ABSTRACT
There are generally three phases to the engagement and interception of a target. The first launch phase is usually uncontrolled. During this stage, the rocket motor is initiated and the missile is boosted up to its operating velocity in the direction of a target. This is followed by the midcourse phase if the missile is not locked onto the target. Usually, during this phase the missile is guided by radar into an area that allows it to lock onto the target with its own sensor. During the terminal (homing) guidance phase, the missile is guided onto the target using its local sensor measurements. Depending on the interceptor and mission, the terminal phase can begin anywhere from tens of seconds down to a few seconds before intercept. The purpose of the terminal phase is to remove the residual errors accumulated during the prior phases and ultimately to reduce the final distance between the interceptor and threat below some specified level. For systems that use a fuze and fragmentation warhead, this final miss distance must be less than the warhead lethal radius. A direct-hit missile can tolerate only very small “misses” relative to a selected aimpoint. In either case, during the terminal phase of flight the interceptor must have a high degree of accuracy and a quick reaction capability. Moreover, near the very end of the terminal phase (often referred to as the endgame), the interceptor may be required to maneuver to maximum capability in order to converge on and hit a fast-moving evasive target.
