APCH CTLR VECTORING A B757 FOR APCH DSNDED THE ACFT TO 6000 FT WHEN HE SAW A B737 WORKING WITH ADJACENT ARR CTLR APPEAR TO LEAVE 6000 FT. ON A SECOND SCAN HE SAW THAT THE B737 WAS STILL AT 6000 FT AND ACFT WERE CONVERGING; SO HE CLBED THE B757 TO 7000 FT. THE B757 GOT A TCASII RA TO DSND; BUT IGNORED IT AS HE WAS ALREADY CLBING AND IN THE TURN THE CTLR HAD GIVEN HIM. LTSS OCCURRED.

Narrative

WHILE VECTORING NUMEROUS ACFT THROUGH A LINE OF HVY TSTMS; I RECEIVED A POINTOUT FOR ACR Y; B737; AT 6000 FT TO DSND TO 3000 FT. WORKLOAD WAS HVY AS PLTS WERE CONSTANTLY INQUIRING ABOUT WX CONDITIONS; REQUESTS FOR DEV; ETC. I OBSERVED ACR Y MODE C AT 5800 FT WHILE SCANNING AND AFTER DETERMINING A DSCNT WAS OCCURRING PROCEED TO CLR MY ARRS INCLUDING ACR X; B757; TO 6000 FT. SIT DEVELOPED BECAUSE OTHER ARR CTLR WAS SIMILARLY OVERWHELMED BY WORKLOAD AND FAILED TO ISSUE FURTHER DSCNT CLRNC IN A TIMELY MANNER TO ACR Y. THIS WAS COMPOUNDED BY A MODE C FLUCTUATION WHICH APPEARED TO INDICATE A DSCNT. WHEN I OBSERVED THE CONFLICT; ACFT WERE ON 60 DEG CONVERGING PATH. I ISSUED A TURN AND CLB TO ACR X TO ESTABLISH SEPARATION. CONFLICT ALERT WENT OFF AFTER TARGETS WERE SEPARATED BY COURSE DIVERGENCE. THE LESSON HERE I BELIEVE IS TO RESIST THE URGE TO CONTINUE TO RUN TFC AT A NORMAL VOLUME WHEN ABNORMAL METEOROLOGICAL CONDITIONS CREATE A HIGH WORKLOAD ENVIRONMENT. SUPPLEMENTAL INFO FROM ACN 341365: WE WERE ASSIGNED; AND AT; 6000 FT ON A 170 DEG HDG; APPROX 10 MI N OF SPEEZ INTXN. APCH THEN ISSUED AN IMMEDIATE CLRNC TO CLB TO 7000 FT AND L TURN TO 090 DEGS. AT THE SAME TIME WE STARTED THE CLB THE TCASII GAVE US AN RA AT 100 FT ABOVE US; AND TOLD US TO DSND. HOWEVER; WE WERE ALREADY ESTABLISHED IN THE CLB AND VERY SHORTLY THE TCASII CHANGED TO DON'T DSND. WE REACHED 6500 FT AS THE OTHER ACFT PASSED 1 1/2 MI BEHIND AND 1000 FT BELOW US; AS SEEN ON TCASII AND CONFIRMED BY ATC LATER ON THE PHONE. AFTER LNDG; THE ATC SUPVR RELAYED TO THE CAPT; THAT THE CTLR HAD USED POOR JUDGEMENT. WHEN HE NOTICED THE ACFT TOO CLOSE HE GAVE US THE CLB TO 7000 FT AND THE OTHER ACFT A DSCNT TO 5000 FT. WE NEVER VISUALLY SAW THE OTHER ACFT AS WE WERE IMC. ALSO THE TCASII ALLOWED US TO SEE THE POS OF THE OTHER ACFT; BUT BECAUSE WE HAD ALREADY RECEIVED A CLRNC TO AVOID THE ACFT; THE TCASII CORRECTION WAS A NUISANCE.