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Thread: OBOE as seen by the Germans

  1. #1
    Join Date
    Dec 2007
    Thanked 5 Times in 5 Posts

    Default OBOE as seen by the Germans

    Found this, it casts light on the German reaction to OBOE and their knowledge of the RAF units involved.

    "SECRET A. D. I. (K) Report No. 318/1944

    1. Attached is a translation of a paper issued by the General
    der Flakwaffe on 24th May 1944 concerning the British 'Oboe'
    procedure - called by the Germans the Boomerang.
    2. Apart from showing that the enemy understands the working
    of 'Oboe' the report is of interest as it indicates the lines
    on which German defence was concentrating. Night-fighters are
    dismissed summarily and the main hope is that, by knowing the
    approach course, the height and the speed of the attacking
    aircraft, the Flak defences must be concentrated near the bomb
    release point so as to produce a "Vernichtungsfeuer" by which
    success was certain. The report also hints that, since the
    German knew the 'Oboe' frequencies, radio counter-measures
    were in hand.
    3. One other point of interest is the high standard of the
    plots of aircraft attacking on the night of 2nd February 1944.
    This Sketch of is reproduced as Appendix II.
    4. The original document has been passed to A.D.I.(Science).
    A.D.I.(K) S.D. FELKIN
    29 June 44. Wing Commander

    ("TOP SECRET")
    Oberkommando der Luftwaffe Bernau b/Berlin d.24.5.1944
    Tel.: Berlin 56 40 76 App.:122
    General der Flakwaffe Bernau 814 u.815 od.üb.
    (General der Flakausbildung) L.V. 12.
    Az. 79 m Nr.0236/44 g.Kdos.(A/C)
    Number of Copies: 250.
    Copy N°: 79.
    Subject: Combating "Boomerang" Aircraft.
    Attached are instructions for dealing with
    aircraft attacks using the Boomerang procedure.
    In view of the importance of defence against this
    new method of attack adopted by the enemy it is imperative
    that all units be instructed in the Boomerang procedure and
    that counter—measures are adopted on the lines laid down in
    the attached instruction.
    Subsequent observations and experiences are to be
    reported to the General in charge of A.A. defences.
    All independent Flak Groups as well as interested sections of
    O.K.L., O.K.H., O.K.M., SS-Führungs-Hpt.-Amt, Höhere Kdre.,
    Flakersatzdivision General der Jagdflieger,
    Generalnachrichtenführer, General d. Kampfflieger u.
    GL/Flaktechnisches Amt.
    (Sgd) v. Axthelm.
    ("TOP SECRET")
    Encl. To: OKL – Gen.d.Flakwaffe
    Nr.0236/44 g.Kos. (A/C)
    Dated 24/May/44.
    A. General.
    Recently, nuisance raids have been developing more and
    more into high altitude precision attacks against pin-pointed
    targets (particularly important industrial complexes) by means
    of a special navigational procedure known as the "Boomerang"
    procedure. So far, "Boomerang" attacks have only taken place
    at night on the Rhine-Westphalian industrial area, Aachen and
    Osnabrück, airfields and railway stations, in the area of
    Luftgau Belgium/N. France, Paris and targets in Brittany.
    The "Boomerang" aircraft employed were Mosquitoes belong
    to 105 and 109 (B) squadrons, stationed at Marham. Immediately
    after take-off the aircraft climb to the prescribed attacking
    height of 8,000 to 11,000 metres, with a view to checking wind
    The enemy is carrying out on an increasing scale his
    precision attacks and pathfinder technique using the
    "Boomerang" procedure. It is clear from the increase of
    activity that the enemy is constantly expanding his
    "Boomerang" organisation and improving the technique. An
    expansion of these attacks on further targets with ever
    increasing effect is the result.
    It is therefore essential to bring to bear everything in
    our power with a view to combating "Boomerang" aircraft. The
    basic principle is that aircraft must be shot down.
    B. The "Boomerang" procedure.
    The "Boomerang" procedure is the most accurate method of
    remote control at present known. It consists of controlling
    aircraft by means of Radar stations located in S., S.E. and E.
    England. These stations work together in pairs of which one is
    the main station, and passes navigational signals to the
    aircraft. One signal from this station indicates the course to
    the pilot whilst the other is for the bomb-aimer to release
    the bombs. (see App. 1).
    The aircraft to be controlled flies under its own control
    to an agreed point, where the remote control takes over. The
    aircraft is then directed by W/T to the turning point, which
    is on an arc centred on the Radar station in England and
    passing through the bomb dropping point. Constant corrections
    from the ground station in England keep the aircraft on its
    course (see App. 1) but in spite of the great accuracy of
    measurement deviations up to 300 metres are possible.
    The total time required for the target approach is 8 to 15
    minutes. As soon as an aircraft passes over the target, the
    next one is taken over by control. The time interval between
    attacking aircraft is frequently reduced by attaching several
    uncontrolled aircraft to one controlled aircraft, or by using
    further pairs of Radar stations. The uncontrolled aircraft aim
    their bombes on ground or air markers. The approach to targets
    East of England is made from a N. - S., S. - N. or S. – W.
    direction. Targets South of England are approached W. - E. or
    E. - W. The course depends upon the relationship of the two
    Radar stations to one another.
    Unless there in a disturbance by a jamming station the
    final phase of the line of approach becomes an arc centred on
    the ground control station in England and passing through the
    objective to be attacked.
    It has been observed that simultaneous flights to
    different objectives on a N.- S., S.- N. as well as S.- W. and
    N.- E. courses, have been carried out, which proves that the
    enemy has already set up several ground stations.
    The range of this system is limited by the curvature of
    the earth and for a flight at a height of 9,000 metres, the
    range is between 400 – 450 km. The bombing accuracy depends on
    the reading and measuring accuracy of the ground station in
    England. The accuracy is within a square of approximately
    .5 km. by .5 km.
    So far, the followings types of "Boomerang" attacks have
    been made:-
    a) Single "Boomerang" aircraft.
    b) One "Boomerang" aircraft followed by 2-5
    uncontrolled aircraft.
    c) "Boomerang" aircraft as Pathfinders for a
    following bomber force.
    d) "Boomerang" Pathfinders as decoy marker flaredroppers
    and "window" aircraft. (Translator's note:
    the German text is ambiguous. The word is
    "Scheinmarkierer" which may mean decoy or
    illuminating markers. The subsequent context
    suggests the former).
    The "Boomerang" Pathfinders at first saturate the
    approach and target area with "Window", then place light
    markers over the target. The bomber stream then follows up
    immediately on the "Boomerang" course.
    C. Counter-measures.
    The following take part in "anti-Boomerang" attacks:
    a) Night fighters.
    b) Radio jamming service
    c) Flak.
    I. Our own Mosquito night-fighters (sic) have not had any
    worth-while successes in shooting aircraft down prior to the
    bomb release or to the commencement of the Pathfinder activity.
    Over a period of time, however, night-fighters should be more
    successful, provided high flying aircraft are employed.
    Uncontrolled night-fighting with the aid of search lights
    is possible if our own fighters are high enough and in
    sufficient numbers in the waiting area over the Flak zone.
    Because of vapour trails, it is possible to pick out highflying
    aircraft by searchlights.
    II. The radio jamming service has appreciated the principles
    of the "Boomerang" system and has set up jamming stations. It
    is possible to force part of the approaching aircraft off the
    approach line by jamming. However, the enemy soon recognises
    the disturbance and can change over to a pre-arranged
    alternative frequency. The radio jamming service has already
    met with success, but is still limited in its effectiveness.
    III. The main burden of defence, now as before, rests with the
    Flack. For the successful execution of the "Boomerang" system
    conditions must be fulfilled:-
    1. The attack must take place at a constant height of
    about 8,000 - 11,000 metres.
    2. The target approach must follow a fixed course for
    several minutes. (Course for every objective known).
    3. The ground speed must remain constant throughout the
    approach. (140 - 180 metres/s.)
    These known and partly constant target factors constitute
    a great weakness to the enemy. In addition the Mosquito,
    because of its wooden construction, is highly vulnerable to
    well-directed Flak.
    If, in spite of these favourable conditions, the Flak has
    only so far obtained little success, the fault lies in the
    increased factor of error when engaging targets at great
    heights, and also to the high speed of the Mosquito.
    On the other hand, the courses flown at the moment are
    well-known. This factor, together with the known target
    heights and target speed, enable the point of bomb release for
    each individual objective to be calculated accurately and in
    advance. These known facts, combined with the total fire-poor
    of all batteries within reach of the bomb-releasing area,
    should produce a successful "Vernichtungsfeuer" (annihilation
    fire) and prevent accurate bombing and lead to aircraft being
    shot down.
    D. Methods of Shooting.
    1.) The shooting method employed on principal is
    annihilation fire.
    2.) Provided that:
    a) The course is known,
    b) The target approach is fixed and confirmed by the
    Malsi Flak Calculating instrument.
    c) It is known with certainty that our own radio
    jamming does not result in the deviation of the
    enemy aircraft from its course and that the speed
    and height remain constant. This contradicts
    L.Dv.400/4b und VER-Flak 18 Ziff.11)
    3.) If the precise plotting is difficult, the following
    measures are to be taken:
    a) The track is to be set in accordance with the
    known value.
    b) The ground speed is to be obtained and passed on
    by the Flak transmitter. In the absence of this
    data, action is to be taken on the basis of
    previous experience. (Translator's note: in other
    words, use your own brains).
    c) Height is to be obtained from accurately adjusted
    Radar and is to be passed over the Flak
    4.) With reference to the manner, in which "Boomerang"
    coursers are to be obtained for individual
    objectives, Commands will contact Luftgaukommando VI
    with a view to ascertaining the courses for their own
    particular area.
    E. Tactical Employment.
    Suitable steps must be taken in the event of a change in the
    direction of approach of "Boomerang" aircraft, and if possible
    one to two batteries (special Eis. batteries) will be brought
    into the probable direction of approach for immediate action.
    F. Counter-measures.
    The following is to be noted when combating "Boomerang"
    1.) Most accurate alignment of the respective batteries
    (adjustment of instruments and guns, calibration of
    direction-finding apparatus, re-checking of ballistic
    correction of the moment in order to eliminate the
    meteorological factor).
    2.) Blocking together of the movement of target values:
    a) Set course for known value.
    b) Determine ground speed and height from previously
    emplaced batteries over Flak transmitter.
    3.) As far as possible the Trupp should be provided with
    uniform ammunition (as few different batches as
    possible); calibration shoots should be carried out
    with this ammunition and muzzle velocity
    determinations with (?special) calibration ammunition
    should be avoided.
    4.) Accurate meteorological reports must be obtained
    every two hours for heights up to 11,000 metres.
    These must be actual and not extrapolated. Contact
    must be made with the nearest airfield.
    5.) Charge temperature should is periodically determined
    by means the two specially equipped cartridges
    (Messcartuschen) placed in the ammunition dump.
    6.) The ammunition used for checking drill time should be
    carefully controlled and the error should be
    7.) Preliminary practices should be made along the known
    lines of approach by means of special fire control
    tables prepared for this purpose. Test shoots should
    be carried out using intervals of one second. (FAS I
    will supply fire control tables for "Boomerang").
    8.) All actual "Boomerang" courses should be charted on
    the Malsi plotting table as a check against the
    actual plots. (See Appendix II).
    A systematic research of shooting at great heights,
    having due regard to the available ammunition has
    been inaugurated. Results are to be expected shortly
    and until then all existing orders and instructions
    hold good. In order to keep counter measures apace
    with the enemy's intentions, it is essential to
    inform higher quarters of any new observations made
    during "Boomerang" attacks. The Luftgaukommando and
    Divisions are instructed to report regularly their
    experiences of "Boomerang" counter-measures to the
    General der Flakwaffe."

  2. #2
    Join Date
    Nov 2007
    Reading, Berkshire, UK
    Thanked 17 Times in 17 Posts


    Bruce, Tks for the sight of that!
    Fascinating document!
    Clearly, their SIGINT was of a very high order!
    We were lucky that the complexities of their administrative procedures, the “in-fighting” between various departments, and the poor high-level political direction of the war effort meant that “They” lost WW2, rather than “Us” winning it? Or is that overstating the case?
    Peter Davies
    Meteorology is a science; good meteorology is an art!
    We might not know - but we might know who does!

  3. #3
    Join Date
    Nov 2007
    London, Ontario, Canada
    Thanked 2 Times in 2 Posts


    Thanks for posting that Bruce, its very interesting reading. The Germans apparently designated two squadrons of fighters to deal with the Oboe Mosquitos in the summer of 44- From
    “for the defence of the Ruhr area a new approach was tried in August 1944. 6/JG 300 at Rheine was equipped with a mixture of Bf 109 and Fw 190 the latter fitted with FuG 217 Neptun, and 1/NJGr 10[B] with Bf 109G-6 AS was deployed at Rheine and Bonn-Hangelar”. I don’t think they were very successful, very very few Oboe Mosquitos were shot down by fighters, flak was their main danger. Most Oboe ops were at 28,000’ to 34,000’ and it took the fighters about 30 minutes to reach that height and the Mosquitos would have gone 150 miles in that time.

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