In this research, an analysis has been conducted on an air defense system that utilizes a combined and developed two-stage guidance model known as command-homing, by calculating the guidance errors. In this case, it is essential and unavoidable to discuss calculations and analyses related to the probability of a hit and the investigation of the impact of noise jamming on missiles, seekers, and ground radars. The discussion of the probability of the target's presence in the seeker's field of view and the probability of the target being detected by the seeker has not been addressed in other research. In this research, by presenting a regular geometric method and using the combined guidance method, this probability is calculated, and the effect is investigated, modeled, and simulated in total probability value. The simulation results and related analyses show that applying inputs and considering calculated errors can lead to a maximum hit probability of 6.0. Increasing the volume and impact of potential errors can decrease the hit probability to 5.0. This demonstrates that using this method allows for more detailed and accurate presentation of calculated probabilities. In simulations with noise jamming, it is evident that as the jammer's power increases, the hit probability decreases up to 3.0, and the functional range of the seeker decreases up to 10 km.