A method for engaging a hostile missile with an interceptor missile includes mathematically dividing an estimated target trajectory into portions, the junction of each portion with the next defining a possible intercept point. The engagement for each possible intercept point is modeled, to generate a probability of lethal object discrimination which is processed to generate a probability of intercept for each of the possible intercept points. The intercept point having the largest probability of intercept defines a selected intercept point from which intercept missile launch time is calculated, interceptor missile guidance is initialized, and the interceptor is launched at the calculated launch time and under the control of the interceptor missile guidance. Also, a method for estimating discrimination performance of a system of sensors includes generating sensor data signal-to-noise ratio and an aspect angle between the sensor and a lethal object. A table of probability of lethal object discrimination is generated as a function of the signal-to-noise ratio and aspect angle. The signal-to-noise ratio and the aspect angle are quantized into bins and the table with at least the signal-to-noise ratio and the aspect angle is entered to determine the probability of lethal object discrimination.