POTENTIAL CONFLICT. THE FLC RECEIVES A TCASII RA ENRTE TO AN APCH AT SJU. THEY EVADE; BUT DO NOT SEE THE INTRUDER.

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PROCEEDING DIRECT DAXON ON APPROX HDG OF 190 DEGS AT ALT OF 15000 FT WHEN NOTICED CONFLICTING TFC ON TCASII SCOPE AT 20 MI APPROX 1000 FT ABOVE DSNDING. RELATIVE POS 11 O'CLOCK. WHEN OTHER ACFT APPROX 12 MI AND 300 FT ABOVE OUR ALT; YELLOW WARNING FOLLOWED BY RED WARNING AND 'DSND IMMEDIATELY' MESSAGE. HAVING OBSERVED IMPENDING PROB ON TCASII AND CLRING AREA TO R OF ACFT; BEGAN DSNDING R TURN UNTIL TCASII INDICATED NO FURTHER DSCNT NECESSARY. STOPPED DSCNT AND; WHEN ALERT ENDED; CLBED BACK TO 15000 FT AND DIRECT DAXON. PRIOR TO DSCNT; UNABLE TO PICK UP CONFLICTING TFC VISUALLY. WHEN TURN AND DSCNT BEGAN; NOTIFIED ATC OF ACTIONS BEING TAKEN DUE TO TCASII INSTRUCTIONS. TURN AND DSCNT WERE NOT NOTICED BY FLT ATTENDANTS SINCE TURN AND DSCNT ANTICIPATED. LOWEST ALT REACHED WAS 14300 FT; AND HDG CHANGE OF 30 DEGS MAX. NOT ABLE TO QUERY ATC AS TO INTENTIONS OF CONFLICTING TFC PRIOR TO TAKING AVOIDANCE ACTIONS. CONDITIONS WERE SPARKLING VFR WITH VISIBILITY UNLIMITED; HOWEVER; NEVER SAW CONFLICTING TFC AND ASSUME TFC WAS A SMALL ACFT. TCASII SHOWED TFC NEVER APCHED CLOSER THAN APPROX 6 OR 7 MI AT 10-11 O'CLOCK POS ON TCASII SCREEN. FREQ ATC WAS 124.75. I DON'T THINK THAT ACFT WOULD HAVE COLLIDED IF DSCNT AND TURN NOT MADE; BUT IT WOULD HAVE BEEN CLOSE. LOVE THAT TCASII!