Narrative:

It was the first really clear day in several weeks, and a sat at that, so the skies of the area were very busy. I had called inbound to pao over the osi VOR and was told to hold for 5 mins. I was then cleared to proceed for left traffic runway 30, the normal approach from that direction. There was, needless to say, much traffic operating in the air traffic area, including the famous blimp positioning itself over stanford stadium. My route took me just to the northwest of the stadium. When I was about 2 mi from the airport, at 1500 ft, one of my passenger urgently called my attention to an small aircraft about to cross right to left right in front of, and slightly above us. I made a quick descending turn to the right, and the small aircraft appeared to react at the same time. I landed without further incident. None of my passenger remembered hearing the small aircraft on frequency, nor did I. The local controller told me later during my visit to the tower that she did remember clearing the small aircraft to transition at or above 2000 ft. Lesson #1: traffic is not necessarily where they are cleared to be. The more important lesson, however, is that pilots are always responsible to see and avoid, even when flying in airspace such as an air traffic area. The controllers are very good about calling traffic during normal times, but as things get busier than normal, their attention shifts progressively closer to the runway itself. Pilots need to be even more observant than usual during peak times. The presence of the blimp was even more unusual and called for extra caution as well.

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Original NASA ASRS Text

Title: PLT OF SMA GA ACFT DEVIATED FROM ASSIGNED ALT DURING ENTRY TO THE ARPT TFC PATTERN DUE TO A NMAC EVASIVE ACTION DSCNT.

Narrative: IT WAS THE FIRST REALLY CLR DAY IN SEVERAL WKS, AND A SAT AT THAT, SO THE SKIES OF THE AREA WERE VERY BUSY. I HAD CALLED INBOUND TO PAO OVER THE OSI VOR AND WAS TOLD TO HOLD FOR 5 MINS. I WAS THEN CLRED TO PROCEED FOR L TFC RWY 30, THE NORMAL APCH FROM THAT DIRECTION. THERE WAS, NEEDLESS TO SAY, MUCH TFC OPERATING IN THE ATA, INCLUDING THE FAMOUS BLIMP POSITIONING ITSELF OVER STANFORD STADIUM. MY RTE TOOK ME JUST TO THE NW OF THE STADIUM. WHEN I WAS ABOUT 2 MI FROM THE ARPT, AT 1500 FT, ONE OF MY PAX URGENTLY CALLED MY ATTN TO AN SMA ABOUT TO CROSS R TO L RIGHT IN FRONT OF, AND SLIGHTLY ABOVE US. I MADE A QUICK DSNDING TURN TO THE R, AND THE SMA APPEARED TO REACT AT THE SAME TIME. I LANDED WITHOUT FURTHER INCIDENT. NONE OF MY PAX REMEMBERED HEARING THE SMA ON FREQ, NOR DID I. THE LCL CTLR TOLD ME LATER DURING MY VISIT TO THE TWR THAT SHE DID REMEMBER CLRING THE SMA TO TRANSITION AT OR ABOVE 2000 FT. LESSON #1: TFC IS NOT NECESSARILY WHERE THEY ARE CLRED TO BE. THE MORE IMPORTANT LESSON, HOWEVER, IS THAT PLTS ARE ALWAYS RESPONSIBLE TO SEE AND AVOID, EVEN WHEN FLYING IN AIRSPACE SUCH AS AN ATA. THE CTLRS ARE VERY GOOD ABOUT CALLING TFC DURING NORMAL TIMES, BUT AS THINGS GET BUSIER THAN NORMAL, THEIR ATTN SHIFTS PROGRESSIVELY CLOSER TO THE RWY ITSELF. PLTS NEED TO BE EVEN MORE OBSERVANT THAN USUAL DURING PEAK TIMES. THE PRESENCE OF THE BLIMP WAS EVEN MORE UNUSUAL AND CALLED FOR EXTRA CAUTION AS WELL.

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.