2-22] INTERCEPTOR SYSTEM STUDY MODEL 101 



As before, the first step is to formulate a master plan for the analysis. 

 This master plan shows the fixed and variable elements of the interceptor 

 system problem; it must also show the method by which the problem can be 

 handled on a step by step (suboptimization) basis without losing the 

 relation of each step to the overall problem. Such a master plan is shown 

 in Fig. 2-26. It is merely a variant of the plans for steps 1 and 2 showing 

 the details of the interceptor weapons system analysis. 



The system effectiveness goal Pq, and the fixed elements of the system, 

 including AEW and vectoring system characteristics, have been derived or 

 defined in preceding analyses. These are shown in Fig. 2-26 as providing 

 the effectiveness criteria and inputs for the interceptor system analysis. 



The output of the system model is Pa (achieved). The variable elements 

 are manipulated in such a manner as to make Pa (achieved) equal Pa 

 (required). The combinations of variable element values for which this 

 condition is realized form the basis for the interceptor system specification. 



The separate steps of the interceptor system analysis can be derived from 

 the basic system logic and a careful consideration of the factors affecting 

 each phase of interceptor system performance. The interceptor reaching 

 the defense zone goes through three discrete phases in attacking a target 

 (see Fig. 2-9): (1) a vectoring phase which terminates in AI radar lock-on, 

 (2) a tracking phase which terminates in weapon launch, and (3) a missile 

 guidance phase which terminates in the destruction of the target. 



The performance in each phase of operation may be characterized by the 

 probability that — for a given set of fixed and variable elements — the 

 phase will be completely successful. These probabilities and the factors^^ 

 which determine their values are shown in Fig. 2-20 as: 



Pm = probability that the two-missile salvo will kill the specified target 

 (already specified as 0.75) 



Pc = probability that the interceptor will proceed from the point of 

 AI radar lock-on to a point where the missile salvo may be 

 launched with a kill probability of 0.75 



P„ = probability that the vectoring system will operate to bring the 

 interceptor to a position and orientation where it may detect, 

 identify, and lock on the target with its own AI radar. 



^^Only the most significant factors are shown for this hypothetical example. An actual 

 analysis might include many more. However, the same basic model would be applicable and 

 the approach to the problem — though more complicated mathematically — could be much 

 the same as will be used for this hypothetical example. Another important fact: Often It is 

 difficult to establish all of the vital factors affecting a given phase of system operation — some 

 of these are products of the analysis itself. This model has considerable flexibility in that such 

 additions can be made by simply reanalyzing the phase(s) affected. 



