Narrative:

We were passing FL305 about to level off at our assigned altitude of FL310. Havana center called traffic at 12 O'clock. The mileage was indiscernible. Almost immediately thereafter, I picked up the traffic on TCASII, 12 O'clock position at FL310, inside of 10 NM. Uncomfortable with the situation, I increased the rate of climb substantially, increased power, and initiated a right turn 30+ degree angle of bank. TCASII turned yellow then quickly red with a subsequent RA calling for 'climb.' we visually picked up the target (possible DC9 or MD80) and it passed left and beneath us, estimating 500 ft below and 1-2 NM behind. I brought the traffic to the attention of havana center (133.7) and noted his altitude 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 passenger indicating a precautionary climb and turn to avoid an uncomfortable situation with oncoming traffic was made. Several passenger saw aircraft also, but none could identify either the type or company. Rest of flight routine.

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Original NASA ASRS Text

Title: 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.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.