Narrative:

During descent for landing, we were on a heading of 280 degrees to intercept the sjc 30L localizer. We were to maintain 5000' or above until 16 DME. At approximately 5200' and 16.7 DME I saw a single engine high wing small aircraft Y aircraft at approximately 5000-5500' heading sse. I continued my descent and initiated a 25-45 degree left bank, descending to approximately 4600' in order to miss him. We queried approach and they said they had no one on radar. We told them of the conflict and the reason for missing our crossing altitude assignment. We continued the approach and landing west/O further incident. If we would not have initiated our descending left turning evasive maneuver, there very well could have been a midair collision. I don't believe air carrier's should be vectored (as we were) into that area, since that is a favorite transit area for small aircraft who want to avoid the TCA/arsa airspace.

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Original NASA ASRS Text

Title: ACR MLG X ON VECTORS TO APCH AT SJC HAS NMAC WITH UNIDENTIFIED SMA Y.

Narrative: DURING DSNT FOR LNDG, WE WERE ON A HDG OF 280 DEGS TO INTERCEPT THE SJC 30L LOC. WE WERE TO MAINTAIN 5000' OR ABOVE UNTIL 16 DME. AT APPROX 5200' AND 16.7 DME I SAW A SINGLE ENG HIGH WING SMA Y ACFT AT APPROX 5000-5500' HDG SSE. I CONTINUED MY DSNT AND INITIATED A 25-45 DEG LEFT BANK, DSNDING TO APPROX 4600' IN ORDER TO MISS HIM. WE QUERIED APCH AND THEY SAID THEY HAD NO ONE ON RADAR. WE TOLD THEM OF THE CONFLICT AND THE REASON FOR MISSING OUR XING ALT ASSIGNMENT. WE CONTINUED THE APCH AND LNDG W/O FURTHER INCIDENT. IF WE WOULD NOT HAVE INITIATED OUR DSNDING LEFT TURNING EVASIVE MANEUVER, THERE VERY WELL COULD HAVE BEEN A MIDAIR COLLISION. I DON'T BELIEVE ACR'S SHOULD BE VECTORED (AS WE WERE) INTO THAT AREA, SINCE THAT IS A FAVORITE TRANSIT AREA FOR SMA WHO WANT TO AVOID THE TCA/ARSA AIRSPACE.

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.