This paper presents a real-time conflict detection and resolution algorithm based on a probabilistic method. The approach uses a set of probability density functions that describe uncertainties from real time data bases such as ADS-B. To calculate the probability of conflict, we use probabilistic method by using geometric based Monte Carlo simulations that allow for reducing computation time considerably. From the probability of conflict obtained, threat level is determined between two aircraft, then, one of the possible resolution maneuver options is chosen which can minimize the probability of conflict. When the probability of conflict is in threat level zero, own aircraft is guided to the way-point. For guidance to the way-point, proportional navigation guidance law is used. The paper finishes with several multi-aircraft encounter simulations, illustrating the performance and properties of the proposed algorithm.