AN MD80 RECEIVED A TCASII RA FROM A VFR TFC WATCH C172 WHILE ON VECTOR FOR A VISUAL APCH. ATC EXCHANGED TFC. GA PLT RPTED THE MD80 IN SIGHT. THE MD80 FLC DID NOT OBSERVE C172 AND UPON LNDG; FILED A NMAC RPT.

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I DEPARTED TUS ON A VFR FLT TO CONDUCT THE AFTERNOON TFC WATCH ON DEC/XX/97. WHILE CLBING I WAS ADVISED OF TFC; ACR Y. HAVING THE TFC IN SIGHT I ADVISED ATC. I WAS GIVEN A HDG OF 300 DEGS AND CONTINUED MY CLB. AS I WAS APCHING MY LEVELOFF ALT OF 6500 FT THE TFC WAS GIVEN A HEADING TOWARDS THE ARPT AND I WAS GIVEN A HDG OF 330 DEGS. I LEVELED OFF AT 6500 FT AND CONFIGURED THE ACFT FOR CRUISE FLT. WHILE I WAS PERFORMING THESE TASKS I HEARD THE TFC ADVISE ATC THEIR TCASII WAS 'WHINING AT THEM' AND THAT THEY SHOWED TFC AT THEIR SAME ALT. WITH MY NEW HEADING WE WERE ON CONVERGING FLT PATHS; BUT SEPARATED BY 500 FT. I TURNED BACK TO MY HDG OF 300 DEGS; WHICH KEPT ME CLEARLY OUT OF THE WAY OF THE TFC. AT NO TIME DID I FEEL THE SIT WAS A DANGER. THE CTLR WAS ATTENTIVE TO THE SIT. ALTHOUGH I HAD THE TFC IN SIGHT AND MAINTAINED VFR FLT RULES TO SEE AND AVOID; A HEADING THAT WOULD HAVE TAKEN ME FURTHER FROM THE ARRIVING ACFT WOULD HAVE ELIMINATED ANY CONFUSION. SUPPLEMENTAL INFO FROM ACN 387997: CESSNA (ACFT X) WAS ON L DOWNWIND DEP FROM TUCSON INTL FROM RWY 11L FOR HIS TFC WATCH ORBIT CLBING TO 6500 FT. ACR Y (MD82) WAS ON A VECTOR TO BASE FOR RWY 11L DSNDING TO 7000 FT. TFC WAS EXCHANGED. CESSNA HAD ACR Y IN SIGHT AND WAS JUST LEVELING AT 6500 FT. THE MD82 DID NOT HAVE CESSNA IN SIGHT. AS THE MD82 PASSED ABOVE CESSNA THE ACR PLT RPTED THEY WERE CLBING IN RESPONSE TO TCASII ADVISORY. ABOUT 20 MINS AFTER LNDG THE MD82 PLT CALLED TO RPT AN NMAC. THE PLT BASES THE NEAR MIDAIR RPT ONLY UPON INFO FROM THE TCASII; NO VISUAL REF. ALTHOUGH FROM THE RADAR DATA EXTRACTION THERE WAS A POINT WHEN RADAR SHOWED CESSNA AT 6600 FT AND ALSO A POINT WHERE MD82 WAS AT 6900 FT. VERT SEPARATION OF 500 FT BTWN IFR AND VFR ACFT IS STANDARD OPERATING PRACTICE ALONG WITH AN EXCHANGE OF TFC IN CLASS C AIRSPACE; BUT APPARENTLY NOT WHEN TCASII IS INVOLVED. SUPPLEMENTAL INFO FROM ACN 388244: I WAS THE PF. WE RECEIVED A TA 10 NM N OF TUS AT 7000 FT MSL; 180 KTS; WHILE ON VECTORS TO RWY 11L. 5 SECONDS LATER WE GOT AN RA TO MONITOR VERT SPD ONCE; THEN A CLB; CLB WARNING; COMMANDING A 1500 FPM CLB. RESPONDED IMMEDIATELY WITH A CLB. ADVISED APCH WE WERE RESPONDING TO AN RA. ACFT INDICATED 300 FT DIRECTLY BELOW US AT THE CLOSEST POINT. THEN HEARD CLR OF CONFLICT. WE NEVER SAW THE TFC. WE THEN ACCEPTED A VISUAL TO RWY 11L. SHORTLY THEREAFTER; WE INFORMED TWR WE WERE TOO HIGH TO LAND. WE WERE GIVEN VECTORS FOR ANOTHER APCH AND LNDG RWY 11L.