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Chapter Twenty-one
THE CONTROL OF SPOTTING PLANES

A. DEVELOPMENT OF NAVAL GUNNERY.

B. CIC CONTROL.

C. SPOTTING PLANE PROCEDURE:

  1. Position of Spotting Plane.
  2. Radar as Spotting Aid for Surface Gunfire.
  3. Estimation of Surface Distances.
  4. Communications for Surface Spotting.
  5. Frequency Assignments.
  6. CW Abbreviations.
  7. Line of Fire.

D. DUTIES OF AERIAL SPOTTER.

E. RADAR AS SPOTTING AID FOR SHORE BOMBARDMENT.

F. DETERMINING SPOTTING.

G. THE GRID SYSTEM.

H. SPOTTING CHARTS.

I. TARGET DESIGNATION.

J. COMMUNICATIONS FOR GRID SPOTTING.

K. SECONDARY METHODS OF SPOTTING.

L. COMMUNICATIONS FOR LINE OF FIRE SPOTTING.

M. CLOCK CODE.

N. MISCELLANEOUS INFORMATION.

O. NIGHT OBSERVATION.

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Figure 173.

Chapter 21
THE CONTROL OF SPOTTING PLANES

A. DEVELOPMENT OF NAVAL GUNNERY

Naval gunfire has proven its value by its effective destruction of the enemy. New and improved methods of fire control have been devised, enabling our guns to hurl tons of shells over long ranges with deadly accuracy. Modern amphibious warfare has placed greater dt-mands on naval gunnery than ever before. Firing at extremely long ranges, or on island targets, obviously requires an effective method of directing the full impact of a salvo onto the target. Aerial spotting has undergone changes in keeping with the increased demands of ships' batteries. Many methods have been tried, with varying degrees of success, and from these our present standardized spotting procedure has been derived.

B. CIC CONTROL

The aerial spotter is directly responsible to the gunnery officer. To assure the most efficient communications the spotter transmits directly to plot (gunnery). Plot makes all necessary adjustments to correct the ship's fire.

CIC maintains control of the spotting plane whenever possible. This control includes warning the spotter of the approach of bogies, and keeping him informed of the position of friendly planes in the area. All transmissions from the spotter must be received by CIC as well as plot, in order to maintain a complete picture of all activities.

C. SPOTTING PLANE PROCEDURE

Aircraft spotting is divided into two main classifications: Spotting for surface engage-ments and spotting for shore bombardments. Different procedures are used for each and will be covered separately in accordance with current spotting doctrine.

(a) Position of Spotting Plane

Taking into account cloud conditions, AA fire, and air action, the spotter selects an area as close as possible to the target where maximum visibility is offered. The ship may keep a steady fix on the plane, or receive its position by radio. IFF and orbits may be used to identify the spotting plane.

(b) Radar as Spotting Aid for Surface Gunfire

Spotting has been greatly aided by the introduction of radar as a very accurate method of spotting. Radar, however, can only be used when the target is within the line of sight of the firing ship.

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An accurate range and bearing can be taken by radar from the splash (geyser of water thrown in the air when a shell lands); and in case of a full salvo, the deflection and range of the MPI (mean point of impact) may easily be obtained from the radar scope. Normally, in a full salvo, the shells land in a ladder-like pattern covering an area of approximately 50 yards in width and up to 500 yards in length, depending on the caliber of the guns and the range being fired.

Radar, observers aboard ship, rangefinders, and directors are all utilized in spotting, as well as the aerial spotter. Sometimes radar will be used to spot deflection, and the aerial observer to spot range only. However, deflection spot by the aerial spotter is usually considered preferable to radar deflection spot.

The aerial spotters usually spot both range and deflection in yards since use of MIL scale would require aerial spotter to know range from firing ship to target.

(c) Estimation of Surface Distances

Estimating distance on the surface is extremely difficult under any conditions. The aerial spotter is helped a great deal in range estimation by knowing the pattern length of a salvo and using it for a yardstick in spotting. Estimates of deflection spots require a great deal of experience in order to obtain any degree of accuracy. Pilots most commonly use target size as guide in spotting range and deflection. Example, DD is 100 to 125 yards long, OBB 200 yards long, etc.

Estimations of range from firing ship to target are best learned from experience. Distance charts of altitude to horizon are of some value in aiding the aerial spotter, but are too dependent on visibility to be relied on solely.

(d) Communications for Surface Spotting

Aerial spotting may be successfully accomplished by either voice or key transmissions,-and blinker can sometimes be used when all else has failed. In order to meet the high speed requirements of modern warfare, direct voice communication between the aerial spotter and the ships fire control officer is desirable. VHF/UHF is used whenever possible. In task

force operations the situations are too variable to establish a standard doctrine. Locale and distance to the target, weather conditions, and enemy opposition must be considered in determining the method of communicating. The OTC will determine whether voice or CW will be used, having due regard for the tactical situation, the requirements of security, and the prevalence of interference.

(e) Frequency Assignments

Normally each battleship and cruiser will be assigned a different spotting frequency to be controlled solely by that ship. When a destroyer wishes an aerial observer, the assignment of a spotter is made by OTC. The destroyer must use the frequency of the assigned plane. The plane may be required to spot for the destroyer and its own ship simultaneously.

(f) CW Abbrevations

Standard abbreviations are used on CW communications in aircraft gunnery observation, and are shown in CSP 2156 series.

(g) Line of Fire

The line of fire is the primary factor in controlling surface spotting. The aerial spotter must keep the position of the firing ship clearly in mind relative to the target ship or any spots sent will be of no value whatsoever.

D. DUTIES OF AERIAL SPOTTER

It is the responsibility of the aerial spotter to keep the OTC and CIC, in addition to Plot, informed at all times of the following:

1. Course and speed changes of enemy force.

2. Formations or disposition of the enemy force.

3. Damage inflicted to enemy force.

4. Activity on CV decks, if carriers are involved.

For more detailed information concerning surface spotting, refer to USF-75.

E. RADAR AS SPOTTING AID FOR SHORE BOMBARDMENT

There are various tactical situations in which an aerial observer will be required to

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spot for naval units engaged in a shore bombardment. Amphibious warfare requires a highly accurate method of spotting since shelling may be carried on against targets as close as 100 yards to our own troops. An area bombardment, such as in a raid to destroy or neutralize enemy bases, does not require as high a degree of accuracy from the spotter, but every effort must be made to make every salvo count.


Figure 174.

Many factors must be taken into consideration to determine what method of spotting can be used effectively in shore bombardment. The target will not be visible to shipboard observers or within the line of sight of radar unless it is situated on the shore line or beach area. Aerial observation and shore fire control parties are relied on to a great extent both for spotting the fall of shot and selecting targets of opportunity.

The use of special fighter unit spotters is frequently resorted to during amphibious operations when AA or enemy air opposition is too heavy for the regular aerial spotters. On such occasions the ships fire when the fighter calls for "salvo," at which time the plane commences the dive, timing his dive so as to be in the best position to spot at the expiration of the time of flight given by the bombarding ship.

F. DETERMINING SPOTTING PROCEDURE

Familiarity with the area under attack together with weather conditions, range to the target, terrain, and enemy opposition will all determine the spotting procedure to be used. The aerial spotter in all probability will not

be able to keep the firing ship and the target area in view at the same time. The spotter will be required to correct for both range and deflection. Landmarks, such as roads, pinpointed targets, hills, and rivers, will aid greatly in locating target areas and spotting the salvo correctly. Having no visible contact with both the firing ship and target area, the spotter cannot depend on the line of fire as a reference in his spotting. Many procedures have been attempted to eliminate using the line-of-fire as a reference. Only the most widely used and standardized procedure will be discussed here. Other systems are variations which are used as the situation demands.

G. THE GRID SYSTEM

The most widely used method of spotting a shore bombardment is the grid system. Targets may be quickly and easily located by reference to the grid square. Fire may shift from one target to another by reference to the grid. New targets of opportunity, or targets previously not located, may be pinpointed accurately. Each department concerned may thus keep a running plot of the entire engagement. An over-all picture of the situation is available at all times to the entire chain of command.

H. SPOTTING CHARTS

Grid maps may be constructed from charts, overlays on maps, or by superimposing the grid on photographs. The grid map used by the aerial observers must be pictorial--showing roads, buildings, cleared areas, hills, and other landmarks visible from the air. Color should be used wherever possible, showing water in blue, reefs in white, and wooded areas in green. Contour lines should be shown every 20 feet, with hachure marks for peaks and cliffs. Maps should be as large as can be conveniently used.

I. TARGET DESIGNATION

Targets definitely located should be marked as to type and circled with red ink. They need not be numbered as fire will be called on for target areas by grid location. The spotter will call the area where the salvo lands and the

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ship will adjust fire to shoot into the desired target area.

J. COMMUNICATIONS FOR GRID SPOTTING

Frequencies for spotting will be as assigned in the communication plan. VHF will be used if possible. All spotting and communications will be in plain language, using voice transmission only.

K. SECONDARY METHODS OF SPOTTING

There are times when the aerial spotter will be able to keep visual contact with the firing ship and still maintain an unobstructed view of the target. If maps or grids are not available, the easiest method of spotting is to use the line-of-fire from ship to target for spotting deflection and range. As long as the line of fire is known the spotter may estimate the correction to apply to place the salvo on the target. An experienced spotter may not need visible contact with both ship and target as familiarity with the salvo pattern will show the direction fired from. This system is impracticable, however, when single-round salvos are being fired.

L. COMMUNICATIONS FOR LINE OF FIRE SPOTTING

Voice communication, using plain language, is mandatory. Spotting may be done, as in surface gunfire, by giving the necessary correction to place the salvo on the target. No abbreviations are used in voice spotting. To raise a salvo 100 yards the spotter will say "Up 100. Up 100, This is Ace Turfclub." Deflection is also spotted in the actual yardage desired. Range is spotted first and then deflection. This is repeated and followed by the spotters call. The aerial observer may report targets of opportunity and request the ship to shift fire by telling in a clear and concise report exactly what is seen. A reference point must be used and a prominent landmark is usually selected.

M. CLOCK CODE

There is one other system of spotting indirect fire although it is not widely used. Maps of the area are needed and targets or landmarks must be marked. The spotter calls the actual spot where the salvo lands by using a clock code. True north is 12 o'clock and the target being fired on is the center of the clock. Thus a salvo landing 300 yards west of the target would be called by the spotter as "9 o'clock 300 yards." The ship will apply the correct adjustment to fire on the target. To shift fire, or report targets of opportunity, the spotter uses the same procedure of clocking, giving a known landmark or target as the reference point.

N. MISCELLANEOUS INFORMATION

In view of the many situations which may arise, the spotting plane must remain in a given area as much as possible to aid CIC in keeping the plane's position plotted. Normally the spotting plane will be a seaplane (VO-VCS type aircraft) and it should be remembered that as such there may be presented the opportunity of utilizing such aircraft for search and rescue. The spotting plane is near to the target area and valuable time may be saved in using the spotting plane during a lull in the firing thus saving the launching of other aircraft or fleet units.

In order for a ship to maintain accurate fire, plot must keep a running fix on the ship's track. Radar has proved invaluable in maintaining accurate position reports of the ship on its firing run. Whenever radar spots can be utilized, whether with or without aerial spotting the average spots given will be used in order to give the best possible service to the parent ship.

During both surface engagements and shore bombardments each battleship and cruiser normally launches its own spotting planes.

Secondary frequencies will be assigned for use in case of jamming or interference by the enemy on the primary spotting frequencies.

O. NIGHT OBSERVATION

Spotting may be conducted during night bombardments if conditions permit Normally the launching and recovering of VO type aircraft is too hazardous after dark, but in many instances successful aerial spotting has been carried out from patrol planes using star shells and flares for target illumination.

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Transcribed and formatted by Larry Jewell & Patrick Clancey, HyperWar Foundation