Narrative:

Crossing over the field in small aircraft X, I was given frequency change to other tower frequency. I was concerned about getting on frequency with frequency congestion, and wanted to turn on course. Was not watching, and apparently neither was the pilot of small aircraft Y. Afterward I made some non-committal reply to the tower, and they apparently were unaware of any incident. ATC never assigned me an altitude. Callback conversation with reporter revealed the following: reporter explained geometry of the occurrence. Small aircraft X was transiting sjc arsa east to west, perpendicular to the runway with intention to turn northerly after crossing the runways. Aircraft Y was on left downwind for sjc runway 29 but was well above pattern altitude. Closure angle was X's 2 O'clock. Y never saw X. X sighted Y too late for evasive action. Reporter later contacted sjc tower by phone and learned that they were aware of the occurrence, but were having some sort of intracoord problem at the time and were not in radio contact with either aircraft at the time of the near midair collision.

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Original NASA ASRS Text

Title: SMA, TRANSITING SJC ARSA WITH ATC PERMISSION, HAS NMAC WITH SMA ON HIGH DOWNWIND FOR SJC RWY 29.

Narrative: XING OVER THE FIELD IN SMA X, I WAS GIVEN FREQ CHANGE TO OTHER TWR FREQ. I WAS CONCERNED ABOUT GETTING ON FREQ WITH FREQ CONGESTION, AND WANTED TO TURN ON COURSE. WAS NOT WATCHING, AND APPARENTLY NEITHER WAS THE PLT OF SMA Y. AFTERWARD I MADE SOME NON-COMMITTAL REPLY TO THE TWR, AND THEY APPARENTLY WERE UNAWARE OF ANY INCIDENT. ATC NEVER ASSIGNED ME AN ALT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING: RPTR EXPLAINED GEOMETRY OF THE OCCURRENCE. SMA X WAS TRANSITING SJC ARSA E TO W, PERPENDICULAR TO THE RWY WITH INTENTION TO TURN NORTHERLY AFTER XING THE RWYS. ACFT Y WAS ON LEFT DOWNWIND FOR SJC RWY 29 BUT WAS WELL ABOVE PATTERN ALT. CLOSURE ANGLE WAS X'S 2 O'CLOCK. Y NEVER SAW X. X SIGHTED Y TOO LATE FOR EVASIVE ACTION. RPTR LATER CONTACTED SJC TWR BY PHONE AND LEARNED THAT THEY WERE AWARE OF THE OCCURRENCE, BUT WERE HAVING SOME SORT OF INTRACOORD PROB AT THE TIME AND WERE NOT IN RADIO CONTACT WITH EITHER ACFT AT THE TIME OF THE NMAC.

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.