Air Fronts: Air Defense FM 44-8; Antiaircraft Operations Room and Antiaircraft Artillery Intelligence Service - Chapter 4. AAOR and AAAIS for Searchlight Defense

Section I. GENERAL

76. GENERAL. For the purpose of this chapter the defense is considered to be composed of one searchlight battalion. It is realized that searchlights will never operate by themselves. This assumption is made only because it simplifies the explanation of the functioning of the AAOR and AAAIS for searchlights.

Section II. ANTIAIRCRAFT OPERATIONS ROOM

77. LOCATION. The AAOR is located in accordance with the principles outlined in paragraphs 12, 13, and 14.

78. EQUIPMENT. a. AA operations board. The operations board is a table approximately 8 by 8 feet and may be broken into sections for ease in transportation. The table is covered by a map or sheet of drafting paper, and protected with some transparent material. The defended area is in the center. Radars, fire units, and OP's are shown. Prominent terrain features and a grid are also shown. The map covers the area outside the defended area to the average pick-up range of the radars. A scale of 1 inch = 1200 yards is suggested.

b. Situation board. See paragraph 17.

c. Status board. See paragraph 18 and figure 2.

d. Platform. A platform or stand about 6 feet long, 4 feet wide, and 30 inches high is required for the AAOO and plot observer.

e. Communications. The communications equipment includes switchboards, radios, and the necessary telephones and head and chest sets.

f. Miscellaneous. Miscellaneous equipment includes chairs AAOR operations journal, display stands, arrows, plotter rakes, and grease pencils.

79. PERSONNEL. a. AA operations officer. The AAOO, as the representative of the antiaircraft defense commander, supervises the operation of the AAOR during his tour of duty. He is responsible for the efficient operation of the AAAIS. He evaluates all information received in the AAOR. He orders changes in the state of readiness. He insures that all units receive prompt warning of any attack. He relays to the units orders and instructions from higher headquarters. In all cases not covered by SOP, he issues orders for the direction and coordination of the entire defense. He restricts or releases illumination and fire as necessary based on information from the AAAIS, higher head-quarters, or the appropriate air forces operations room. He has direct communication with the searchlight platoon command posts and transmits warning information to them. He may delegate this to the searchlight plot observer. He insures that the status board reflects the current operating condition of the materiel. His station is either on the stand or on the floor overlooking the board.

b. Communication officer. The communication officer checks all radio and telephone procedure. He supervises the installation, operation, and maintenance of communications.

c. Plot observer. The plot observer is the senior NCO on duty and is the assistant to the AAOO. He transmits intelligence on incoming targets direct to interested platoon command posts. He supervises the operations of all plotters. When more than one radar is tracking the same target, he selects one to continue to furnish data and orders the other plotters to transmit "Cease giving data" over their data lines. He receives display stands from the raid orderly and places them near the corresponding plots. He records in the AAOR operations journal all actions, changes in state of readiness, and orders received or issued by the AAOR. In large defenses it may be necessary to have more than one plot observer.

d. Raid orderly. The raid orderly is stationed on the floor close to the plot observers. He is responsible for providing the plot observer with correct display equipment. He assigns a number on each new raid.

e. Radio operators. The radio operators are responsible for the proper operation and maintenance of their radios. Each monitors and makes prescribed radio checks with other stations in his net. They enforce strict net discipline. They execute such other duties as directed by the AAOO.

f. Switchboard operator. The switchboard operator is responsible for the installation, operation, and maintenance at the switchboards. He makes periodic checks on and monitors all wire lines in the AAOR. He enforces strict wire discipline. He executes such other duties as directed by the AAOO.

g. Plotters. One plotter is usually provided for each radar "on the air" located in the outer ring. In very large defenses, it may be desirable to designate a limited number of radars to report data. In this event, plotters are provided for only those radars furnishing data. Plotters at the operations board plot the location of targets as reported from the radars. They indicate to the raid orderly the radar making the report, the number of planes, their identification, and their altitude. An additional plotter plots the early warning location of targets on the situation board and notes pertinent information such as number of planes and altitude next to the initial plot.

Section IlI. AAAIS

80. AIR GUARDS. The searchlight radars of the defense are supplemented by reports from the air guards located at each searchlight section. The air guards report over the data line to the AAOR. In the event that data lines are not available the reports are made over the platoon command net and relayed to the AAOR. The sequence of reporting is the same as that used by the OP's. (See par. 44.)

81. SEARCHLIGHT RADARS. The radars on the perimeter of the searchlight area search their normal sectors for targets. (In order to cut down mutual interference and provide for relief and maintenance during the 24-hour day, it will probably be desirable to operate only every second or third radar.) Each searchlight radar will report all targets in grid coordinates. To do this, it is necessary that a grid converter be used. (See par. 82.) This converter may be located in a protected location away from the radar. The grid converter plotter is connected by telephone to the azimuth operator at the radar.

82. GRID CONVERTER. a. A grid converter is constructed for each radar not equipped with a PPI scope. Three selsyns are mounted on the reverse of a plotting board. The selsyns are connected to the data transmission system of the radar to obtain azimuth, slant range, and altitude. Holes´are drilled in the board so that the selsyn spindles may pass through. Light, balanced pointers are mounted on the spindles of the altitude, azimuth, and range selsyns. Calibrated circular scales are marked on the board so that range and altitude may be read. The grid in use in the AAOR is marked on the board so that the actual radar location corresponds to the location of the azimuth selsyn spindle. Concentric range circles are drawn about this point. (See fig. 15.)

 
Figure 15. Grid converter.

b. A plotter reads ranges from the range scale approximately every 5 seconds, notes the location of the target along the azimuth pointer, at the proper range. He transmits the grid coordinates of the target to the AAOR over the data line.

83. UNIT DESIGNATION. For purposes of rapid identification, battalions, batteries, platoons, and sections or fire units are assigned code designations. Battalion or batteries are assigned code words which can easily be understood, such as Cat, Dog, Fox. Platoons within a battery are designated by preceding the battery code word by the platoon number, thus, 1 Cat or 2 Dog. Sections or fire units within the platoon are designated by the platoon code designation followed immediately by the section number, thus, 1 Cat 3, 2 Dog 5. The full code designation should be pronounced in conversation. The abbreviated form such as 1C3 for 1 Cat 3 may be used on maps or overlays. For intraplatoon communication, it is necessary to use only the section or fire unit number.

Section IV. COMMUNICATIONS

84. GENERAL. The normal means of communication in the defense is telephone. There are times when such communication will be impossible, due either to disruption of the lines or to lack of time to establish a complete telephone system. Radio is provided as a standby system for use in such cases.

85. SEARCHLIGHT TELEPHONE NETS. A searchlight area telephone system has three components: the platoon command net, the intelligence net, and the data lines. These three nets are entirely independent, there being no direct telephonic connection between them. These lines may be commercial wires, Army field wires, or a combination of both.

The telephones used by the platoons are usually standard field types.

 
Figure 16. Searchlight platoon command net.

86. PLATOON COMMAND NET. The platoon command net normally connects the six sections of a platoon with each other and with the platoon command post. (See fig. 16.) Normally there are 10 or more telephones on this net—one at each control station, one at each radar, and one at the platoon command post. The phones at the control stations are numbered to agree with the lights in their respective sections, that is, 1 to 6, while the phones at the radar are numbered to agree with the respective radar designations, for example, D1. The phone at the platoon command post is designated CP. Control point lights are normally included in the platoon command net.

87. COMMAND AND INTELLIGENCE NET. The command and intelligence net connects the searchlight plot observer in the AAOR with the platoon command posts. This net is used principally to advise the platoons of the approach of aircraft. Like the platoon command net, it is a "hot loop," with all telephone operators wearing head and chest sets so that ringing is unnecessary. In larger installations it may be necessary to divide the command and intelligence net into several sections, each with its own searchlight plot observer, to obtain satisfactory transmission of data. Normally not more than six platoons should be in one command and intelligence net. The platoon phones on this net take the platoon code designation, such as 2 Fox. (See fig. 17.)

88. DATA LINES. The data lines provide communication between each radar in the outer row of searchlights and the corresponding plotter at the AAA operations board. Over this line, data from the radar are furnished the plotter. (See fig. 18.)

 
Figure 17. Searchlight command and intelligence nets (three-battalion defense).

89. RADIO NETS. Radio nets are established between the AAOR and the battery CP's, and between the battery CP's and the searchlight positions, for command and intelligence purposes. Radio is also used as an alternate method of communication in case of failure of individual data lines. Where

 
Figure 18. Searchlight data lines (two-battalion defense).

no telephone communication exists it is not practical to attempt to furnish data from radars to the AAOR. In such cases, only general intelligence is sent from the radars to the AAOR and no attempt should be made to furnish continuous plots.

Section V. OPERATIONS

90. OPERATIONS. a. When early warning has alerted the defense, the radars not in action start their generators and prepare for operation, except that the transmitter switches are left open. Upon a "pick-up" by a searching radar, the search. light plot observer gives appropriate warning and intelligence to the commanders of alI searchlight platoons. The platoon commander then orders his radars on the air to search. The searchlight radars report all targets in grid coordinates. When one of the oscilloscope operators picks up a target, he announces "Contact." The azimuth scope operator immediately repeats "Contact" to alert the grid converter plotter who in turn calls "Contact" to alert the plotter at the AAOR. When the chief radar operator calls "On target," the azimuth operator reports "On target" to inform the grid converter plotter that accurate data in azimuth and range are available, and also reports any information announced by the oscilloscope operrators concerning number of planes being tracked and IFF indications. The grid converter plotter in turn makes an initial report (see par. 69) to the plotter in the AAOR. Immediately the grid converter plotter starts calling grid coordinate plots to the AAOR approximately every 5 seconds. As soon as altitude data are accurate the grid converter plotter reports altitude of the target. This procedure is repeated until the target has been illuminated, lost, or the searchlight plot observer directs "Cease giving data."

b. When a target, tracked by a radar, is illuminated, the chief controller announces "Target illuminated," and this announcement is transmitted over the platoon command net by the telephone operator. The chief radar operator (CRO) calls "Target illuminated," so that it can be heard by the radar crew, and the azimuth scope operator repeats it to the grid converter plotter who in turn reports it to the AAOR. "Target illuminated" is announced only by the first two lights making the illumination.

c. As soon as any other light forms an intersection on his beam, the chief controllers of the first two lights forming the intersection announce "Intersection." This is repeated in the same manner as in b above, until it arrives at the AAOR. If the chief radar operator then orders "Change target," the grid converter plotter informs the AAOR.

d. If the radar loses the target while a plot is being made the grid converter plotter repeats "Off target" to AAOR.

e. The plotter in the AAOR on hearing the words "Contact" and "On target" stands, to indicate that his radar has detected a target. He plots the course of the target with either colored arrows or grease pencil. He also gives available information of number of planes, altitude, and the radar number to the raid orderly who prepares a display stand. The plot observer crosses his arms above his head to indicate "Intersection" as soon as an intersection is reported.

f. The plot observer, when an initial contact is made and a plot begins, calIs over the command and intelligence net to the platoon concerned to notify them that a target is approaching and gives the grid coordinates.

g. If two radars are tracking the same target the searchlight plot observer instructs one of the plotters to give "Cease giving data" to his radar.