Are air traffic controllers responsible for providing separation during resolution advisories (RAs)?

Air traffic controllers are not responsible for providing separation during resolution advisories (RAs). An RA is a situation that occurs specifically with regard to TCAS (Traffic Alert and Collision Avoidance System) used on commercial aircraft. When a TCAS RA is triggered, it is the pilot's responsibility to follow the guidance provided by the TCAS to avoid a potential collision.

This system is designed to enhance the safety of air traffic by alerting pilots to potential conflicts and giving instructions on how to maneuver to maintain safe distances from other aircraft. While air traffic controllers work to manage overall air traffic and maintain safe separation during normal operations, once an RA is activated, the pilots take over to execute the maneuver recommended by the TCAS. Thus, controllers rely on the pilots to resolve the conflict as per the RA, which is why they are not involved in separation responsibilities during these advisories.