When informed that an aircraft is responding to a TCAS Resolution Advisory (RA), do NOT ___?

• A. issue control instructions contrary to that advisory
• B. issue control instructions
• C. clear the aircraft to land until the RA is no longer in effect
• D. transfer control of the aircraft to another controller

Answer: (A)

TCAS RA commands are created to prevent a potential collision and have priority over any ATC guidance. When a pilot is responding to an RA, they will follow the RA to maintain safe separation, even if ATC instructions would suggest a different action. Because of that, a controller must not issue control instructions that contradict the advisory. Doing so could undermine the safety maneuver the RA is enforcing.

You can issue instructions that do not conflict with the RA, and coordination should continue as appropriate. Transferring control to another controller isn’t inherently conflicting with the RA. Clearing to land while the RA is still active could put the aircraft on a path that conflicts with the RA, so that should wait until the advisory is no longer in effect.