When a TCAS resolution advisory is issued, what is the appropriate action and subsequent ATC notification?

• A. Inform ATC immediately but proceed as RA suggests
• B. Take RA action immediately and once conflict is resolved, return to the last ATC
• C. Take RA action immediately and remain at the new altitude; inform ATC as soon as possible
• D. Do not change altitude until ATC clearance

Answer: (B)

When a TCAS resolution advisory is issued, you must act on the RA immediately to maintain safe vertical separation from the intruder. The RA has priority over ATC clearance, so you don’t wait for ATC to approve the maneuver. After the conflict is resolved and the RA is no longer active, you should return to the altitude you were assigned by ATC (the last assigned altitude) as soon as it is safe to do so, and then coordinate with ATC as needed.

Why this is best: it emphasizes immediate safety—execute the RA right away to avoid a collision, then rejoin your ATC clearance by returning to the previously assigned altitude once the separation issue is resolved. Staying at the new altitude indefinitely would delay rejoining ATC and could complicate coordination. Waiting for ATC clearance before changing altitude would ignore the priority of the RA, which is designed to protect you during the encounter. Informing ATC is done as soon as practical after the RA is resolved, not as the RA is being executed.