ALTDEV DUE TO TCASII RA.

Narrative

WE WERE LEVEL AT FL260 IN THE CLOUDS ENRTE DIRECT BOILER (BVT) VOR. ZID (133.05) ISSUED US TFC AT 11 O'CLOCK DSNDING TO FL270. WE BOTH LOOKED AT THE TCASII SCOPE; AND SAW THE TFC SHOWING A PLUS 12 DSNDING. IT THEN WENT TO A PLUS 11 DSNDING; PLUS 10 DSNDING; PLUS 9 DSNDING AND STILL DSNDING. I TOLD THE FO IF IT GOT TO A PLUS 800 TO ASK THE CTR WHAT WAS HAPPENING. WE THEN GOT THE AURAL WARNING 'TFC; TFC.' THE FO STARTED TO CALL THE CTR WHEN WE GOT 'DSND; DSND.' I DISENGAGED THE AUTOPLT AND NOSED OVER TO KEEP OUT OF THE RED ARC ON THE IVSI. THE FO NOTIFIED CTR WE WERE DSNDING TO A TCASII RA. THE NEXT AURAL WARNING WAS MONITOR DSCNT AND THEN EVENTUALLY CLR OF TFC. WE THEN CLBED BACK UP TO OUR ASSIGNED ALT FL260. DURING THIS RA; THE CLOSEST WE NOTICED THE OTHER ACFT WAS AT PLUS 600 FT; WE HAD DSNDED DOWN TO 25400 FT DURING THE RA AND THE FO SAID THAT AT 25400 FT; SHE NOTICED THE TARGET ON THE TCASII SCOPE WAS NOW AT PLUS 1400 AND SHOWING A CLB. ONCE WE WERE LEVEL; WE ASKED THE CTR AGAIN IF THEY UNDERSTOOD WE DSNDED DUE TO A TCASII RA AND THEY SAID YES. THEY ALSO SAID THEY HAD NO PROB WITH IT. ON THE NEXT ZID FREQ THE CTLR OR SUPVR ASKED US IF WE HAD RESPONDED TO AN RA ON THE PREVIOUS FREQ AND WE SAID YES. I THEN SPOKE WITH OUR DISPATCH AND TOLD THEM WHAT HAD OCCURRED AND ASKED THEM TO TALK WITH ZID AND FIND OUT WHAT THEY SAW. I CALLED DISPATCH ONCE WE WERE ON THE GND AND THEY SAID THEY SPOKE WITH THE SUPVR AT ZID. I BELIEVE THE DISPATCHER SAID THAT THE CTR HAD SHOWN THE OTHER FLT WITHIN 600 FT OF US; HOWEVER; THE OTHER FLT SAID THEY WERE LEVEL AT 27000 FT THE WHOLE TIME. I AM A NEW CAPT IN THE ACFT AND HAVE BEEN WITH THE AIRLINE FOR 7 YRS. WE FOLLOWED THE PROC EXACTLY AS WE WERE TAUGHT AND BELIEVE TCASII TO BE A VERY VALUABLE TOOL IN PREVENTING MIDAIR COLLISIONS. EVEN THOUGH WE NEVER SAW THE OTHER ACFT I AM CONVINCED IT PREVENTED A NEAR TRAGIC INCIDENT.