Narrative:

Efp = east feeder radar, nfr = north feeder radar. I was working efr. Small aircraft X was at 5000 ft nebound. Nfr was working air carrier Y swbound at 4000 ft. Air carrier Y advised he was climbing for TCASII (he was over an area where fish spotter aircraft normally fly at low altitudes). The nfr controller advised me of air carrier Y climb and I issued a climb to small aircraft X and the reason for climb. Small aircraft X advised he had air carrier Y in sight and was told to maintain visual separation. Small aircraft X later said that even without visual separation that my instructions would have avoided a problem. I feel that even without my instructions the aircraft would have missed, but not by much and on radar the aircraft targets would have touched. Air carrier Y reacted to a TCASII climb apparently for traffic below him and climbed into an aircraft above and to his right, converging. Small aircraft X, in my opinion, should also have been on air carrier Y's TCASII. This doesn't sound right. Supplemental information from acn 218061: air carrier Y descending for landing in limited visibility VFR conditions we were assigned 4000 ft. At approximately 4200 ft our TCASII registered an RA with a climb command. There was a VFR which we had just spotted when the TCASII registered another RA, this time to 'monitor vertical speed.' at this point, without us knowing it, we had lost IFR separation limits with small aircraft X above us. The controller turned us away from the traffic just after the RA. I feel the visibility caused visual identify of the targets to exceed ability of the human eye until the last moment. Fortunately the TCASII system saved our butts this day and I am extremely thankful we have the system installed in our aircraft. We rely on the TCASII on a daily basis.

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Original NASA ASRS Text

Title: ACR Y NON ADHERENCE TO ATC CLRNC UNAUTH CLB FROM ASSIGNED ALT RECEIVED TCASII RA CLB FROM VFR SMA HAD LTSS FROM SMA X. PLTDEV. EVASIVE ACTION TAKEN.

Narrative: EFP = E FEEDER RADAR, NFR = N FEEDER RADAR. I WAS WORKING EFR. SMA X WAS AT 5000 FT NEBOUND. NFR WAS WORKING ACR Y SWBOUND AT 4000 FT. ACR Y ADVISED HE WAS CLBING FOR TCASII (HE WAS OVER AN AREA WHERE FISH SPOTTER ACFT NORMALLY FLY AT LOW ALTS). THE NFR CTLR ADVISED ME OF ACR Y CLB AND I ISSUED A CLB TO SMA X AND THE REASON FOR CLB. SMA X ADVISED HE HAD ACR Y IN SIGHT AND WAS TOLD TO MAINTAIN VISUAL SEPARATION. SMA X LATER SAID THAT EVEN WITHOUT VISUAL SEPARATION THAT MY INSTRUCTIONS WOULD HAVE AVOIDED A PROB. I FEEL THAT EVEN WITHOUT MY INSTRUCTIONS THE ACFT WOULD HAVE MISSED, BUT NOT BY MUCH AND ON RADAR THE ACFT TARGETS WOULD HAVE TOUCHED. ACR Y REACTED TO A TCASII CLB APPARENTLY FOR TFC BELOW HIM AND CLBED INTO AN ACFT ABOVE AND TO HIS R, CONVERGING. SMA X, IN MY OPINION, SHOULD ALSO HAVE BEEN ON ACR Y'S TCASII. THIS DOESN'T SOUND RIGHT. SUPPLEMENTAL INFO FROM ACN 218061: ACR Y DSNDING FOR LNDG IN LIMITED VISIBILITY VFR CONDITIONS WE WERE ASSIGNED 4000 FT. AT APPROX 4200 FT OUR TCASII REGISTERED AN RA WITH A CLB COMMAND. THERE WAS A VFR WHICH WE HAD JUST SPOTTED WHEN THE TCASII REGISTERED ANOTHER RA, THIS TIME TO 'MONITOR VERT SPD.' AT THIS POINT, WITHOUT US KNOWING IT, WE HAD LOST IFR SEPARATION LIMITS WITH SMA X ABOVE US. THE CTLR TURNED US AWAY FROM THE TFC JUST AFTER THE RA. I FEEL THE VISIBILITY CAUSED VISUAL IDENT OF THE TARGETS TO EXCEED ABILITY OF THE HUMAN EYE UNTIL THE LAST MOMENT. FORTUNATELY THE TCASII SYS SAVED OUR BUTTS THIS DAY AND I AM EXTREMELY THANKFUL WE HAVE THE SYS INSTALLED IN OUR ACFT. WE RELY ON THE TCASII ON A DAILY BASIS.

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.