Final answer:
TCAS stands for Traffic Collision Avoidance System, which is used in aviation to prevent mid-air collisions by providing Traffic Advisories and Resolution Advisories to pilots.
Step-by-step explanation:
The initialism TCAS stands for Traffic Collision Avoidance System. It is an aircraft collision avoidance system designed to reduce the incidence of mid-air collisions between aircraft. TCAS monitors the airspace around an aircraft for other aircraft equipped with a corresponding active transponder, determines the location of these aircraft, and uses this information to warn pilots of potential collision risks. In case of a possible in-flight collision, TCAS issues either Traffic Advisories (TA) or Resolution Advisories (RA), where a TA alerts the pilot visually and audibly about other aircraft in the vicinity, and an RA provides explicit instructions to the pilot to climb, descend, maintain altitude, or adjust vertical speed to avoid a collision.