F.T.P. 223A AND CB 04234 (A.C.I.)




This publication has been approved for joint use
in anti-submarine warfare and defense of convoy.



For the First Sea Lord of the Admiralty.
Admiral, U. S. Navy
Commander in Chief, United States Fleet
Chief of Naval Operations.


[This page was blank in the source document - HyperWar editor]









General 1
Support Group of One Nation Cooperating With Convoy Escort of Another 2-4
Special Instructions When a CVE is Present 5
Cooperation Between Convoy Escort and Shore Based Aircraft 6-7
Communications 8-11








1000. GENERAL.

  1. The two principal publications at present in use which contain doctrine as to escort of convoy are the United States Publication, U. S. Fleet Anti-Submarine and Escort of Convoy Instructions (F. T. P. 223) and the British Publication, Admiralty Convoy Instructions (C. B. 04234).

  1. The object of this supplement in amplification of the above two publications is to enable British and United States Air and Surface Forces to cooperate adequately in anti-submarine warfare and for the defense of convoys. Commanders of either nationality may find it convenient to use certain parts hereof when not operating with forces of the other.

  1. FTP 223A is to be used in all operations in U. S. Strategic Zone or in which U. S. Forces take part.

  1. When forces of the two nations are cooperating, only Combined or Limited Combined signal publications and procedures are to be used.





  1. Signal From Operational Authority.

    The signal made by the operational authority directing a support group to cooperate with an escort group shall provide each commander concerned with such information as may be necessary for them to effect a junction without delay and with the minimum use of radio. Items that normally should be included are:

    1. Designation of unit to be supported and its position, course and speed.
    2. Name, rank and seniority, if possible, of Senior Officer in each group and name of flagship. Number and type of ships in each group (unless this is already known).
    3. Convoy call signs.
    4. Frequency in use (if other than 2410 kcs.).

  1. Method of Homing.

    The Senior Officer of the joining group may request homing by operating "Q" signal stating the time of commencement and the frequency to be used. This signal can be made direct or through a shore station. In the latter case it should be in code.

  1. Command of Forces When Junction Is Effected.

    The Command of the Support and Escort Groups devolves on their own Senior Officers and normally all orders will be issued through such Commanders. Irrespective of seniority, the Senior Officer Support Group shall comply with the requests of the Escort Commander who should give general directions for the conduct of operations in defense of the convoy for which he is responsible.

  1. Exchange of Information on Joining.

    In order to facilitate the exchange of information on the Support Group joining, the following standard forms of signal may be used following a reference to this Article (BUSCI 2040):

  2. (From Escort Commander to Senior Officer Support Group.)

    1. Course and speed of convoy. Convoy time. Any stragglers.
    2. Zig-Zig in use if any.
    3. Intended alterations of course.
    4. Convoy escort stationing diagram in use.
    5. List of ships of convoy escort, their positions in diagram and call sign numerals.
    6. Night intentions.
    7. Commodores R/V for noon the following day.
    8. Names and convoy numbers of escort oilers and depth charge carriers present.
    9. Voice frequency in use if other than 2410 kcs.
    10. Any special orders regarding radio security including instructions regarding the use of radio for HF/DF intercommunication purposes.
    11. Any special instructions for the Support Group including action to be taken in the event of air attack in areas where this may be expected.


    (From Senior Officer Support Group to Escort Commander.)
    [There was no "L" or "M" entry in the source document - HyperWar editor]

    1. List of ships of Support Group and call sign numerals.
    2. Ships fitted HF/DF.
    3. Names of ships defective in the following:
      1. Surface warning radar.
      2. Sound equipment.
      3. Radio (voice).
      4. Anti-submarine ammunition (if below 50%).

    4. Remaining endurance in days of ship lowest in fuel or lubricating oil.
    5. Any special information.

  1. Method of Stationing Ships.

    Ships or groups of ships may be stationed by the diagrams given in F. T. P. 223 or A. C. I. according to which publication is in use. An alternative method which provides also for the stationing of ships in extended positions is by true bearing expressed in three numerals and distance in miles from center of front line of convoy. (Position ZZ) e.g., 123° ZZ 7.

  1. Observance of Radio Security.

    Except to pass traffic essential to the accomplishment of the assigned task, radio silence is to be observed unless restrictions are relaxed by the Escort Commander. Radio transmissions on frequencies higher than 50 mc/s are, however, permitted unless otherwise ordered.

  1. Sighting Reports.

    When sighting reports are made under conditions where it is probable the enemy sighted has knowledge of position of convoy or when necessity for speed outweighs security considerations, sighting reports may be made by R/T or W/T using voice code, plain language, or by using a special method of position as follows:
    . . . . . {True Bearing} . . . . . ZZ . . . . . {Distance in Miles} . . . . .
        Where ZZ is center of convoy front.

    When sighting reports are made under conditions where it is improbable that the enemy has located the convoy or when for other reasons security of position of convoy is required, the most secure Combined codes available shall be used.

  1. Precaution When Leaving Station at Night.

    Any escort leaving her assigned station or approaching the convoy at night should normally inform the Escort Commander by voice radio of her movements.

  1. Reports Concerning Encounters with the Enemy, Casualties, etc.

    The Escort Commander will be responsible for reporting all matters relating to the convoy, the convoy escort, and such ships of the Support Group as may be in close touch. It is not possible to lay down in these orders precisely what reports must be made, but the Escort Commander must observe the following general rules:

    1. He must comply with the requirements of the operational authority under whom he is operating.
    2. He must comply with the standing orders issued by his own National Administrative Authority provided that this does not conflict with the area orders regarding the use of radio.
    3. NOTE: It may often be possible to comply with the requirements of (a) and (b) in one report.


  1. Attack on a Submarine.

    In general, the attack procedure in all forms of surface attack on a submerged submarine is very similar. The following common principles are emphasized:

    1. The necessity for frequent and rapid exchange of target information by voice radio in plain language and/or visual.
    2. Except in the case of attack on a submarine known to be deep, (British creeping attack), the first ship to gain contact is the ATTACKING SHIP. She carries out this duty until her consort (British DIRECTING SHIP, U. S. ASSISTING SHIP) is ordered to become attacking ship.
    3. When more than two ships are present, ships other than the attacking and directing or assisting ship should with due regard to (d) below carry out operation OBSERVANT.
    4. The necessity for avoiding all forms of interference by wakes, H. E., foxers, or passing between the attacking ship and the target.
    5. When all ships lose contact, carry out operation OBSERVANT.

  1. Relative Bearings.

    Attention is called to the discrepancy existing between the two methods of expressing relative bearings in the two Navies:

  2. United States:   Bearings are expressed clockwise round the ship from right ahead (0° - 360°) and the word "relative" is always used after the bearing to distinguish it from a true bearing.
    British:   Bearings are expressed from forward to aft either side (0° - 180°). Red indicates Port side. Green indicates Starboard side.
    Example:   Red 70° = 290° Relative.

  1. Combined Submarine Attack Signals.

    Combined Submarine Attack Signals are to be found in CSP 1846.





  1. Command of Forces.

    When a CVE is operating with a convoy she will come under the orders of the Escort Commander.

    1. It is the duty of the Commanding Officer of the CVE to control all air cover, including fighter cover, in accordance with the general requirements of the Escort Commander.
    2. If more than one CVE is present, the Senior Commander will perform this duty. If, however, CVE's of mixed nationalities are present, the control of air cover is vested in the Commander of the CVE which is of the same nationality as the Escort Commander even though he be junior.

  1. Station for CVE in Convoy.

    When one CVE is allocated to a convoy a column is reserved for the CVE next to the Commodore's, in which there is only one ship - the leader. It is recommended that the CVE should take up the position of the third ship in this column.

    1. When more than one CVE is allocated to a convoy a number of rear positions in each of the adjacent columns to the Convoy Commodore's column should be left vacant for the CVE's to occupy. The positions taken up will depend on the number of CVE's, direction of wind, etc.

  1. Cooperation with MAC Ships if in Company.

    The flying operations of the MAC ship will be directed by the Escort Commander who will pass his air requirements to the MAC ship. It is important that the MAC ship should receive as long notice as possible of the required flying programme. The Escort Commander will keep the Convoy Commodore informed regarding his directions to the MAC ship. In determining whether conditions are suitable for flight the Escort Commander shall give due consideration to the recommendations of the Master of the MAC ship and if he disregards such recommendation he accepts full responsibility for the consequences of his decision.

    1. If a CVE is present, flying will be coordinated by the Senior CVE Commander in accordance with Article 3012.

  1. Communications.

    It is the duty of CVE's to act as a radio link between the aircraft they control and ships of the surface escort. The information should be filtered before retransmission in order to avoid congestion. If direct communication should be required between carrier borne aircraft and individual surface units, the CVE will order the aircraft in question to shift to the general air coverage frequency and will act as a radio link until intercommunication has definitely been established.

    1. Communication Linkage with Shore Based Aircraft.

      To the end that aircraft shall not have to fly over a convoy, visual linkage between CVE and aircraft will normally be via Escort Commander; radio linkage with or via CVE.

  1. Homing.

    Should it be necessary for a surface vessel to "home" on a carrier borne aircraft, the methods prescribed in Article 4080 are applicable.





  1. Signal from Operational Authority.

    It will be the normal practice for the operational authority to inform the Escort Commander of the air cover which will be provided. Items normally included in this signal will be:

    1. Number and type of aircraft.
    2. Time of arrival over the convoy.
    3. Radio call signs.
    4. Base frequency if other than 6666 kcs. day, 3925 kcs. night.
    5. Air coverage frequency, if other than 2410 kcs.
    6. If desired by the operational authority instructions to "home" may be included in this signal.

  1. Homing Procedure "B".

    Homing procedure "B" which is common to both F. T. P. 223 and A. C. I. will be the standard homing procedure. This procedure may be ordered by the operational authority or requested by the aircraft. Operating "Q" signals will be used, and the frequency on which ships are required to pass bearings will, if different from the air coverage frequency, be stated. British Escorts cooperating with British aircraft may transmit bearings to planes on 3925 kcs.

  2. Homing Procedure "C".
    1. When aircraft are unable to locate an independent merchant ship to be escorted, the aircraft shall transmit an encrypted "Not Met" report to the base. This report should be sent upon completion of the first circuit of the search plan.
    2. If the operational authority considers that homing procedure should be carried out, the aircraft will be notified. At the times directed by the operational authority, the aircraft shall transmit for two (2) minutes on 385 kcs., the war radio call sign of the ship to be escorted followed by the letter "A" and a number indicating the numeral relief of the aircraft, i.e., "A1, A2," etc.
    3. The Merchant Ship will break radio silence, transmit her war radio call sign on 375 kcs., and give the DF bearing on the aircraft. Ordinary "Q" operating signals will be employed. The naval authority ordering air cover for an independently routed merchant ship shall advise the vessel concerned by BAMS message of the estimated time of arrival or aircraft and shall direct ship to maintain watch on 385 kcs. beginning at a specified time.

  1. Recognition.

    Instructions for air/sea recognition are laid down in S.P. 02312(4) Aircraft Recognition Procedure. This is a combined publication.

    Attention is drawn to the instructions laid down in A. C. I. and F. T. P. 223 that the Escort Commander (during daylight hours) shall train a steady light on the aircraft in order to identify himself.

  1. Communications Air.

    Visual is the primary method of communication between ship and aircraft except where radio security conditions permit the use of radio.


    Radio communications will be by voice primary, key (M. C. W.) secondary, on the assigned air coverage frequency. The combined codes, prescribed for intra Air/Ship communication in the area of operations will be used, and in addition, the code words given in F. T. P. 223, Article 6097 and those marked with an asterisk in the British Convoy Escort Code.

  1. Aircraft Patrol.

    The type of aircraft patrol to be carried out shall normally depend on the nationality of the Escort Commander. Should the Escort Commander so desire he may however order any patrol regardless of nationality. If an aircraft is unable to execute any patrol ordered he will request another patrol, specifying the type of patrol he is able to fly under the prevailing conditions. It should be noted that aircraft covering a U. S. escorted convoy will have been briefed with the special patrol applicable to the relative speeds of convoy and aircraft. Such aircraft will report this upon arrival and will execute this patrol unless the Escort Commander otherwise directs.

  1. Sighting Reports.

    At first opportunity after a sighting and without delaying attack the aircraft sighting the enemy in the vicinity of a convoy is to report to the Escort Commander by voice or W/T (M. C. W.) on the air coverage frequency. This report is to be followed by W/T report to base as soon as possible. Reports are to be made in accordance with paragraph 2070.

  1. Method of using IFF to indicate an enemy sighting.

    On sighting the enemy IFF should be switched to stud 4.

  1. Method of homing Surface Units to A/C.

    Surface units will home to the enemy by any or all of the following methods:

    1. Bearings of shadowing aircraft taken by own Radar.
    2. Radar bearings of surface unit taken by aircraft and passed by voice.
    3. Homing on to W/T transmissions from aircraft.
    4. NOTE: In the case of (c) appropriate operating "Q" signal must be made to aircraft.

  1. Priority as to Attack.

    If both aircraft and surface craft are in position to attack, unless the surface craft is in position to ram, a submarine on the surface or submerged less than 15 seconds is primarily the target of the aircraft. All other submarines are primarily the target of surface craft.





  1. Radio Security.

    The orders for Radio Security will be given by the Escort Commander subject to any specific instructions issued for any area by the Operational Authority. General guidance regarding Radio Security is given in F. T. P. 223 and A. C. I.

  1. Radio Watch.
    1. 2410 kcs. is the standard convoy voice frequency. This frequency will normally be guarded by each group Escort Vessel unless the Escort or Support Group Commander orders otherwise.
    2. From the time of receipt of orders for a Support Group to join a convoy, a guard on 2410 kcs. is to be maintained in the Support Group and in the Convoy Escort.
    3. All ships which are equipped to do so shall guard 72.5 mcs. (Voice).
    4. The Escort Commander will detail Radio guards required by F. T. P. 223 or A. C. I. and local area orders.

  1. IFF.

    Shipboard IFF should be switched on, on the following occasions:

    1. Throughout dark hours.
    2. When visibility falls below 5 miles by day.
    3. In accordance with local orders when approaching the coast.
    4. By a guard detailed by the Escort Commander one hour before an escorting aircraft is due until the aircraft has finally left.

  1. HF/DF Fitted Ships.
    1. The Escort Commander shall order the frequency to be used by ships fitted with HF/DF for passing bearings and shall issue instructions regarding the circumstances in which radio may be used for this purpose.
    2. When any operator hears what he believes to be the start of a submarine transmission, he should be able to warn all other HF/DF ships in company so that they can shift DF receivers to take bearings of the same transmission. For this purpose the codeword SWITCH is available and the procedure will be known as SWITCH procedure.
    3. SWITCH precedes the column number on which the transmission is heard and the number is repeated three times, e.g., the transmission heard on Column Seven, operator broadcasts "SWITCH seven, seven, seven." (RPM 2021)
    4. Bearings will be passed to the Escort Commander using "Q" operating signals. Amplifying information should be passed in plain language or code as ordered by the Escort Commander.



  1. Call Signs.
    1. The following convoy and escort call sign system is effective for Combined Naval use:
      1. W/T and R/T call signs are to be based upon the two-letter or figure-letter convoy radio distinguishing group which is allocated to each convoy before sailing. Suffixes are added to the convoy radio distinguishing group as follows:
Ships or Authorities R/T Suffix W/T Suffix
Commodore CHIEF D1
Vice Commodore LUCK D2
Whole Convoy TEAM D3
Commodore Section --- D4
Vice Commodore's Section --- D5
Senior Officer of Escort BOSS D6
Escort Vessels (Collective) GANG D7
Individual Escort and Support vessel (British) Fleet number preceded by BIT ---
Individual Escort and Support vessel (US) Last digit of hull number preceded by BUG ---
Senior Officer of Support Group FOREMAN D8
Stragglers from Convoy --- D9
Support Group (Collective) MOB D10
Individual Ship in Convoy D plus pennant number D plus pennant number
Escort Carrier No. 1 NEST D1A
Escort Carrier No. 2 COTE D1B
Escort Carrier No. 3 BOX D1C
Escort Carrier No. 4 SACK D1D
Rescue Ships (collective) STRETCHERS D1F
Rescue Ship (individual) STRETCHERS (1, 2, etc.) D plus pennant number
H/F D/F Ships (collective) DUFFER D1G
H/F D/F Ship (individual) DUFFER (1, 2, etc.) D plus pennant number
M/F D/F Ships (collective) METER D1J
M/F D/F Ship (individual) METER (1, 2, etc.) D plus pennant number
MAC Ships (collective) HAWKER D1K
MAC Ships (individual) HAWKER (1, 2, etc.) D plus pennant number
Ships in or near the Van VAN D1L
Ships in or near the Center MID D1M
Ships in or near the Rear REAR D1N
Ship Controlling Aircraft EAGLE D1Q
W/T Guard on Homing Wave --- Convoy Radio Distinguishing Group (in the case of a section of a convoy requiring to use this call sign, the section suffix letter is to be added. See note (d).
Spare --- D1R
Spare --- D1U



    1. Convoy radio distinguishing groups when transmitted by R/T, shall be spoken phonetically. When an R/T suffix has not been provided in the above table, the W/T suffix, spoken phonetically, is to be used.
    2. Individual escort and support vessels shall employ the appropriate W/T call sign or delivery group key numbers from SP 2535 series or SP 2489 series (enciphered in SP 2536 series).
    3. The convoy W/T suffix letter D is invariably assigned to the main body of the convoy. The convoy suffix letters, E, H, I, K, O, Q, S, T, and X are reserved for allocations to sections joining or breaking off from the main body of the convoy. The letter D where appearing in the W/T suffix column of the above table is replaced by the appropriate section suffix letter for convoy section communications by W/T. For convoy section R/T communications, the section suffix letter, spoken phonetically, is inserted between the convoy radio distinguishing group and the R/T suffix.
    4. Special call signs of Rescue, H/F and M/F and D/F ships are only to be used when passing messages connected with the performance of their special duties. At other times, individual convoy call signs are to be used.

[The source document did not contain an entry for Article 5052 - HyperWar Editor.]

  1. The following security precautions shall be observed:
    1. To avoid disclosing the presence or the absence of escort carriers by use or non-use of their call signs, the Senior Officer of the Escort should occasionally employ such calls even when no carriers are in company.
    2. To avoid disclosing the strength of the escort, in the case of British vessels fleet numbers are allocated in an incomplete numerical sequence.

  1. The following call signs are to be used by all aircraft, other than shore based fighters, engaged in convoy operations:
    1. British aircraft are to use the appropriate convoy radio distinguishing group plus a suffix composed of a letter or a letter-numeral combination. For R/T communication, the letters of the convoy radio distinguishing group and the suffix letters are spoken phonetically. The suffix letter indicates the Air Group to which the escorting aircraft are attached (see A. C. I., Article 200). The suffix letter A has been assigned the meaning "all escorting aircraft" and may be used by ships not knowing the Group to which British aircraft belong. Numerals are added to differentiate between individual aircraft of a flight.
    2. U. S. aircraft are to use the appropriate convoy radio distinguishing group plus a suffix composed of a numeral-letter combination (the flight number may be added, if necessary, in order to prevent confusion) as follows:
      Covering Aircraft (collective) VICTOR V
      Commander of Covering Aircraft ZERO VICTOR 0V
      Officer Controlling Flight ZERO ZERO VICTOR 00V
      Plan Number One ONE VICTOR 1V
      Plane Number 2 TWO VICTOR 2V

    4. In order to provide a means of communication in cases where both ships and aircraft are unaware of each other's call signs, the following call signs are to be used:


        R/T W/T
      Ships (or Senior Officer of ships in company) AGUA RN (British)
      AGUA (U.S.)
      Aircraft PISTOL or LINK A7F (British)
      BIRD (U.S.)

      Pistol means "Any aircraft". LINK means "Unknown aircraft I am calling by flashing light". When more than one aircraft is present, the use of LINK indicates which aircraft is being called and by which ship.

    1. Examples: (The convoy radio distinguishing group AB has been assigned. The suffix letter T has been assigned to the Boston Section).
      1. R/T call signs
      2. Commodore ABLE BAKER CHIEF
        Vice Commodore ABLE BAKER LUCK
        Boston Section (collective) ABLE BAKER TARE TEAM
        Senior Officer Support Group ABLE BAKER FOREMAN
        Escort Carrier No. 3 ABLE BAKER BOX
        Covering Aircraft (collective) ABLE BAKER VICTOR (SIX SIX)*
        Plane No. 1 ABLE BAKER ONE VICTOR (SIX SIX)*

      3. W/T call signs
      4. Commodore ABD1
        Vice Commodore ABD2
        Boston Section (collective) ABT3
        Senior Officer Support Group ABD8
        Escort Carrier No. 3 ABD1C
        Covering Aircraft (collective) ABA**
        Plane No. 2 from No. 3 group Halifax (RCAF) ABF2**
        * U. S. aircraft of flight number 66. Flight number may be omitted if no confusion will result.
        ** British aircraft. The suffix letter A is used when the identity of the Air Group to which covering aircraft are attached is unknown. When no numeral is added, the call may be taken to mean "Commander of covering aircraft" if more applicable.


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