TCAS is a special system designed to reduce the incidence of mid-air collisions between aircraft.
It is also known as ACAS (Airborne Collision Avoidance System)
TCAS system capable of displaying conflicting traffic and providing resolution advice.
TCAS monitors the airspace around an aircraft for other aircraft equipped (independent of ATC)
TCAS warns pilots of the presence of other aircraft (transponder-equipped) which may present a threat of mid-air collision (MAC).
Intended as a last resort protection against risk of collision.
According to ICAO, TCAS is mandatory for all aircraft with MTOW (maximum take-off weight) over 5700 kg or carry more than 19 passengers