Abstract: The kill probability calculating models of one-missile to one-target for the gimbaled warhead, which is designed to fire the fragments in the target direction, are studied in order to optimize lethality. Two encounter concepts of side-attack and forward-intercept at endgame are formulated in the missile coordinate system. The kill probability is calculated using Monte-Carlo method. Based on the circular spray pattern with uniform pattern density, the optimum lethal radius is established for forward-intercept concept. And then the effects of missile-target relative velocity and miss distance on kill probability are analyzed. According to the study, the preferred conditions for side-attack or forward-intercept are proposed: if v_r≥1 700 m/s and ρ≤2.5 m or v_r≥3 000 m/s and ρ≤4 m，then the encounter concept of forward-intercept is preferable; In other cases, the encounter concept of side-attack is preferable.

Key words: ordnance science and technology, anti-aircraft missile, guidance integrated fuze, gimbaled warhead, coordination of fuze and warhead, kill probability