2-12] 



AEW DETECTION RANGE REQUIREMENTS 



73 



Fixed Reference Direction 

 (e.g. North) 



Fig. 2-17 Collision Vectoring Geometry. 



Vp, the interceptor will close with the target in the shortest possible 

 time if the following relationship is satisfied: 



sin L = {Vt IVp) sin Oj 



(2-4) 



where each of the variables may be defined from the figure. 



The quantities, dr, V-r, and Bls are obtained from the AEW and CIC 

 systems and transmitted to the interceptor. A computer in the interceptor 

 uses this information along with its measurement of its own velocity Vp 

 to calculate the proper lead angle L. Then, it adds this angle to the space 

 line-of-sight direction, 6 is, to obtain the desired space heading of the inter- 

 ceptor. The pilot flies the aircraft to maintain this heading and commences 

 to search for the target with his AI radar oriented along the line of sight. 



Target altitude also is transmitted to the interceptor. The interceptor 

 climbs to this altitude using his altimeter as a reference. In the hypothetical 

 system, vectoring guidance information is transmitted at a rate equal to 

 the scanning rate of the AEW fan-beam radars. Vectoring guidance is 

 continued until the interceptor acquires the target with its own AI radar. 



The choice of this vectoring technique has a profound effect on the inter- 

 related requirements of the interceptor AI radar and the AEW and CIC 

 systems. A further description of the vectoring problem and the manner 

 by which vectoring errors affect AI radar requirements is contained in 

 Paragraph 2-25. 



2-12 AEW DETECTION RANGE REQUIREMENTS 



The foregoing discussion has established that an early warning range of 

 255 n.mi. is compatible with the system effectiveness goal and the assumed 

 fixed elements of the problem. 



It has been assumed that the early warning coverage need be provided 

 only in the area of most likely attack. The operational doctrine established 

 that a calculated risk would be taken that the defined mass attack would 



