Air University Review, January-February 1968

Computer-Generated Map Data
An Aid to Command and Control

Major John A. Wohlman

With the issuance of the initial order by a caveman to a receptive individual who thus became subordinate, the concept of command and control was born. As people began to congregate for mutual aid and protection, the necessity for a hierarchy of authority became apparent. Though survival of the fittest was often the criterion for selection of a leader, the tribal chief, once recognized, was responsible for decisions until he was challenged and over-thrown by an ambitious follower.

The inception of a quasi-military organization magnified the requirement for command and control. In early times, a chief or commander encountered relatively simple problems, though they were nonetheless significant to him. He predicated his judgment on a strategy the sum total of which he carried in his head or pocket. His area of immediate concern was often entirely within eyesight. With a properly positioned peripheral guard, he had sufficient warning of an enemy threat to give him adequate time to prepare a defense or counteroffensive for employing his forces. However, as methods of transportation and communication improved and weapons became more sophisticated, the potential battlefield grew proportionately. Commanders soon realized that they needed a staff to provide information upon which to base decisions.

From the earliest recorded history, military leaders have exercised command and control. Yet in today's space age this term has suddenly acquired a mystical connotation. In his Maxims, Napoleon wrote, "Commanders-in-chief are guided by their own experience and genius."l This axiom is as valid today as in the era of Alexander the Great. However, the advent of electronic devices has seemingly introduced the notion that command and control is now suddenly emitted from a magical black box. In reality, the employment of mechanical devices to aid in computation has been traced back thousands of years. Whether gleaned from advance scouts of yesteryear or extracted from the puzzling innards of today's computer, the information obtained is merely the essential data upon which a commander determines a course of action-a means to an end. Thus, command and control may be defined as an interaction of man and machine to provide for the collection, processing, storing, and retrieval of information and its application by a commander in making timely decisions.

The compression of time and space stemming from the continual improvements in aerospace technology and the sophistication of weaponry has simultaneously reduced available reaction time. In an age of supersonic aircraft, intercontinental ballistic missiles coupled with nuclear warheads, and warning times diminishing to a matter of minutes, today's commander must have immediately available and in usable form the pertinent information upon which to base his decisions. The volume of raw data supporting these decisions has become of such magnitude that it is often humanly impossible for an individual to manipulate it in the allotted time. Gone are the days when a commander could recall from memory the particulars concerning available forces which might be applied to a specific operation. In-commission rates, weather, and numerous other factors change daily or even hourly. To keep abreast of these criteria manually has become an insurmountable task. The large-scale, high-speed digital computer with its associated equipment has alleviated this problem to a degree, but future developments in the field of cybernetics must keep pace with advances in the other sciences lest we encounter a time gap.

SAC Automated Command Control System

Within the Strategic Air Command, the potential of automated data processing as an effective aid for control of the force was recognized as early as 1954. A closed-circuit color television network was first utilized as an interim display facility. After a computer was put to use in 1957, the main functions were resolution of time-over-target conflicts, monitoring the status of the force, flight- following Emergency War Order (EWO) missions, and peacetime exercises. The need for even more rapid transmission, processing, and automated presentation of information ultimately led to the development of the SAC Automated Command Control System (SACCS).

The key to the success of SACCS is communication, speed, and flexibility. With warning time of an impending nuclear attack having been reduced to a matter of minutes, SACCS was designed as a real-time system. A real-time computer system has been defined as one that controls an environment by receiving data, processing them, and returning the results quickly enough to affect the functioning of the environment at that time.2

The SACCS was delivered to Strategic Air Command by the contractor in March 1965. Programming problems generated largely by an inability to keep pace with the dynamic SAC environment resulted in the system's not being functionally usable. Continued debugging by SAC and contractor programming personnel led to a limited usable product by July 1965.

The SAC Automated Command Control System performs in seven significant areas of operationally interdependent functions: planning, force readiness, force exercise, alert and execution, force control, command data exchange, and continuity of command. 3 The SACCS is composed of three subsystems:

(1) Data Transmission Subsystem, which provides the communication network between the bases, the Data Processing Subsystem, and the Data Display Subsystem;

(2) Data Processing Subsystem, which is composed of three large digital computers known as Data Processing Central (DPC);

(3) Data Display Subsystem, which embodies four data display centrals to provide multicolored screen projections and black-and-white printer displays.

In actual operation, the Data Processing Central is initially primed with information on current force structure, requirements, facilities and base status, and other pertinent information, which constitute a data base. In the event the computer is destined for planning purposes, the data base includes climatological and weather data, aircraft performance characteristics, intelligence information, force posture, etc. An integral part of the initiation of the system is the loading of groups of instructions, called programs, which dictate how the raw data received should be processed.

Communications equipment known as Remote Communication Central (RCC) directly connects SAC bases throughout the world to the Data Processing Subsystem via a complex network. Each site is capable of inputting precisely formatted messages on a variety of subjects; e.g., alarms, weather, force generation and execution, materiel status, and flight plans. Message traffic is routed through an Electronic Data Transmission Communications Central (EDTCC), one of which is located at Hq SAC and at each SAC numbered air force. The EDTCC, itself a large computer primarily designed as a traffic routing and switching device, analyzes the input, determines the destination from header information, and dispatches it to the DPC for further processing.

At the DPC the input is ingested and compared/evaluated with the previously established data base. Inputs of a routine nature result in a mere update of the data files. However, if manipulation of the data reveals a condition that warrants immediate Headquarters consideration, a display is forced. Displays may also be requested, when desired, by using one of numerous display request devices.

Displays are either output on impact printers, which print in a typewriter mode at the rate of 800 lines per minute, or are optically projected on screens in one or more of the SAC command posts. Printers are strategically located throughout the command, a minimum of one being associated with each request device. Projection screens for wall displays are installed in each of SAC's numbered air force headquarters. Each command post screening room consists of from four to six 16' by 16' projection screens capable of accommodating a display of similar size or from one to four 8' by 8' displays simultaneously on each screen.

computer-generated map data

Computers are being utilized in ever increasing numbers to produce map data as an aid to command and control. At Headquarters North American Air Defense Command (NORAD), giant screens stand ready to accommodate a variety of map displays. In the event of an apparent attack on the U.S., a computer-generated map will show the probable launching sites of incoming missiles. Nearby, a projection of North America will reflect computer-predicted impact points. (A similar bomb and missile alarm map is located in the office of the President of the United States and at SAC headquarters in Omaha, Nebraska.) Other display boards at NORAD's Combat Operations Center under Cheyenne Mountain portray significant aircraft activity. Identified but not processed for display are the thousands of military, commercial, and private flights that traverse the country daily. All unidentified flights are monitored continuously, however, until positive identification or interception has taken place. Flights of special interest are also monitored on the huge maps.

The raw data utilized by the computer in generating these displays originate from a multitude of radar sources, such as BMEWS, Dew Line, etc. Within minutes, the various inputs are transformed into meaningful data, which are then properly positioned and displayed.

The familiar theory that one picture is worth a thousand words was applied in the designing of the SAC Control System. Though the majority of displays may be achieved in tabular form, it was desired that SACCS also provide certain information in pictorial fashion on map backgrounds. Evolvement of map displays was realized in early 1967, and a flight profile capability should ultimately be achieved. Further exploration of the map medium is under way, with intelligence displays and expanded flight-following capabilities on the horizon.

Let us suppose that from anyone of a variety of causes謡eather, runway repair, suspected sabotage容ight air bases within the continental United States are unavailable for operations at a given time. Certainly a commander is cognizant of the exact location of his installations, and a tabular display listing the unusable bases by name could provide the essential information. However, a map display of the U.S. reflecting a legend-defined red symbol at the geographical location of each unavailable base would better provide the same information. Immediate attention would be drawn to a pattern that conceivably might be developing or the fact that an excessive number of bases in one sector of the country were nonoperational.

Or consider a tabular listing of flight plan route points for a particular aircraft sortie compared with a map display of the same flight plan. Comprehension of the intended flight path is immediate when the flight plan is viewed on the map display.

Weather information also readily lends itself to map presentation. Of particular value are displays of severe weather areas outlined in colored symbols. For example, hurricanes and typhoons appear as red circles and are identified by their code name. Tornadoes are displayed as red polygons and thunderstorms as yellow polygons, each marked by its storm identification.

Obviously, certain information, such as numbers of alert aircraft available or vehicles deadlined, is not suitable for map presentation. Consequently the map capability within SACCS thus far has been limited to display of data relative to alarm, weather, operations, and materiel and various combinations thereof.

Map display

A map display consists of a static map background over which is superimposed various dynamic information. This is accomplished by means of two types of optical projectors. The first is known as a projector, still picture (PSP), for projecting the background map, and the second is a Group Display Generator (GDG) for display of the dynamic overlay information. The PSP is not unlike an ordinary slide projector and may operate either independently or in association with a GDG. To display the dynamic information, the Group Display Generator receives from the Data Processing Central digital data which it converts to alphanumeric characters and symbols, which are positioned on a charactron tube. The character image is transferred to a negative film, from which a film positive is made and positioned for optional projection in the GDG. The entire operation requires approximately 15 seconds.

A GDG is subdivided into four positive film stations, each of which projects a display onto an 8' by 8' quadrant of the screen. Symbols are projected or lines traced by means of sequential positioning of a given symbol. The GDG is also capable of generating display data in any of seven colors, thus permitting placement of color coding emphasis on significant items. Red appearing in a display indicates an emergency or alert conditions, while green means a satisfactory situation or completed action. Other colors are representative of marginal conditions, exercise data, war gaming, etc.

modes of projection

Screen projection of a tabular display is accomplished in typewriter mode with the normal 8' by 8' screen quadrant accommodating 48 lines of information, each line with a maximum length of 72 characters. Individual character positions are broken down into 70 small squares, 7 units wide and 10 high. In this mode, actual character styling occupies only 5 of the 7 horizontal and 7 of the 10 vertical spaces, the remainder providing for automatic character and line spacing.

For map presentation, the placement of dynamic display data is by position mode. Each of the 70 squares constituting one character position in typewriter mode is singularly addressible in the position mode. Thus the 48 vertical lines expand to 480 positions (10 X 48), and the 72 horizontal lines expand to 504 positions (7 X 72). Placement of a character for a map display is determined by computing the x,y coordinates, x being one of the 504 possible positions along the horizontal axis and y one of the 480 locations along the vertical axis.

The current SACCS map library contains at least one slide of each geographical area of interest or concern throughout the world. With three types of maps用olar stereographic, Lambert conformal, and Mercator葉he slide inventory normally consists of multiple coverage of known or potential trouble areas. Considerable research went into the development of the basic paper charts from which the map slides were ultimately generated. Ideally, areas of water would be blue in color, land masses brown, and Communist-dominated areas red. A problem arose, however, in maintaining color consistency in dynamic overlay data when the data extended over more than one background hue. For example, a red line changed in tone as it passed from a brown land mass through a red Communist area and over a blue-shaded ocean.

To permit conversion of input latitudinal and longitudinal reference points to the x,y coordinates for subsequent projection on a map background, certain information pertinent to each map slide must be available. Therefore, stored in the computer data files and referred to as "parametric data" is the following common information for each slide:

Type of projection

Legend position indicator

Map boundaries葉he two extreme latitudes and longitudes that encompass the map area

Corner point様atitude and longitude of the extreme upper left corner of the background map, expressed in radians

Rotation angle葉he angle of rotation required to position the displayed information correctly, expressed in radians

Distance葉he distance, in inches, between 2 points on the same longitude

Distance reference points葉he latitude and longitude of the 2 points used in determining the distance.

For the Lambert conformal projection, additional information must be provided:

Reference longitude要alue of any longitude contained on the map

Standard parallels used in the source map from which the slide was made. 

And for the polar stereographic:

Angle from the "new x axis" (horizontal edge) of the slide to the Greenwich meridian, measured counterclockwise.

With these reference data and utilizing formulas provided in part by the Aeronautical Chart and Information Center, St. Louis, Missouri, the map's computational program transforms the latitude and longitude of the dynamic map data to x,y coordinates and rotates these computed coordinates for proper positioning on the selected map background.

slide selection

In calling for a map display, the requester may specify a particular map background, or he may elect the option of having the computer program determine the most appropriate slide. A desired map is designated merely by including, as part of the display request, the ID of that particular slide. Once the geographical coordinates of all dynamic overlay data have been determined, the reference parametrics for the specified slide are recalled from data base storage to enable translation.

In the event the requester fails, either by oversight or choice, to specify a background projection, specialized coding is activated and a slide is automatically selected. Following compilation of the latitudes and longitudes of all the dynamic data to be displayed, a search of the slide library is initiated. Each slide capable of accommodating within its boundaries all data requested automatically becomes a candidate for slide selection. Final selection goes to the slide with the largest scale. Only Mercator and polar stereographic projections are considered for automatic slide selection, as the scale for Lambert projections differs, thus prohibiting comparison.

the future

The machine cycle time of a current-generation computer is measured in microseconds, and memory transfers occur in terms of nanoseconds. (A nanosecond is one thousandth of a microsecond or 10-9 second.) Yet a concerted effort is continually being expended by manufacturers to reduce total processing time, the slowest factor being input/ output (I/O). One proffered solution is the concept of multiprogramming, under which several programs reside in the computer concurrently. When the highest-priority job encounters a requirement for I/O, control passes to a second program, which operates until the I/O operation for the first is terminated. Should this task likewise encounter a request for I/O, a third program is initiated. Total processing time for a particular task may be slightly lengthened, but overall lapsed time for a "batch" of programs is significantly reduced, there being no lost time in the central processor. Larger core storage and expanded supervisors* are other areas currently under study and development.

*An expanded supervisor is a control program with increased capability to determine sequence of operation.

Although the computer, as it is known today, is comparatively new, third-generation machines are in production. As in the field of radio and television, such words as "microminiaturization" and "integrated circuitry" are becoming commonplace. Where once an immense console, with hundreds of flashing lights and alarms, was thought essential for monitoring the wizardry of the computer, there now stands a simple panel easily operated and monitored by one or two individuals.

Within the realm of maps, we find three-dimensional stereoscopic application on the horizon, as well as increased use of cathoderay tubes. Preliminary use of scanning techniques indicates a possibility of computer-generated map displays containing both static and dynamic information.  This would eliminate the need for a background projection such as is currently provided by the PSP.

The search for increased speed and emphasis on accessibility and retrievability of data are of particular interest to the proponents of computer command and control real-time systems, which are among the most complex data communication and processing systems in existence. High on our list of "wants" is development of a query language and data base organization that will grant wider latitude to a commander in retrieving data. More and more emphasis is also being placed on adoption, if not development, of a common language for command and control systems. As more systems come into being, the need for system compatibility becomes increasingly evident.

As I said, the need for command and control existed long before computers were even a figment of man's wildest fancy. This need will prevail as long as a requirement exists to maintain a force to achieve our national policy and objectives.

As for future potential, the major limitations to areas of computer application are the imagination of the user and financial resources.

Hq Strategic Air Command


1. From Maxim 77, as quoted in Thomas R. Phillips (ed.), Roots of Strategy (Harrisburg, Pa.: Military Publishing Co., 1940).

2. James T. Martin, Programming Real-Time Computer Systems (Englewood Cliffs, N.J.: Prentice-Hall, 1965), p. 4.

3. DODOD Programmer/Operator Manual, Vol. I, Hq SAC, 7 March 1966.


Major John A, Wohlman (B.S., University of Connecticut) is a systems analyst for the SAC Automated Command Control System. Commissioned through the ROTC program, he entered the Air Force in 1954 and attended Supply Officer School at Francis E. Warren AFB, Wyoming. Subsequently he served in the supply field with Tactical Air Command at Cannon AFB, New Mexico; then in Alaska, working first on materiel support for the Dew Line and then with the 5010th Air Base Wing at Eielson AFB, Alaska. In 1961 he was assigned to SAC's 80lst Combat Support Group at Lockbourne AFB, Ohio. After attending Squadron Officer School, he was sent to Offutt AFB, Nebraska. On completion of various programming and system schools, he was assigned to his present position with the Directorate of Command Control, DCS/O, Hq SAC. He has completed the Air Command and Staff Course by correspondence.


The conclusions and opinions expressed in this document are those of the author cultivated in the freedom of expression, academic environment of Air University. They do not reflect the official position of the U.S. Government, Department of Defense, the United States Air Force or the Air University.

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