Narrative:

I was nwbound just east of the san jose, ca, airport, descending from 5500 ft to 4500 ft, when the bay approach controller pointed out a P3 aircraft at my 10-11 O'clock position, about 2 mi, eastbound, climbing to 4000 ft. I saw the P3 (which probably just departed moffett field), reported it in sight, and was told to maintain visual separation, and continue my descent to 1500 ft. At that time the P3 was quite low, climbing slowly, and moving rapidly from my left toward my right. My initial assessment was that I would pass well behind the P3, so I began a rapid descent to 1500 ft preparatory to my landing at the hayward, ca, airport. I continued to scan the area for other traffic. When I saw the P3 next, it was rapidly becoming 12 O'clock position and co-altitude with my aircraft. This seemed to me to happen quite suddenly, and was totally unexpected based upon my initial impression that the P3 would pass well in front of and well below my flight path. In order to insure safe separation, I rolled into a left turn to pass behind the P3. The P3 crew saw me at this time, and rapidly transitioned from a climb to a descent to insure separation from me. The P3 told the controller that I had been 'close,' and the controller informed the P3 that I was maintaining visual separation. In retrospect, I should have remained at 4500 ft until the P3 was clear of my aircraft to the east. However I was rapidly approaching the segment of the sfo class B airspace which extends from 4000 ft to 8000 ft MSL. My initial impression that the P3 would pass well in front of, and below me, was based upon my first sight of the aircraft some distance away. As we came closer, the geometry of the situation proved me wrong. From my seat this was not obvious until the 2 aircraft were much closer than they should have been. It seems to me that the controller might have noted the conflict earlier than I did, and stopped my descent, or the P3's climb. I suspect the controller was busy, and was trying to expedite me. I was amazed at how little time I had to react once I decided that I must turn to avoid the P3. I have only come closer to other aircraft once or twice in 34 yrs of flying. I was very uncomfortable with the situation, and I am sure the P3 crew was not happy either. I usually avoid this area because of the heavy traffic. I will definitely avoid it in the future. I will not rely quite so much on busy controllers either.

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Original NASA ASRS Text

Title: PLT OF BE200 HAS CLOSE PROX WITH P3 WHEN USING VISUAL SEPARATION.

Narrative: I WAS NWBOUND JUST E OF THE SAN JOSE, CA, ARPT, DSNDING FROM 5500 FT TO 4500 FT, WHEN THE BAY APCH CTLR POINTED OUT A P3 ACFT AT MY 10-11 O'CLOCK POS, ABOUT 2 MI, EBOUND, CLBING TO 4000 FT. I SAW THE P3 (WHICH PROBABLY JUST DEPARTED MOFFETT FIELD), RPTED IT IN SIGHT, AND WAS TOLD TO MAINTAIN VISUAL SEPARATION, AND CONTINUE MY DSCNT TO 1500 FT. AT THAT TIME THE P3 WAS QUITE LOW, CLBING SLOWLY, AND MOVING RAPIDLY FROM MY L TOWARD MY R. MY INITIAL ASSESSMENT WAS THAT I WOULD PASS WELL BEHIND THE P3, SO I BEGAN A RAPID DSCNT TO 1500 FT PREPARATORY TO MY LNDG AT THE HAYWARD, CA, ARPT. I CONTINUED TO SCAN THE AREA FOR OTHER TFC. WHEN I SAW THE P3 NEXT, IT WAS RAPIDLY BECOMING 12 O'CLOCK POS AND CO-ALT WITH MY ACFT. THIS SEEMED TO ME TO HAPPEN QUITE SUDDENLY, AND WAS TOTALLY UNEXPECTED BASED UPON MY INITIAL IMPRESSION THAT THE P3 WOULD PASS WELL IN FRONT OF AND WELL BELOW MY FLT PATH. IN ORDER TO INSURE SAFE SEPARATION, I ROLLED INTO A L TURN TO PASS BEHIND THE P3. THE P3 CREW SAW ME AT THIS TIME, AND RAPIDLY TRANSITIONED FROM A CLB TO A DSCNT TO INSURE SEPARATION FROM ME. THE P3 TOLD THE CTLR THAT I HAD BEEN 'CLOSE,' AND THE CTLR INFORMED THE P3 THAT I WAS MAINTAINING VISUAL SEPARATION. IN RETROSPECT, I SHOULD HAVE REMAINED AT 4500 FT UNTIL THE P3 WAS CLR OF MY ACFT TO THE E. HOWEVER I WAS RAPIDLY APCHING THE SEGMENT OF THE SFO CLASS B AIRSPACE WHICH EXTENDS FROM 4000 FT TO 8000 FT MSL. MY INITIAL IMPRESSION THAT THE P3 WOULD PASS WELL IN FRONT OF, AND BELOW ME, WAS BASED UPON MY FIRST SIGHT OF THE ACFT SOME DISTANCE AWAY. AS WE CAME CLOSER, THE GEOMETRY OF THE SIT PROVED ME WRONG. FROM MY SEAT THIS WAS NOT OBVIOUS UNTIL THE 2 ACFT WERE MUCH CLOSER THAN THEY SHOULD HAVE BEEN. IT SEEMS TO ME THAT THE CTLR MIGHT HAVE NOTED THE CONFLICT EARLIER THAN I DID, AND STOPPED MY DSCNT, OR THE P3'S CLB. I SUSPECT THE CTLR WAS BUSY, AND WAS TRYING TO EXPEDITE ME. I WAS AMAZED AT HOW LITTLE TIME I HAD TO REACT ONCE I DECIDED THAT I MUST TURN TO AVOID THE P3. I HAVE ONLY COME CLOSER TO OTHER ACFT ONCE OR TWICE IN 34 YRS OF FLYING. I WAS VERY UNCOMFORTABLE WITH THE SIT, AND I AM SURE THE P3 CREW WAS NOT HAPPY EITHER. I USUALLY AVOID THIS AREA BECAUSE OF THE HVY TFC. I WILL DEFINITELY AVOID IT IN THE FUTURE. I WILL NOT RELY QUITE SO MUCH ON BUSY CTLRS EITHER.

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.