Narrative:

Pao and nuq are approximately 3 NM apart. Pao was using runway 30 and nuq was using runways 14L and right. Pao tower repeatedly announced that nuq had mlt traffic in closed patterns, right traffic for runway 14R. Pao had numerous departures and arrs, plus approximately 9 light aircraft in closed traffic. I was on right downwind, nearly halfway to nuq. Pao tower told me to follow small aircraft Y on right base. However, I was following small aircraft Z and 1/4 mi ahead of me on right base. I informed the tower that I was following small aircraft Z. Tower told me that there was no aircraft ahead of me on downwind. The pilot of the small aircraft Z called local and said that she was ahead of me on downwind, and was turning base. Halfway through the base turn the small aircraft Z descended rapidly approximately 200'. I told my student to turn base. Just after he began rolling into the turn, we saw the mlt a pass over and to the left of small aircraft Z, and pass ahead of us. Mlt a was in his base turn at the time. I declined the pao local controller's instruction to follow small aircraft Y on base because I did not want to cause a collision hazard by cutting off the small aircraft Z. However, by doing so, I caused enough confusion on the frequency and to the controller that both my aircraft and small aircraft Z flew into the adjacent nuq pattern.

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Original NASA ASRS Text

Title: NMAC BETWEEN SMA X IN TRAFFIC PATTERN AT PAO AND MLT A IN CONFLICTING TRAFFIC PATTERN AT NUQ.

Narrative: PAO AND NUQ ARE APPROX 3 NM APART. PAO WAS USING RWY 30 AND NUQ WAS USING RWYS 14L AND R. PAO TWR REPEATEDLY ANNOUNCED THAT NUQ HAD MLT TFC IN CLOSED PATTERNS, RIGHT TFC FOR RWY 14R. PAO HAD NUMEROUS DEPS AND ARRS, PLUS APPROX 9 LIGHT ACFT IN CLOSED TFC. I WAS ON RIGHT DOWNWIND, NEARLY HALFWAY TO NUQ. PAO TWR TOLD ME TO FOLLOW SMA Y ON RIGHT BASE. HOWEVER, I WAS FOLLOWING SMA Z AND 1/4 MI AHEAD OF ME ON RIGHT BASE. I INFORMED THE TWR THAT I WAS FOLLOWING SMA Z. TWR TOLD ME THAT THERE WAS NO ACFT AHEAD OF ME ON DOWNWIND. THE PLT OF THE SMA Z CALLED LCL AND SAID THAT SHE WAS AHEAD OF ME ON DOWNWIND, AND WAS TURNING BASE. HALFWAY THROUGH THE BASE TURN THE SMA Z DSNDED RAPIDLY APPROX 200'. I TOLD MY STUDENT TO TURN BASE. JUST AFTER HE BEGAN ROLLING INTO THE TURN, WE SAW THE MLT A PASS OVER AND TO THE LEFT OF SMA Z, AND PASS AHEAD OF US. MLT A WAS IN HIS BASE TURN AT THE TIME. I DECLINED THE PAO LCL CTLR'S INSTRUCTION TO FOLLOW SMA Y ON BASE BECAUSE I DID NOT WANT TO CAUSE A COLLISION HAZARD BY CUTTING OFF THE SMA Z. HOWEVER, BY DOING SO, I CAUSED ENOUGH CONFUSION ON THE FREQ AND TO THE CTLR THAT BOTH MY ACFT AND SMA Z FLEW INTO THE ADJACENT NUQ PATTERN.

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.