B757 FLC INITIATE TCASII EVASIVE MANEUVER IN MUFH AIRSPACE DUE TO CONFLICTING DC9 AT SAME ALT; OPPOSITE DIRECTION.

Narrative

WE WERE PASSING FL305 ABOUT TO LEVEL OFF AT OUR ASSIGNED ALT OF FL310. HAVANA CTR CALLED TFC AT 12 O'CLOCK. THE MILEAGE WAS INDISCERNIBLE. ALMOST IMMEDIATELY THEREAFTER; I PICKED UP THE TFC ON TCASII; 12 O'CLOCK POS AT FL310; INSIDE OF 10 NM. UNCOMFORTABLE WITH THE SIT; I INCREASED THE RATE OF CLB SUBSTANTIALLY; INCREASED PWR; AND INITIATED A R TURN 30+ DEG ANGLE OF BANK. TCASII TURNED YELLOW THEN QUICKLY RED WITH A SUBSEQUENT RA CALLING FOR 'CLB.' WE VISUALLY PICKED UP THE TARGET (POSSIBLE DC9 OR MD80) AND IT PASSED L AND BENEATH US; ESTIMATING 500 FT BELOW AND 1-2 NM BEHIND. I BROUGHT THE TFC TO THE ATTN OF HAVANA CTR (133.7) AND NOTED HIS ALT WAS FL310. HAVANA REPLIED 'STANDBY...(PAUSE)...IT WAS A MISTAKE; SORRY.' WE TOPPED OUT AT ABOUT FL323 AND RETURNED TO UA877 AND FL310. A LENGTHY PA TO PAX INDICATING A PRECAUTIONARY CLB AND TURN TO AVOID AN UNCOMFORTABLE SIT WITH ONCOMING TFC WAS MADE. SEVERAL PAX SAW ACFT ALSO; BUT NONE COULD IDENT EITHER THE TYPE OR COMPANY. REST OF FLT ROUTINE.