War Instructions United States Navy 1944

Chapter 5. General Instructions for Communications,
Contact Reports, Recognition and Identification,
Radar, Aviation Personnel Rescue

Section I. Communications

500. Under the Commander in Chief, U.S. Fleet, the commanders in chief and commanders of fleets are responsible for controlling and coordinating naval communications for stations and operating forces under their cognizance. They take necessary measures to insure the strict observance of the prescribed instructions regarding communications, including security and intelligence, and issue such additional instructions as may be required.

501. Radio communications is kept to the minimum consistent with the needs of the situation. Radio silence is imposed when required. If necessary to use radio, the judicious selection of a frequency to avoid interception and the lowest power consistent with getting the message through are used. Contact reports are made with ample power to insure reception. Use of voice circuits necessitates strict circuit discipline in order to preclude self-jamming of those communication channels with unessential transmissions during stress of action.

502. When radio silence is imposed, the forces or units of the command are so disposed, to the extent practicable, that communications can be maintained throughout the command without the use of radio. Visual methods of signalling or other auxiliary methods are always used in lieu of radio when possible and practicable. Breaking of a set condition of radio silence by the officer in tactical command or by an individual unit for an emergency transmission is not interpreted to mean that radio silence is automatically removed for all units of the force. Prescribing a change in the effective condition of radio silence is a function of the officer in tactical command.

503. Commanders and commanding officers of detached ships are alert to recognize the condition when radio silence may be broken and a continuous flow of information may be given to higher echelon commanders and other units. Such occasions usually arise when action is imminent or if our force is positively known to the enemy. Likewise, commanders concerned are alert to reestablish radio silence when all necessary information has been transmitted, or when no longer in contact with the enemy forces and there is a chance for again concealing our position. Once radio silence is broken, the officer controlling the circuit insures that strict radio discipline is maintained, and unnecessary transmissions are eliminated. Particular care is necessary with regard to voice circuits, not only to eliminate unnecessary transmission, but also to insure that classified information is not transmitted in plain language. Warning of the enemy's approach must be positive to all ships in the area. When a single voice circuit is relied upon to furnish this warning, a secondary circuit is provided, when equipment permits.

504. Communication personnel are kept informed of the existing organization in order that they may act intelligently.

Section II. Contact Reports

505. Contact reports are reports of the enemy made by ships or aircraft which are in visual, sonar, or radar contact with him. The first report, giving the information immediately available when the contact is first made, is known as an initial contact report. Subsequent reports containing additional information are referred to as amplifying reports. An amplifying report, for identity and clarity, refers to the initial report which is being amplified.


506. In general, the following are of primary importance in a contact report:

  1. The presence of an enemy force.

  2. The location of the force.

  3. The composition of the force.

  4. The direction of movement of the force. If the enemy is zigzagging this fact is reported, as well as the base course.

In addition to the above, other items that are important, and either included in the initial report or sent as amplifying report as soon as available, are:

  1. The speed of the force.

  2. The disposition of the force. Enemy disposition, particularly of a large force, is important when action is imminent. The presence of battle cruisers, aircraft carriers, and light forces, and their disposition relative to the enemy battle line is important, as are the order of battleship divisions and the battleship formation. Sometimes positive knowledge of the mere presence of an enemy force in a certain area is of vital importance to the officer in tactical command. At other times, when the presence is known, the exact location, composition, and actions of the force are of the greatest importance. The reporting ship or aircraft attempts to provide all the above information, but does not fail to make a report merely because all the information is not available. An initial report is not delayed to obtain this information.

  3. State of the weather and significant changes therein, especially as affecting flying conditions.

The following items are of such importance that they are tantamount to initial contacts and are reported immediately upon occurrence:

  1. Reversal of course or radical course changes by enemy ships.

  2. Destruction of large enemy units.

  3. Launching or recovery of planes by enemy carriers.

  4. Sighting of enemy aircraft formations.

  5. Separation or junction of enemy forces.

  6. Presence of enemy submarines or mine fields in the path of our force.

507. Contact reports are divided into two categories as regards urgency of delivery to the officer in tactical command:

  1. Reports which are probably of sufficient importance to cause a change in the plans of the officer in tactical command, or to cause him to take counteraction. Such reports have highest priority.

  2. Reports which are considered to be of less urgency. These are sent with a lower degree of priority, in order to avoid delaying urgent reports of other commanders.

The division of reports into these categories cannot be definitely prescribed and is left to the discretion of the originator.

508. Positions used in contact reports are always the position of the enemy force. The time of origin of the report is always the time when the enemy's position, composition, disposition, course, or speed is as reported.

509. Enemy positions may be reported in latitude and longitude, by bearing and distance from the main body, fleet guide, a prominent land mark, a designated geographical reference point, or by use of a grid. When the enemy is distant, positions are given in latitude and longitude, by bearing and distance from a designated geographical point, or by a grid. Otherwise, the position


of our forces might be indicated to the enemy. However, when the enemy is in the close vicinity of the officer in tactical command and sight contact with our own forces is probable, or when it is apparent that the position of our own major force is already known to the enemy, positions are given in terms of bearing and distance from the officer in tactical command, thus facilitating plotting by that officer and other commanders concerned.

510. In reporting the composition of forces, names or terms descriptive of mission or assumed enemy intention, such as "main body," "striking force," "attack group," "scouting fleet," etc., are carefully avoided. Assumptions as to the mission or intentions of enemy force are made only by the officer in tactical command. Normally the numbers and type of vessels and aircraft sighted are reported. When a force of indeterminate composition is sighted, expressions such as "large force," "large number of destroyers," etc., may be used to advantage, and more detailed information given in amplifying reports. If individual ships can be identified by name, they are mentioned.

511. The following general instructions are set forth for guidance in making contact reports:

  1. While duplication of reports is avoided, it is preferable that the officer in tactical command receive two identical reports of the same force than to remain in complete ignorance of its presence. A vessel can generally intercept reports made by other vessels in her vicinity or attached to the same task group, and, by refraining from duplicating the reports, prevent the congestion of communication channels.

  2. When a report is made, only facts are stated. Opinions or conjectures as to enemy intentions are not desired, unless the commanding officer of the reporting vessel feels that he is in a better position to make them than the officer in tactical command. If opinions or conjectures are expressed, the language of the report indicates how much is fact and how much is opinion. Vessels and aircraft are reported as enemy only when they have been definitely identified as such. If there is only a presumption that they are enemy they are reported as unidentified.

  3. When doubtful as to the accuracy of the information reported, such doubt it clearly stated, or the information not considered accurate is omitted.

  4. In reporting the presence of enemy forces, if the information is obtained by other means than actual sighting, such means is indicated, unless it is obvious to the recipients of the report.

512. All initial contact and amplifying reports from ships and aircraft in contact with the enemy are addressed to the officer in tactical command, who has the widest sources of information, and therefore, usually is in the best position to evaluate all reports received. Responsible commanders promptly relay all contact reports to the officer in tactical command, unless they hear him receipt for them, even though it is quite probable that the officer in tactical command may have already intercepted the report on a frequency he is believed to be guarding.

513. Evaluation of despatch information and summaries of important information received from returning aircraft also are transmitted to the officer in tactical command by the officers controlling flights, but the work of such evaluation and such summaries must not be allowed to delay the immediate relaying of original reports.

514. It is important that no time be lost in the transmission of contact reports after contact has been made. To this end each commanding officer insures that the sources of information and the communication organization are so integrated as to have continuously available basic information, which includes own position, weather, to whom contact reports are transmitted, and the circuit to be employed.

515. Each commander through whom enemy information reports are transmitted evaluates the information for his own use, without delaying the forwarding of the report to the officer in tactical command.


Section III. Recognition and Identification

516. A most important factor in war is positive recognition and identification of friend or enemy. Through lack of thorough training, absence of coordination, and due to misunderstanding, friends lose their lives or the enemy is permitted to escape. It is essential that personnel receive proper indoctrination on this subject.

517. The following definitions of the terms "Recognition" and "Identification" apply: Recognition is the process of determining friendly or enemy character of others. Identification is the process of indicating your friendly character.

518. The basic means of recognizing ships and aircraft is by familiarity with silhouettes and markings. Secondary means of recognition and identification of friendly units contacted is by prescribed use of various electronic and visual systems. Emergency means of identification to give immediate identification of friendly characteristics also employ electronic and visual systems.

519. Definite knowledge of the location and expected course of action of all friendly units, including aircraft, in the area of operations is an essential contributory factor to the above enumerated means. When a friend approaches whose movements are unknown to the personnel charged with recognition and identification, command has failed in an important function. Therefore, it is requisite that responsible commanders disseminate within and without their commands adequate information of expected movements and the locations of friendly units who may possibly contact each other. However, meeting a friendly ship at an expected time and place is no assurance that an enemy ship is not also in the vicinity. This is particularly true of submarines. Relying too implicitly on advance information is unsound and not an acceptable substitute for effective recognition.

520. A contributory aid to recognition is maintenance of a continuous plot of ships in company and own planes utilizing both radar and visual observations. Particular attention is paid to displacement of own ships and planes from assigned stations.

521. In order to become proficient in basic means of recognition, appropriate publications and instructions are made available. Training in the recognition of silhouettes and marking of friendly and enemy ships is effectively conducted to the end that all officers, quartermaster, signalmen, and others who are detailed as lookouts become thoroughly familiarized therewith.

522. "Identification of Friend or Foe" is an electronic system installed in ships, aircraft and shore facilities to recognize friendly contacts made by radar. It is all-important that the commander know the fundamental operating principles and limitations of the particular IFF system in current use. All IFF systems consist of the following units:

  1. Interrogator responsor--a unit which when actuated sends out a challenging signal of the proper characteristic and receives the reply from the transpondor challenged.

  2. Transpondor--a unit which receives a challenge and automatically transmits a reply of a definite characteristic.

It is incumbent on responsible commanders to see that their commands are informed of IFF systems and codes to be used if there is any deviation from the current doctrine.

523. Visual methods of identification consist essentially of:

  1. Sending by visual signalling apparatus a designated letter or numeral or a sequence of letters and numerals.

  2. Displaying of prescribed flag hoists, particularly when entering or leaving ports.

  3. Displaying a designated array of lights, which are arranged in a vertical line or other prescribed manner.

  4. Using pyrotechnics.

  5. Using designated colored strips or markings arranged in prescribed manner.


524. In general vertical or other arranged identification lights or certain pyrotechnics are for emergency purposes and are used as follows:

  1. To establish identity of ships or aircraft when fired upon or when attacked or menaced by friendly ships or aircraft.

  2. In night battle melee when it becomes necessary to indicate own identity or to establish identity of ships in vicinity.

  3. During periods of low visibility or darkness when unexpected contact is made with a ship or aircraft whose identity is not at once apparent.

  4. By submarines to indicate their identity before surfacing in the presence of friendly ships or aircraft.

  5. Between ships or aircraft to establish their identity when other means are impracticable or not available.

525. When on the surface submarines employ appropriate means to establish their identity and, when submerged, in addition to the use of pyrotechnics, they also identify themselves by sonar means, making prescribed transmissions over their supersonic apparatus. When prescribed, surface vessels employ supersonic apparatus for purposes of recognition and identification to submarines.

526. Emergency identification signals are displayed only long enough to indicate friendly character and if practicable are verified by the prescribed standard recognition identification signals.

527. Since visual identification signals will indicate enemy character to an enemy as well as friendly character to a friend they are not initiated until prepared to take immediate offensive action.

Section IV. Combat Information Center

528. Maximum combat efficiency by individual ships and task organizations can best be attained through full utilization of all available sources of combat intelligence. To develop this concept, the establishment in a ship of a center, in which information from all available sources can be received, assimilated, and evaluated with a minimum of delay, is essential. Through the evaluation of all available information by trained personnel, such data can be quickly disseminated to the flag and commanding officers, to other control stations concerned over interior communication circuits, and to other ships and aircraft via external communication facilities. The means for accomplishing the foregoing and assisting the commander in planning and executing a correct course of action, is provided by the combat information center.

Section V. Radar

529. Radar in essence is beamed VHF (very high frequency) or UHF (ultra high frequency) pulsed radio transmissions. These transmissions upon striking an object reflect some of their energy back to the source. By an accurate timing device the range of the object is determined. Bearing is ascertained by centering the beam of the radar on the object or by measuring the center of the echo. In general the bearing accuracy is determined by beam width and type of presentation; range accuracy by the accuracy of the timing circuit.

530. Radar transmission being an electro-magnetic wave similar to radio transmission is subject to interception from outside source at varying distances depending upon the frequency (wave length), power, and atmospheric conditions. Usually radar transmission is line of sight but at lower frequencies some bending occurs. If the proper receiver is available and the frequency of transmission is known the use of radar may be detected. The range of detection is greater for the lower frequencies of emission. Normally the presence and direction but not the position of the radar emission is disclosed.


531. Radar equipment is installed in ships, aircraft, and shore stations to perform the following:

  1. Warn of presence of aircraft or surface units.

  2. Assist in solving fire control problem.

  3. Detect enemy radar and effect countermeasures.

  4. Identification of Friend or Foe (IFF).

532. It is incumbent upon the commander to know the capabilities and limitations of the various radars available in the command in order that they be employed to the maximum effectiveness.

533. The control and use of radar in a tactical organization is a function of the officer in tactical command.

Section VI. Air Sea Rescue Provisions for Aviation Personnel

534. In order to conserve the numerical strength of our trained aviators and aircrewmen and to maintain the morale of aviation personnel, the commander sees that detailed rescue provisions are considered in the planning for particular air operations, and that the necessary specific information is promulgated to lower echelons and others concerned.

535. If large scale air attacks by aircraft from units afloat are contemplated on distant objectives, rescue facilities are provided near the scene of action if possible and feasible. Rescue vessels are stationed at definite reference points just prior to the commencement of an air strike on the objective and are subsequently maneuvered as necessary to effect rescues of downed airmen.

536. The nature of opposition to be expected influences types of rescue facilities employed. The following are used in accordance with their suitability:

  1. Submarines.--Used particularly when aircraft attack objectives some distance from the air (carrier) task group. In warfare where our own surface units and enemy submarines may be encountered at the same time, the use of submarines for such rescue tasks is dangerous.

  2. Aircraft.--Seaplanes are used as practicable to rescue survivors, particularly at distances away from land or surface forces.

  3. Surface vessels other than submarines.--Light forces are used to accomplish rescue, but are not usually stationed at reference points. They proceed to the location of the personnel in the water when feasible and so directed.

  4. Specially equipped and designed rescue boats.--These are usually land-based or may be carried by large surface vessels and operated as necessary.

537. Each aircraft is provided lifesaving equipment with the necessary detailed items to assist in rescue operations.

538. Rescued aviation personnel are reported to and, when not wounded, are returned to their own ship as expeditiously as possible.

539. For air strikes made without advance planning, for example, strikes made on distant enemy surface units which have just been contacted, prior arrangements for rescue in the area where the strike is to take place are not always possible. Rescue operations are, however, initiated as early as practicable thereafter.

540. The commander usually designates in advance an agency, normally a carrier, to correlate reports of downed aircraft and to control rescue operations using available rescue facilities.

541. Air coverage is provided, if practicable, to rescue vessels or rescue aircraft, and serves to:

  1. Protect rescuing unit from enemy attack.

  2. Assist in recognition of rescuing unit to other friendly aircraft.

  3. Assist in locating survivors, and guiding the rescuing unit.


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