Narrative:

I was crosswind turning downwind and when I rolled out, the other aircraft was just ahead of me and a little below me also downwind. I had not seen this aircraft as I flew upwind and crosswind prior to my turn downwind. An additional aircraft had just taken off and another was also entering downwind behind me. I was aware of those other 2 aircraft from their calls on unicom. The aircraft I nearly collided with either had not made any calls or had transmitted the same time as others and was covered up. -- Most likely had made no calls -- I was looking for additional aircraft but I was also distracted by the 2 aircraft I knew of. I had been listening to unicom for about 6 mins after being advised to change frequencys by ATC. Lessons: 1) do not be distracted by airplanes that you know of -- there might be another you don't know of. 2) be sure to make calls during landing process -- upwind -- crosswind -- downwind -- base -- final etc. If aircraft had been calling, I would have been able to find it before I nearly rolled out on top of it.

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Original NASA ASRS Text

Title: AN SMA PLT HAD AN NMAC IN THE TFC PATTERN AT AN UNCTLED ARPT.

Narrative: I WAS XWIND TURNING DOWNWIND AND WHEN I ROLLED OUT, THE OTHER ACFT WAS JUST AHEAD OF ME AND A LITTLE BELOW ME ALSO DOWNWIND. I HAD NOT SEEN THIS ACFT AS I FLEW UPWIND AND XWIND PRIOR TO MY TURN DOWNWIND. AN ADDITIONAL ACFT HAD JUST TAKEN OFF AND ANOTHER WAS ALSO ENTERING DOWNWIND BEHIND ME. I WAS AWARE OF THOSE OTHER 2 ACFT FROM THEIR CALLS ON UNICOM. THE ACFT I NEARLY COLLIDED WITH EITHER HAD NOT MADE ANY CALLS OR HAD XMITTED THE SAME TIME AS OTHERS AND WAS COVERED UP. -- MOST LIKELY HAD MADE NO CALLS -- I WAS LOOKING FOR ADDITIONAL ACFT BUT I WAS ALSO DISTRACTED BY THE 2 ACFT I KNEW OF. I HAD BEEN LISTENING TO UNICOM FOR ABOUT 6 MINS AFTER BEING ADVISED TO CHANGE FREQS BY ATC. LESSONS: 1) DO NOT BE DISTRACTED BY AIRPLANES THAT YOU KNOW OF -- THERE MIGHT BE ANOTHER YOU DON'T KNOW OF. 2) BE SURE TO MAKE CALLS DURING LNDG PROCESS -- UPWIND -- XWIND -- DOWNWIND -- BASE -- FINAL ETC. IF ACFT HAD BEEN CALLING, I WOULD HAVE BEEN ABLE TO FIND IT BEFORE I NEARLY ROLLED OUT ON TOP OF IT.

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.