PA-24 PILOT HAS NEAR MISS WITH ACFT ON DOWNWIND IN VFR TFC PATTERN.

Narrative

ON FLT TO LABELLE MUNICIPAL ARPT; I ANNOUNCED ON 122.8 FOR 'LABELLE TFC' THAT I WAS 5 MI S AND LNDG ON RWY 32 AT LABELLE. THERE WERE 2-3 ACFT ANNOUNCING THEMSELVES IN THE PATTERN; AT LEAST TWO APPEARED TO BEING DOING TOUCH AND GOES. (THIS MUCH TFC AT LABELLE WAS NOT EXPECTED AND I THOUGHT UNUSUAL; AND I WANTED TO MAKE AS MANY ANNOUNCEMENTS AS POSSIBLE TO ALERT OTHERS THAT I WAS COMING INTO THE TFC AREA; SO I MADE THE '5 MI S' FIRST ANNOUNCEMENT.) I ANNOUNCED ALSO AGAIN AT 3 MI S. 1 ACFT ANNOUNCED SHE WAS LEAVING THE PATTERN. I THOUGHT I HAD HEARD WHAT I BELIEVED TO BE THE ONLY ACFT A FACTOR IN MY FLT PATH HAD ANNOUNCED THEY WERE ON BASE. I ANNOUNCED AGAIN AT '2 MI W' (READING FROM LORAN READOUT) AS I WAS PREPARING TO ENTER PATTERN FOR RWY 32; MY HDG APPROX NW AT THIS TIME. ABOUT 30 SECONDS LATER SAW A SINGLE ENG ACFT AHEAD ABOUT 150 FT HIGHER PASSING ABOUT 500 FT TO MY R (E OF ME) DOING AN APPARENT VERY WIDE DOWNWIND LEG FOR WHICH I BELIEVE THAT SAME ACFT THEN ANNOUNCED A TURN TO BASE. I THEN IMMEDIATELY ANNOUNCED I WAS 1.5 MI W (READING FROM LORAN READOUT) AND WAS ENTERING PATTERN AND FOLLOWING ACFT ON BASE. I MADE A R TURN AND ENTERED THE DOWNWIND FOR RWY 32. CONTRIBUTING FACTORS WERE NUMEROUS ACFT IN PATTERN AT UNCTLED FIELD; POSSIBLY TRAINING ACFT; AND AT LEAST 1 ACFT MAKING A WIDE PATTERN WHICH I DID NOT EXPECT. THERE WAS A FAIRLY STRONG L XWIND OF POSSIBLY 10-15 KTS WITH GUSTS AT AN UNKNOWN SPD WHICH MAY HAVE CONTRIBUTED AS A DISTR. HUMAN PERFORMANCE CONSIDERATIONS: MUST BE MORE AWARE OF ALL THE ACFT POS IN THE PATTERN AND BE EXPECTING THAT SOME MAY BE OUTSIDE THE NORMAL PATTERN BOUNDARIES. WHEN MORE THAN 1 ACFT IN PATTERN; PERHAPS MORE ANNOUNCEMENTS SHOULD BE MADE OF POS; AND/OR WHEN 'TFC IN SIGHT.'