ACR X TCASII RA WITH VFR SMA NEAR CLASS B AIRSPACE.

Narrative

ACR X CONDUCTING A VISUAL APCH TO RWY 26R AT PHX; WE RECEIVED A TCASII RA. WE SAW THE SMA VISUALLY; AND PASSED ABOVE AND IN FRONT WITH CLOSE; BUT ADEQUATE; SEPARATION. WE WERE EXTREMELY BUSY TRYING TO KEEP PROPER SEPARATION FROM THE TFC IN FRONT OF US; CONFIGURING AND SLOWING THE ACFT; AND LOOKING FOR THE OTHER TFC. WE RECEIVED A TWR TA AT ABOUT THE SAME TIME WE ACQUIRED THE CONFLICTING TFC. THE TWR ADVISED ME LATER THAT THIS IS A COMMON OCCURRENCE AT THIS ARPT WITH ACFT FLYING VFR AT 1500 FT AGL ON THE EDGE OF THE CLASS 'B' AIRSPACE. IN MY OPINION; THIS IS NOT A GOOD SIT FOR EITHER ACFT. WE WERE ON THE GS FOR THE APCH. I THINK MORE VERT SEPARATION IS IN ORDER FOR THAT AREA OF THE APCH; PERHAPS WIDENING THE CLASS 'B' AIRSPACE. SINCE IT SEEMS TO BE COMMON PRACTICE FOR VFR PLTS TO FLY ALONG A ROAD MARKING THE CLASS 'B' BOUNDARY AT PHX; PLTS CONDUCTING ILS APCHS; VISUAL OR IMC; SHOULD BE WARNED ABOUT THIS POSSIBLE CONFLICT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATED THE ACFT INVOLVED WAS A SE CESSNA. HE DID NOT RESPOND TO TCASII RA BECAUSE HE HAD THE ACFT IN SIGHT. RPTR WAS INFORMED THAT FOLLOWING THE GS ON THE APCH AT PHX WILL DROP THE ACFT OUT THE FLOOR OF THE CLASS B AIRSPACE.