RPTED SIT OF A COMMUTER TURBOPROP AND AN ACR B737 CONVERGING AND DSNDING FROM THE SAME ALT RESULTING IN A LOSS OF SEPARATION AND BOTH ACFT REACTING TO TCASII RA EVASIVE ACTION COMMANDS. THE TURBOPROP CLBS AND THE B737 DSNDS.

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2 NM FROM NESTO INTXN; CLRED TO FLY HDG 300 DEGS; CROSS GRUNZ 6000 FT OR ABOVE AND CLRED ILS RWY 32 PIT. 1 MI R OF LOC AND 1 1/2 DEGS BELOW GS AT 6000 FT; ATC ISSUED A TURN TO 360 DEGS. WE HAD AN ACFT ON TCASII 10 MI RANGE APCHING FROM 11 O'CLOCK AND 200 FT ABOVE. DURING THE TURN TO 360 DEGS WE RECEIVED AN RA TO DSND WHICH WE FOLLOWED. WE NOTIFIED CTLR OF RA DSCNT AND HE SAID 'DO NOT DSND.' ACFT ON TCASII WAS STILL ONLY 200 FT ABOVE AND ALMOST MERGED WITH US. WE RECEIVED A REDUCED DSCNT FOLLOWED BY ANOTHER RA DSCNT. WE FOLLOWED SECOND RA AND ACFT PASSED 200 FT OVER TOP OF US; THEN A CLR OF CONFLICT WAS RECEIVED. INITIAL DSCNT WAS 800 FT TO APPROX 5200 FT AND SECOND DSCNT WAS TO AROUND 4600 FT. WE TALKED TO PIT APCH SUPVR ON GND AND HE SAID THE TFC WAS SUPPOSED TO TURN IN FRONT OF US ON APCH. HE SAID THE TFC WAS TURNING TOO SLOW. HE ALSO SAID THE COMMUTER PLT SAID HE RECEIVED AN RA CLB AT 5300 FT BUT WE NEVER SAW ANY EVIDENCE OF HIM CLBING. HE WAS FOLLOWING US DOWN. I FEEL THE TCASII SAVED A COLLISION. THE OTHER ACFT WAS ON A DIFFERENT FREQ SO WE COULD NOT HEAR HIM RESPOND TO THE CTLR. HE COULD NOT HEAR US GIVING AN RA DSCNT TO ATC EITHER. I DO NOT KNOW WHY THEY WERE USING DIFFERENT FREQ IN APCH ENVIRONMENT. ANOTHER POINT IS IF WE HAD LISTENED TO THE CTLR AND FOLLOWED HIS 'DO NOT DSND;' WE PROBABLY WOULD HAVE COLLIDED. THE SUPVR SAID WE WERE CORRECT IN FOLLOWING THE RA AND DID NOT KNOW HOW TO CLASSIFY THE INCIDENT. HE SAID IT WAS A TCASII PROB (?). I FEEL THE CTLR IS RESPONSIBLE FOR MAINTAINING SEPARATION. SUPPLEMENTAL INFO FROM ACN 385908: STILL CLOSING; ATC TURNS US TO A 360 DEG HDG. OUR RA REACTS AT ABOUT THE SAME TIME; 'DSND; DSND.' WE FOLLOW TCASII ORDER. WE NOTIFY ATC OF OUR RA DSCNT. IT APPEARED THAT OUR TARGETS MERGED ON OUR TCASII. DURING DSCNT THE TARGET STAYED ON TOP OF US INDICATING +200 FT. SUPPLEMENTAL INFO FROM ACN 385758: WHILE BEING RADAR VECTORED FOR THE ILS RWY 32 PIT; A TCASII RA WAS RECEIVED. OUR FLT WAS ASSIGNED A HDG OF 160 DEGS FOR A L DOWNWIND PATTERN TO PARALLEL THE LOC. ON THE W SIDE OF LOC THE OTHER ACFT; A B737; WAS BTWN GRUNZ AND WYLER ON THE RWY 32 LOC AT 6000 FT. WE WERE THEN GIVEN A HDG OF L TO 350 DEGS AND DSND FROM 6000 FT TO 4000 FT; EXPEDITE THROUGH 5000 FT. WHILE IN THE TURN PASSING THROUGH APPROX 5500 FT; A TA WAS RECEIVED; IMMEDIATELY FOLLOWED BY AN RA TO CLB. AS WE INITIATED A LEVELOFF FOLLOWED BY A CLB; WE NOTICED THAT THE B737 WAS ALSO DSNDING WITH US. WE CLBED TO APPROX 5700 FT AS THE B737 CONTINUED TO DSND RESOLVING THE CONFLICT. WE FEEL THE CONTRIBUTING FACTOR TO THIS EVENT WAS OUR ASSIGNED TURN TO 350 DEGS DIRECTLY TOWARDS THE B737 WITHOUT THE VERT SEPARATION.