MEM APCH CTLR DESCRIBED CONFLICT EVENT AT 8500 BETWEEN VFR AND MEM ARR CITING LATE ISSUANCE OF TFC AND LISTING EQUIP ANOMALIES AS CONTRIBUTORY.

Narrative

I WAS WORKING W ARR. ACFT X CHKED IN ON MY FREQ ON THE GQE 3 ARR AT 10000 FT. I ISSUED ACFT X A 110 DEG HDG AND DSNDED THEM TO 6000 FT FOR RWY 18R ILS APCH. AS ACFT X WAS PASSING GQE; I NOTICED THE COLLISION ALERT GOING OFF. I LOOKED AND THERE WAS TFC FOR ACFT X AT HIS 10 O'CLOCK POS AND 2 MI AT 8500 FT. I ISSUED THE TFC AND A TURN TO A 180 DEG HDG IF THEY WANTED. ACFT X REPLIED THAT THEY WERE CLBING FOR AN RA FROM THEIR TCAS. BY THIS TIME; I ADVISED ACFT X THAT THEY WERE CLR OF THE TFC AND WHEN THEY FELT READY; THEY COULD DSND BACK TO 6000 FT. A COMPANY ACFT IN TRAIL OF ACFT X RPTED THAT THE ACFT APPEARED TO BE A LOW WING; SINGLE ENG ACFT AND THE INDICATED ALT APPEARED CLOSE TO CORRECT. I BELIEVE THERE WERE SEVERAL REASONS WHY I WAS LATE ISSUING A TFC CALL. FIRST; WE WERE IN BTWN PUSHES WITH LIGHT TFC; THEREFORE; MY SCAN WAS LULLED SOMEWHAT. SECOND; AT THE W ARR POS; THERE IS GLARE FROM A WALL OF MONITORS BEHIND THE POS THAT CAN MAKE IT DIFFICULT TO SEE. FINALLY; MEM HAS STARS WHICH ALLOWS FOR DIFFERENT COLORS FOR DIFFERENT PRIORITIES OF DATA TAGS. UNIDENTED VFR TAGS ARE GREEN AND IDENTED VFR TAGS AND IFR TAGS ASSOCIATED WITH THE POS I AM WORKING ARE WHITE AND POINTS ARE AMBER. THE UNIDENTED VFR TAG WAS GREEN; AND CTLRS HAVE A TENDENCY TO PUT GREEN TAGS OUT OF THEIR FOCUS OF ATTN. THE COLLISION ALERT WORKED PERFECTLY IN THIS INSTANCE (IT IS NOTORIOUS FOR GOING OFF AFTER ACFT HAVE PASSED); SO I WAS ABLE TO GIVE A TIMELY TFC ALERT.