At presentthe estimation to the fighter aircraft capability is developed from function concerning to efficacy concerningand how to evaluate the operational effectiveness of the aircrafts in air combat has been explored for a long time.The air combat process is resolved into two parts of beyondvisualrange and withinvisualrange air combat according to the mode of modern air combatand operational effectiveness of the fighter aircraft is evaluated respectively.In allusion to stealth fighterthe radar detection abilitypassive radar detection ability and infrared detection ability are put forward as indexes of situational awareness ability for beyondvisualrange air combat.Analytic hierarchy process is used for operational effectiveness evaluation to both the beyondvisualrange and within visualrange air combatand the ability models are presented.