Traffic Collision Avoidance System

A Traffic Collision Avoidance System (TCAS) is an aircraft system designed to reduce mid-air collisions by monitoring the airspace around an aircraft for other transponder-equipped aircraft and warning pilots of potential threats. TCAS is mandated by the International Civil Aviation Organization for aircraft with a maximum take-off mass over 5,700 kg or carrying more than 19 passengers. The system uses secondary surveillance radar transponder signals to provide advice to pilots on potentially conflicting aircraft, and has been developed through industry and agency efforts since the 1950s, with the first certification of TCAS II in 1987.learn more on wikipedia