Narrative:

We were descending on the big sur arrival to sfo. As we approached anjee intersection at approximately 17000 ft, ZOA advised us of VFR traffic, an air carrier turboprop, opposite direction at 15500 ft. We saw the traffic on our TCASII display on the ehsi, but at no time did we make visual contact with the traffic. ZOA advised us that the traffic had us in sight. This was the only advisory ZOA gave us. It was clear to us from the TCASII display that there was going to be a conflict. Sure enough, as we descended through 16000 ft, we got an RA and a command to climb. We climbed back to 16500 and the traffic passed beneath us, although we never saw it. We advised ZOA, but got no response. If it had not been for TCASII, we may well have collided. Suggestion: it is not enough, in such a situation, for only 1 aircraft to have the other in sight. Both aircraft should have reported each other in sight, or ATC should have vectored us (the IFR traffic) around the VFR traffic.

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Original NASA ASRS Text

Title: ACR DSNDING AS CLRED HAS TCASII RA TO CLB.

Narrative: WE WERE DSNDING ON THE BIG SUR ARR TO SFO. AS WE APCHED ANJEE INTXN AT APPROX 17000 FT, ZOA ADVISED US OF VFR TFC, AN ACR TURBOPROP, OPPOSITE DIRECTION AT 15500 FT. WE SAW THE TFC ON OUR TCASII DISPLAY ON THE EHSI, BUT AT NO TIME DID WE MAKE VISUAL CONTACT WITH THE TFC. ZOA ADVISED US THAT THE TFC HAD US IN SIGHT. THIS WAS THE ONLY ADVISORY ZOA GAVE US. IT WAS CLR TO US FROM THE TCASII DISPLAY THAT THERE WAS GOING TO BE A CONFLICT. SURE ENOUGH, AS WE DSNDED THROUGH 16000 FT, WE GOT AN RA AND A COMMAND TO CLB. WE CLBED BACK TO 16500 AND THE TFC PASSED BENEATH US, ALTHOUGH WE NEVER SAW IT. WE ADVISED ZOA, BUT GOT NO RESPONSE. IF IT HAD NOT BEEN FOR TCASII, WE MAY WELL HAVE COLLIDED. SUGGESTION: IT IS NOT ENOUGH, IN SUCH A SIT, FOR ONLY 1 ACFT TO HAVE THE OTHER IN SIGHT. BOTH ACFT SHOULD HAVE RPTED EACH OTHER IN SIGHT, OR ATC SHOULD HAVE VECTORED US (THE IFR TFC) AROUND THE VFR TFC.

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.