Narrative:

I was vectoring an large transport for a straight-in visual approach to runway 9L. I had a widebody transport on downwind abeam the airport. I had the straight-in large transport on a 070 degree heading so I could put the widebody transport in ahead of the large transport (9L also). I turned the widebody transport left to 180 degree and descended the aircraft to 1500 ft (was out of about 5500 ft at this time). I turned the large transport left to 040 degree maintain 3000 ft and explained I was 'south' turning to follow company heavy jet. I then turned the widebody transport left to 100 degree. (Aircraft now out of about 4200 ft). Realizing separation was deteriorating I turned the large transport left to 360 degree and maintain 4000. Although the widebody transport acknowledged the left turn to 100 degree. The aircraft never turned. The large transport said he was receiving a TCASII 'RA' and was climbing. I ended up changing the widebody transport to runway 9R (aircraft was still heading south). Eliminating the conflict. Although I don't know this to be a fact, I suspect that when the widebody transport was heading 180 degree and I turned it to 100 degree, it was either studying the straight-in large transport on TCASII or was possibly receiving an 'RA' because the aircraft never made the left turn to 100 degree. Had the widebody transport turned when told, I still would have had to 'south' turn the large transport but there would have been no possible loss of separation. Also, when the widebody transport was heading 180 degree descending to 1500 ft, it leveled at 4000 ft for 3 mi further adding to me suspicion that a TCASII advisory made some poor vectoring on my part far worse than it would have been. Pilots should question TCASII traffic if they're concerned rather than 'doing their own thing.'

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Original NASA ASRS Text

Title: LGT HAD LTSS FROM WDB. TCASII RA. EVASIVE ACTION TAKEN.

Narrative: I WAS VECTORING AN LGT FOR A STRAIGHT-IN VISUAL APCH TO RWY 9L. I HAD A WDB ON DOWNWIND ABEAM THE ARPT. I HAD THE STRAIGHT-IN LGT ON A 070 DEG HDG SO I COULD PUT THE WDB IN AHEAD OF THE LGT (9L ALSO). I TURNED THE WDB L TO 180 DEG AND DSNDED THE ACFT TO 1500 FT (WAS OUT OF ABOUT 5500 FT AT THIS TIME). I TURNED THE LGT L TO 040 DEG MAINTAIN 3000 FT AND EXPLAINED I WAS 'S' TURNING TO FOLLOW COMPANY HVY JET. I THEN TURNED THE WDB L TO 100 DEG. (ACFT NOW OUT OF ABOUT 4200 FT). REALIZING SEPARATION WAS DETERIORATING I TURNED THE LGT L TO 360 DEG AND MAINTAIN 4000. ALTHOUGH THE WDB ACKNOWLEDGED THE L TURN TO 100 DEG. THE ACFT NEVER TURNED. THE LGT SAID HE WAS RECEIVING A TCASII 'RA' AND WAS CLBING. I ENDED UP CHANGING THE WDB TO RWY 9R (ACFT WAS STILL HDG S). ELIMINATING THE CONFLICT. ALTHOUGH I DON'T KNOW THIS TO BE A FACT, I SUSPECT THAT WHEN THE WDB WAS HDG 180 DEG AND I TURNED IT TO 100 DEG, IT WAS EITHER STUDYING THE STRAIGHT-IN LGT ON TCASII OR WAS POSSIBLY RECEIVING AN 'RA' BECAUSE THE ACFT NEVER MADE THE L TURN TO 100 DEG. HAD THE WDB TURNED WHEN TOLD, I STILL WOULD HAVE HAD TO 'S' TURN THE LGT BUT THERE WOULD HAVE BEEN NO POSSIBLE LOSS OF SEPARATION. ALSO, WHEN THE WDB WAS HDG 180 DEG DSNDING TO 1500 FT, IT LEVELED AT 4000 FT FOR 3 MI FURTHER ADDING TO ME SUSPICION THAT A TCASII ADVISORY MADE SOME POOR VECTORING ON MY PART FAR WORSE THAN IT WOULD HAVE BEEN. PLTS SHOULD QUESTION TCASII TFC IF THEY'RE CONCERNED RATHER THAN 'DOING THEIR OWN THING.'

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.