CLOSE PROX ACR-MLG GA-SMA S OF SJC.

Narrative

ONCE AGAIN I HAVE HAD A TCASII INCIDENT WHILE APCHING SJC IN CALIFORNIA. WHILE ON AN EXTENDED L BASE APPROX 10 MI S OF SJC IN DAY VFR; ON A VISUAL APCH TO 30L; WE WERE GIVEN A TA BY ATC BUT DID NOT SPOT THE TFC. 30 SECONDS TO 1 MIN LATER OUR TCASII SYS GIVES US A TA FOLLOWED VERY SHORTLY BY AN RA. IN THIS CASE TELLING US TO REDUCE DSCNT; WHICH WE ARE REQUIRED BY REG TO RESPOND TO. MOMENTS LATER WE SPOTTED THE SMA PASSING 700 FT DIRECTLY BENEATH US TRAVELING S. WITHOUT TCASII WE WOULD HAVE HAD A VERY NEAR MISS OR POSSIBLE COLLISION. MY CONCERN IS THAT OF THE 4 RA'S I HAVE ENCOUNTERED IN THE PAST YR; 3 OF THEM HAVE OCCURRED WHILE APCHING SJC UNDER VERY SIMILAR CIRCUMSTANCES. KEEP IN MIND AN RA REQUIRES THE CREW TO DEVIATE; A CLB OR DSCNT; FROM A FLT PATH. IN EVERY CASE ATC ISSUED A TA; WE DID NOT SPOT THE TFC; HEARD NOTHING MORE FROM ATC; THEN MOMENTS LATER HAD A TCASII RA REQUIRING A DEV AVERTING A NEAR MISS OR POSSIBLE COLLISION. EVEN WHEN ATC IS CTLING THE OTHER TFC WE FREQUENTLY ARE UNABLE TO ACQUIRE VISUAL CONTACT WITH THE OTHER ACFT. I FEEL THAT ATC RELIES FAR TOO HEAVILY ON VISUAL CONTACT FOR SEPARATION IN SJC. THIS IS MORE THAN JUST A BUSY AREA. I FEEL IT IS ATC'S INABILITY TO ADEQUATELY SEPARATE IFR AND VFR TFC. WE SHOULD NOT HAVE TO RELY ON TCASII FOR BASIC ATC SEPARATION. I WRITE THIS IN THE HOPES SOMEONE WILL COMPILE DATA ON THE NUMBERS OF TCASII INCIDENTS IN SJC. I HAVE NOT ENCOUNTERED THIS MUCH OF A PROBLEM ANYWHERE ELSE IN THE COUNTRY. I HOPE THAT IN THE FUTURE BETTER ATC SEPARATION CAN BE PROVIDED.