PIT APCH CTLR VECTORING 2 ACFT FOR SAME RWY CLRS ACFT X AT THE LOWER ALT TO DSND. ACFT Y; 2000 FT HIGHER; IS ALSO GIVEN A DSCNT BUT IS STOPPED WHEN ACFT X RECEIVED A TCASII RA AND STARTS A CLB.

Narrative

ACFT X WAS HANDED OFF TO ME AT 7000 FT. ACFT Y WAS HANDED OFF AT 9000 FT. THE 2 ACFT WERE CLOSE LATERALLY AND GOING TO LAND ON THE SAME RWY 32. I SPLIT THEM UP WITH DIVERGENT HEADINGS AND THEN I ISSUED A DSCNT TO 6000 FT TO ACFT X. I OBSERVED THE ACFT X DSND OUT OF 7000 FT AND I THEN GAVE DSCNT CLRNC TO THE ACFT Y. I ASSIGNED HIM 7000 FT. AS THE ACFT X MODE C READ 6500 FT; HE ADVISED ME HE HAD AN RA AND WAS CLBING. I TOLD HIM ABOUT THE ACFT Y AND QUICKLY STOPPED THE ACFT Y'S DSCNT. I THEN TURNED THE ACFT X AWAY FROM THE ACFT Y. AFTER A LITTLE SCRAMBLING AND RESEQUENCING THE ACFT X PLT EXPLAINED THE TCASII SAW SOMETHING BELOW HIM AND GAVE A CLB RA. I DIDN'T SEE ANY TFC ANYWHERE THEY WOULD HAVE CONFLICTED WITH HIM BEFORE OR AFTER. THE ACFT X PLT ADMITTED HE COULDN'T FIND OR SEE THE TFC EITHER OUT THE WINDOW OR ON TCASII AFTER ALL THE FUN WAS OVER. THAT ACFT Y DIDN'T GET BELOW 8300 FT AND THE ACFT X NEVER GOT ABOVE 7000 FT. THOSE 2 AIRPLANES WOULD HAVE GOTTEN TOO CLOSE WITHOUT IMMEDIATE INTERVENTION. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: CONVERSATION WITH RPTR DID NOT ADD ANY NEW INFO ON THE TCASII INCIDENT. I DID TELL THE CTLR RPTR THAT IT WAS VERY EVIDENT THAT HIS QUICK ACTION TO MAINTAIN SEPARATION MAY HAVE PREVENTED A SERIOUS CONFLICT FROM OCCURRING.