This paper presents a comprehensive study regarding optimization method for aircraft collision avoidance. The analysis is performed from the standpoint of collision risk as key performance indicator. Appropriate advisories are obtained in case of an aircraft equipped with Traffic Alert and Collision Avoidance System – TCAS. For real-time simulations, multiple aircraft operations are being used and complex models are consequently enabling the safety analysis in order to be completed.  Significant improvements can be related with the trajectory model templates on which TCAS is relying its predictions. TCAS uses a decision-making process, defined by two steps. The first step consists in system prediction of the current situation of air traffic, assuming that both aircraft continue their flight forthright, without acceleration. The system’s capabilities to assess the incoming aircraft trajectories and to release advisories on the nominal template, enabling collision avoidance. The second step, justified by the necessity to avoid nuisance alerts, consists in correcting the trajectories evolutions which must be performed to the initial trajectory prediction.

That incertitude excludes TCAS from becoming precise collision avoidance in decisions of more than 30 to 40 seconds into the futurity. TCAS can choose other avoidance models and will train the pilot to execute the recommended maneuver; in this case the predicted segregation between aircraft is not adequate. The correctness for acquirement the safety of the two-step system contains in tuning the alerting parameters. Such as, on balance, first-step alerts are emitting early adequate that high avoidance trajectories to hold on. A bulk of the traffic displays to provide the pilot the capability to choose multiple ranges and to choose the altitude band for displayed traffic. These abilities permit the pilot to display traffic on longer ranges and with major altitude separation when in cruise flight, when retaining the capability to choose lower display ranges in terminal zone to reduce the total of display clutter.