The efficiency of the anti-aircraft guided missile does not depend only upon the correct choice of the guidance and control systems, but also upon the correct choice of the warhead explosion instant. Large projectiles and all surface-to-air missiles carry warheads. There are many types of warheads. The fragmentation type is usually used in the surface-to-air missiles. A fuse is required in all projectiles and missiles equipped with warheads. There are different types of proximity fuses, but the radio fuse type is almost usually used for the anti-aircraft missiles. It reacts on the reflected radio signals from the engaged target and makes the warhead explodes within the effective distance from the target. The optimum operation of the fusing system results in maximum probability of target destruction. That situation is achieved by the complete coincidence between the fuse activation zone and the target destruction zone. The radio fuse activation zone is determined by the fuse antenna radiation pattern. However, the target destruction zone is determined by the relative velocities of the fragments with respect to the target velocity in the space. This coincidence is verified by different techniques as varying the initiation instant of the warhead, moving the radio fuse antenna radiation pattern in the space, changing the pyrotechnic exploder position on the warhead detonation tube, and rotating the warhead around an axis perpendicular to the missile longitudinal axis. In this paper, the variation of the explosion instant of the warhead is discussed. A computational algorithm is developed to solve the mathematical model of a typical anti-aircraft radio fusing and arming systems. A computer code written with C language is then built to obtain numerical results. The number of fragments that hit the target, which is taken as a measure to the kill probability, is calculated for various engagement geometries. The effect of the final miss distance and missile and target velocities on the destruction probability level is computed. Results show that with a RC integrating circuit being employed as a decision circuit, reasonable destruction probability can be achieved for a wide variety of engagement scenarios. However better results can be achieved with more intelligent circuits being employed.