OBJECTIVES: At the conclusion of this chapter the student will:
1. Understand the basic purpose of any weapon system through an analysis of the Fire Control Problem.
2. Be able to identify and explain the six fundamental steps/tasks that comprise the Fire Control Problem.
3. Understand the basic concepts of the "detect to engage" sequence.
4. Be familiar with the basic components that comprise a modern weapons system.
The international situation has deteriorated and the United States and Nation X have suspended diplomatic relations. The ruler of Nation X has threatened to annex the smaller countries bordering Nation X and has threatened hostilities toward any country that tries to stop him. You are assigned to a guided missile cruiser which is a member of Battle Group Zulu, currently stationed approximately 300 nautical miles off the coast of Nation X. The Battle Group Commander has placed the Battle Group on alert by specifying the Warning Status as Yellow, in all warfare areas, meaning that hostilities are probable.
You are standing watch as the Tactical Action Officer (TAO) in the Combat Information Center (CIC), the nerve center for the ship's weapons systems. Dozens of displays indicate the activity of ships and aircraft in the vicinity of the Battle Group. As the TAO you are responsible for the proper employment of the ship's weapons systems in the absence of the Commanding Officer. It is 0200 and you are in charge of a multi-million dollar weapon system and responsible for the lives and welfare of your shipmates.
The relative quiet of CIC is shattered by an alarm on your Electronic Warfare (EW) equipment indicating the initial detection and identification of a possible incoming threat by your Electronic Support Measures (ESM) equipment. The wideband ESM receiver detects an electromagnetic emission on a bearing in the direction of Nation X. Almost instantaneously the emitter's parameters are interpreted by the equipment and compared with radar parameters stored in the memory of the ESM equipment. On a display screen the information and a symbol indicating the emitter's approximate line of bearing from your ship is presented. You notify the Commanding Officer of this new development. Meanwhile the information is transmitted to the rest of the Battle Group via radio data links.
Moments later, in another section of CIC, the ship's long range two-dimensional air search radar is just beginning to pick up a faint return at the radar's maximum range. The information from the air search radar coupled with the line of bearing from your ESM allow you to localize the contact and determine an accurate range and bearing. Information continues to arrive, as the ESM equipment classifies the J-band emission as belonging to a Nation X attack aircraft capable of carrying anti-ship cruise missiles.
The contact continues inbound, headed toward the Battle Group, and within minutes is within range of your ship's three-dimensional search and track radar. The contact's bearing, range, and altitude are plotted to give an accurate course and speed. The range resolution of the pulse compressed radar allows you to determine that the target is probably just one aircraft. You continue to track the contact as you ponder your next move.
As the aircraft approaches the outer edge of its air launched cruise missile's (ALCM) range, the ESM operator reports that aircraft's radar sweep has changed from a search pattern to a single target track mode, indicating imminent launch of a missile. In accordance with the Rules of Engagement (ROE) in effect, you have determined that this action shows hostile intent on the part of the target, and decide to defend the ship against immienent attack. You inform your CIC team of your intentions, and select a weapon, in this case a surface to air missile, to engage the target. You also inform the Anti-Air Warfare Commander of the indications of hostile intent, and he places you and the other ships in Air Warning Red, attack in progress.
As the target closes to the maximum range of your weapon system, the fire control or tactical computer program, using target course and speed, computes a predicted intercept point (PIP) inside the missile engagement envelope. This information is and the report that the weapon system has locked on the target is reported to you. You authorize batteries released and the missile is launched toward the PIP. As the missile speeds towards its target at Mach 2+, the ship's sensors continue to track both the aircraft and the missile. Guidance commands are sent to the missile to keep it on course.
Onboard the enemy aircraft, the pilot is preparing to launch an ALCM when his ESM equipment indicates he is being engaged. This warning comes with but precious few seconds, as the missile enters the terminal phase of its guidance. In a desperate attempt to break the radar lock he employs evasive maneuvering. It's too late though, as the missile approaches the lethal "kill radius," the proximity fuze on the missile's warhead detonates its explosive charge sending fragments out in every direction, destroying or neutralizing the target. This information is confirmed by your ship's sensors. The radar continues to track the target as it falls into the sea and the ESM equipment goes silent.
The Fire Control Problem
What has just been described above is not something out of a war novel, but rather a scenario of a possible engagement between a hostile force (the enemy attack aircraft) and a Naval Weapons System (the ship). This scenario illustrates the concept of the "detect to engage" sequence, which is an integral part of the modern Fire Control Problem. Although the scenario was one of a surface ship against an air target, every weapon system performs the same functions: target detection, resolution or localization, classification, tracking, weapon selection, and ultimately neutralization. In warfare, these functions are accomplished from submarines, aircraft, tanks and even Marine infantrymen. The target may be either stationary or mobile; it may travel in space, through the air, on the ground or surface of the sea, or even beneath the sea. It may be manned or unmanned, guided or unguided, maneuverable or in a fixed trajectory. It may travel at speeds that range from a few knots to several times the speed of sound.
The term weapons system is a generalization encompassing a broad spectrum of components and subsystems. These components range from simple devices, operated manually by a single man, accomplishing one specific function, to a complex array of subsystems, interconnected by computers, and data communication links that are capable of performing several functions or engaging numerous targets simultaneously. Although each subsystem may be specifically designed to solve a particular part of the fire control problem, it is these components operating in concert that allows the whole system to achieve its ultimate goal - the neutralization of the target.
All modern naval weapons systems, regardless of the medium they operate in or the type of weapon they employ, consist of the basic components that allow the system to detect, track and engage the target. Sensor components must be designed for the environments in which the weapon system and the target operate. These components must also be capable of coping with widely varying target characteristics, including target range, bearing, speed, heading, size and aspect.
Detecting the Target
There are three phases involved in target detection by a weapons system. The first phase is surveillance and detection, the purpose of which is to search a predetermined area for a target and detect its presence. This may be accomplished actively, by sending energy out into the medium and waiting for the reflected energy to return, as in radar, and/or passively, by receiving energy being emitted by the target, as by ESM in our scenario. The second phase is to measure or localize the target's position more accurately and by a series of such measurements estimate its behavior or motion relative to ownship. This is accomplished by repeatedly determining the target's range, bearing, and depth or elevation. Finally, the target must be classified, that is, its behavior must be interpreted so as to estimate its type, number, size and most importantly identity. The capabilities of weapon system sensors are measured by the maximum range at which they can reliably detect a target and their ability to distinguish individual targets in a multi-target group. In addition, sensor subsystems must be able to detect targets in a medium cluttered with noise, which is any energy sensed other than that attributed to a target. Such noise or clutter is always present in the environment due to reflections from rain or the earth's surface or as a result of deliberate radio interference or jamming. It is also generated within the electronic circuitry of the detecting device.
Tracking the Target
Sensing the presence of a target is an essential first step to the solution of the fire control problem. To successfully engage the target and solve the problem, updates as to the target's position and its velocity relative to the weapon system must be known or estimated continuously. This information is used to both evaluate the threat represented by the target and to predict the target's future position and a weapon intercept point so the weapon can be accurately aimed and controlled. In order to obtain target trajectory information, methods must be devised to enable the sensor to follow or track the target. This control or "aiming" may be accomplished by a collection of motors and position sensing devices called a servo system. Inherent in the servo process is a concept called feedback. In general, feedback provides the system with the difference between where the sensor is pointing and where the target is actually located. This difference is called system error. The system then takes the error and through a series of electro-mechanical devices moves the sensor and/or weapon launcher in the proper direction and at a rate such that the error is reduced. It is the goal of any tracking system to reduce this error to zero. Realistically this isn't possible so when the error is minimal the sensor is then said to be "on target." Sensor and launcher positions are typically determined by devices that are used to convert mechanical motion to electrical signals. Synchro transformers and optical encoders are commonly used in servo systems to detect the position and control the movement of power drives and indicating devices. The power drives then move the radar antennas, directors, gun mounts, and missile launchers.
The scenario presented in the beginning of this chapter was in response to a single target. In reality, this is rarely the case. The modern "battlefield" is one in which sensors are detecting numerous contacts, friendly and hostile, and information is continually being gathered on all of them. The extremely high speed, precision, and flexibility of modern computers enable the weapons systems and their operators to compile, coordinate, evaluate the data, and then initiate an appropriate response. Special-purpose and general-purpose computers enable a weapons system to detect, track, and predict target motion automatically. These establish the target's presence and define how, when, and with what weapon the target will be engaged.
Engaging the Target
Effective engagement and neutralization of the target requires that a destructive mechanism, in this case a warhead, be delivered to the vicinity of the target. How close to the target a warhead must be delivered depends on the type of warhead and the type of target. In delivering the warhead, the aiming, launch, and type of propulsion system of a weapon, and the forces which the weapon are subjected to enroute to the target need to be considered. The weapon's capability to be guided or controlled after launch dramatically increases its accuracy and probability of kill from a single weapon. The use of guidance systems also dramatically complicates system designs. These factors as well as the explosive to be used, the fuzing mechanism, and warhead design are all factors in the design and effectiveness of a modern weapon.
As can be seen, solving the fire control problem, from target detection to neutralization, requires a complex integration of numerous components which must operate together to achieve the goal. At the functional center of every weapon system is a human being, who is engaged in the employment of that system. Today's high technology naval weapons systems require that a Naval/Marine Corps Officer be competent in the scientific and engineering principles that underlie their design, operation and employment. Understanding the basic rules for evaluating or predicting a weapon system's performance are necessary as an aid to the imaginative use of tactics. Unless every weapons system operator possesses a thorough understanding of the physical processes that define the performance of equipment, our operating forces will be unable to make full use of their assets and exploit the weaknesses and limitations of the enemy.
1. List and briefly explain the six tasks that must be resolved in order to solve the Fire Control Problem.
2. What are the two basic ways in which a sensor initially detects the presence of a target? Give an example of each.
3. What are the two ways a detecting device's (sensor) capability is measured?