ACR X WRONG ALTIMETER SET HAD TCASII RA DSNDED TO OCCUPIED ALT HAD LTSS FROM ACR Y. PLTDEV. ERRONEOUS TCASII RA.

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ACR X WHILE OPERATING AT A LEVEL CRUISING ALT OF 29000 FT; OUR TA AND COLLISION AVOIDANCE SYS (TCASII) SHOWED A TA ALERTING US TO ANOTHER ACFT LEVEL AT OUR ALT AND CONVERGING UPON OUR POS. THE TA QUICKLY CHANGED TO AN RA INDICATING A COLLISION THREAT AND DEMANDING IMMEDIATE CORRECTIVE ACTION. A VISUAL SIGHTING OF THE INTRUDING ACR Y CONFIRMED TO US THAT WE NEEDED EVASIVE ACTION. WE IMMEDIATELY BEGAN A TURN AWAY FROM THE ACFT AND DSNDED TO 28200 FT TO AVOID THE OTHER ACFT WHICH PASSED APPROX 1/2 MI FROM OUR POS. JUST PRIOR TO OUR CORRECTIVE ACTION; WE WERE ASSIGNED A NEW FREQ BY ZDC. WE HAD JUST CHANGED TO THIS NEW FREQ WHEN THE TFC CONFLICT OCCURRED. DURING OUR CORRECTIVE ACTION; WE MADE NUMEROUS UNANSWERED CALLS ON THIS NEW FREQ IN AN ATTEMPT TO INFORM ATC OF OUR ACTIONS. WITH NO RESPONSE ON OUR NEW FREQ; WE RPTED OUR ACTIONS ON OUR OLD FREQ. AFTER THIS CONFLICT WAS RESOLVED AND ON OUR CLB BACK TO 29000 FT; WE NOTED THAT OUR ALTIMETERS WERE SET AT 30.14 INSTEAD OF 29.92 RESULTING IN A 200 FT ERROR. WE CORRECTED OUR ALTIMETERS. SUPPLEMENTAL INFO FROM ACN 219984: ACR X APPARENTLY HAD AN IMPROPER TCASII RESOLUTION TO DSND FROM 29000 FT. HE ADVISED ATC HE WAS TAKING EVASIVE ACTION AND DSNDED THROUGH 28000 FT. HE WAS NEBOUND WHEN WE VISUALLY PICKED HIM UP. OUR TURN TOWARDS PXT VOR WAS STOPPED AND WE PASSED BEHIND HIM. NO EVASIVE MANEUVERS WERE PERFORMED; BANK ANGLES DID NOT EXCEED 15 DEGS. OUR ACFT WAS NOT TCASII EQUIPPED.