The purpose of the research on Traffic Collision Avoidance System (TCAS) improvement capabilities for air traffic control is to determine major TCAS drawbacks and limitations, which can significantly affect flight safety, and to suggest possible theorems and methods in order to overcome these drawbacks and limitations. Taking into account implementation and work principle of TCAS, as well as work experience in air traffic control environment, major drawbacks and limitations, which can significantly affect flight safety, were determined and possible solution methods were suggested. As a result, the opportunity to downlink traffic advisories and resolution advisories from the aircraft to air traffic control systems was implemented, using secondary surveillance Mode S technique. Taking into account avionics development, it is possible to implement this feature in near future.