterly turn for Bohlen at TP I with almost exactly same coordinates. I also found it interesting that a height restriction was imposed on both the Chemnitz and Bohlen aircraft as they departed the targets, see 6 Gp Form B, Note VI (c). I would have expected to see a similar height restriction applied if the Bohlen aircraft were going to intersect with the Chemnitz aircraft between TP I and TP J. As regards the 2038 entry re fighter and other seemingly miscellaneous entries, Russell Steer, a 405 Sqn nav, notes that it was the nav's responsibility to note in his log information from the gunners re "things seen". Regards, Terry

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    Default Re: Resolving discrepancies on Routes to Bohlen and Chemnitz, March 5/6, 1945

    Terry: the two forces were separated in time and therefore location, until the return trip, where the Bohlen force passed beneath the that of the Chemnitz, approximately at Schoneck. Note that the Seale’s records indicate they were screaming along at 220 MPH. And yes, evidently 419 Squadron was still using MPH as the ASI units were marked in MPH. Bomber Command was transitioning to Knots, but the holdup was that they had to swap out the older ASI units with newer models marked in Knots. There is a reference in the 6-Group ORB appendices about this.

    Jim

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    Default Re: Resolving discrepancies on Routes to Bohlen and Chemnitz, March 5/6, 1945

    Jim, I spoke to the "One Night in December" guys and there suggestion is: TMT = To Maintain Track, and TRT = To Regain Track. They acknowledged that they hadn't seen the abbreviations before so it was a guess. As to the track for Bohlen: I have asked the museum at Hendn if they have a 441 for the Bohlen raid; awaiting an answer. Regards, Terry

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    Default Re: Resolving discrepancies on Routes to Bohlen and Chemnitz, March 5/6, 1945

    Hi Terry,

    my understanding is that a height restriction on the outward route was possibly unnecessary since there was roughly 33 minutes of separation between the heads of the Chemnitz and Böhlen streams, based on the times recorded for each stream first crossing the continental coast outward (18:10 hrs and 18:43 hrs, respectively). The bombing times of the Chemnitz force indicate the stream was roughly 31 - 35 minutes in length, if that makes sense.

    Also, the Böhlen stream had to be at bombing height (mostly between 10,000 - 13,320 feet) by 51 38 N, 11 32 E. No. 1 Group on Chemnitz, for example, had to be at 15,000 - 19,000 feet in the same area, meaning there was likely altitude as well as time separation between the two streams at the proposed crossing point of the two tracks near 51 35 N, 12 06 E.

    Cheers

    Rod

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