Abstract: Operational effectiveness analysis of aircraft is one of the important research texts on military equipment. The determining methods of accessible zone of airborne air-to-surface missile and first attacking probability are described. The mathematical models are established to describe operational effectiveness of a single and a group aircraft attacking targets during combat sortie. The calculating methods of the probability that a target is killed and the probability that an aircraft is killed in the phase of attack are presented. The formulas to be used to calculate the average killed number of targets for one aircraft and the probability that a group aircraft is killed during combat sortie are deduced. The foundation has been established for assessments of multistep air-to-surface attacking action.