NMAC. AT UNCTLED ARPT; RPTR PLT LANDED OVER THE TOP OF ANOTHER ACFT ON SHORT FINAL AND NEVER DID SEE IT. NON TWR ARPT UNICOM.

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I WAS PILOTING A PA28-151/A ON A FILED VFR FLT PLAN FROM BFF TO 1V5. I WAS UTILIZING FLT FOLLOWING BY DENVER CTL AND HAD BEEN MONITORING THE BOULDER CTAF FREQ FOR ABOUT 5 MINS TO FAMILIARIZE MYSELF WITH CURRENT LCL TFC. RADAR SVC WAS TERMINATED BY DENVER CTL; AND I THEN BROADCAST ON BOULDER'S CTAF FREQ. I STATED; 'BOULDER TFC; CHEROKEE IS 5 MI TO THE NE. I'LL BE ENTERING A L DOWNWIND FOR ZERO- EIGHT; ANY TFC IN THE AREA; PLEASE ADVISE.' THERE WAS NO REPLY TO THIS INQUIRY. I WAS THEN PREPARING TO MAKE A 45 DEG ENTRY TO A L DOWNWIND APCH AT 1000 FT AGL. TFC WAS A RED AND WHITE CESSNA IN VIEW ABOUT 2 NM AHEAD WHICH RPTED DOWNWIND AT THAT TIME AND WAS APPROX 700 FT AGL. I ALSO MADE ANOTHER POS RPT AT THAT TIME; AND WAS BTWN 2 AND 3 NM NE OF THE ARPT VISUALLY AND BY GPS. THE TFC AHEAD APPEARED TO BE MID-FIELD. I FLEW A STANDARD L-HAND PATTERN. BEING UNFAMILIAR WITH THE AREA AND MINDFUL OF LCL NOISE ABATEMENT PROCS. I SCANNED THE GND TO ORIENT MYSELF. WHEN I LOOKED AHEAD; TFC WAS NO LONGER IN VIEW. I CONTINUED TO ACTIVELY SCAN FOR THE TFC; AND RPTED MID- FIELD L DOWNWIND; TURN TO L BASE AND TURN TO FINAL. TFC WAS NOT IN SIGHT AT ANY POINT. ON TURNING FINAL; THE ENTIRE RWY WAS IN VIEW AND THERE WAS NO TFC ON THE ACTIVE. THE TFC AHEAD DID NOT XMIT POS AFTER RPTING DOWNWIND. THE REASON I SPECIFICALLY RPTED EACH LEG OF MY APCH; DESPITE TYING UP THE CTAF/UNICOM FREQ; WAS THAT I DID NOT HAVE THE TFC IN SIGHT. I FLEW A 1000 FT AGL PATTERN WITH A 500 FPM RATE OF DSCNT FROM 1000 FT SHORT OF THE RWY END. MY APCH SPD WAS 85 MPH. WHAT I DID TO AVOID TFC WAS RPT EACH LEG OF MY APCH. WHAT I DID NOT DO THAT COULD HAVE BEEN HELPFUL WAS SPECIFICALLY REQUEST THE TFC AHEAD TO RPT ITS POS WHEN I NO LONGER HAD IT IN SIGHT. I DID NOT PERFORM A GAR FOR 2 REASONS. ONE; THE TFC AHEAD DID NOT RPT A POS IN THE PATTERN THAT WOULD HAVE SUGGESTED A CONFLICT. TWO; WHILE I WAS ON DOWNWIND; ABOUT TO TURN BASE; OTHER TFC SELF-RPTED APCH FROM THE SE; WITH INTENT TO ENTER MID-FIELD FOR A L DOWNWIND APCH. AGAR AT THAT POINT WOULD HAVE REQUIRED MANEUVERING TO AVOID A POTENTIAL COLLISION HAZARD WITH THIS IN-COMING TFC. THIS WOULD HAVE PLACED MY ACFT BELOW 1000 FT AGL OVER A RESIDENTIAL AREA AT A TIME I DID NOT HAVE REASON TO BELIEVE THE TFC AHEAD WAS A HAZARD. BECAUSE NO ACFT WERE ON THE ACTIVE; OR VISIBLE ALOFT DURING MY FINAL APCH AND THERE WERE NO REMARKS FROM TFC IN RESPONSE TO MY POS RPTS; I SUPPOSED THE TFC AHEAD WAS ALREADY CLR OF THE ACTIVE AND TAXIING. BECAUSE THE GA RAMP IS ADJACENT TO THE RWY IN BOULDER; IT WOULD NOT HAVE BEEN POSSIBLE TO LOCATE THE TFC ON THE GND; ALTHOUGH I LOOKED. I LANDED NORMALLY AND AFTERWARDS WAS INFORMED BY GND PERSONNEL I HAD 'LANDED RIGHT OVER' THE CESSNA TFC AHEAD. GND PERSONNEL ESTIMATED THERE MAY HAVE BEEN AS LITTLE AS 150 FT VERT SEPARATION BTWN ACFT. GND PERSONNEL ALSO INDICATED THE PLT OF THE OTHER ACFT WAS A STUDENT PLT. I DO NOT KNOW WHY HE MADE ONLY THE SINGLE DOWNWIND POS RPT; AND FAILED TO RESPOND WHEN I RPTED BEING ON THE SAME LEG OF THE LNDG APCH AS HE (AS WE MUST HAVE BEEN; AT LEAST ON FINAL). I ALSO DO NOT KNOW ANY PARTICULARS OF THE STUDENT'S TRAINING; LOG-TIME OR THE LIKE. NATURALLY; I HAVE SOME CONCERNS WHETHER THE STUDENT KNEW THE NAMES OF THE VARIOUS LEGS OF AN APCH AT THE TIME HE MADE THIS FLT. I IMAGINE HE IS QUITE FAMILIAR WITH THEM NOW. THIS WOULD BE A POSSIBLE EXPLANATION FOR THE FAILURE TO RPT POS; OR TO RPT THE CONFLICT WITH MY POS. CLRLY; A CONTRIBUTING FACTOR WAS THE STUDENT PLT'S FLYING A LOWER-THAN-NORMAL APCH. THE FACT MY ACFT WAS A LONG-WING; AND HIS A HIGH- WING AGGRAVATED THE SIT. THE FARS STATE THAT THE PLT OF THE OTHER ACFT HAD THE RIGHT-OF-WAY BY VIRTUE OF BEING LOWER IN THE PATTERN. CERTAINLY I WOULD HAVE ALTERED MY OWN APCH HAD I ANY INDICATION TFC WAS BELOW ME AND A POTENTIAL HAZARD DUE TO PROX. THE MOST IMPORTANT FACT IN ANY MIDAIR COLLISION IS THAT BOTH PLTS ARE EQUALLY DEAD AFTERWARDS; WHETHER THEY WERE AT FAULT OR NOT. AT RELATIVELY HIGH TFC; UNCTLED ARPTS SUCH AS BOULDER; THE ONLY SEPARATION OF ACFT IS BY PLT VIGILANCE AND SELF-RPT OF POS. I SEE MY OWN FAILURE IN THIS SIT TO HAVE BEEN FAILING TO SPECIFICALLY ASK THE OTHER PLT'S POS; AND INITIATE A GAR HAD THERE BEEN NO REPLY. BECAUSE OF THE LOW PATTERN FLOWN BY THE OTHER ACFT; VISUAL CONTACT WAS NOT POSSIBLE. I PLACE A HIGH PRIORITY TO BETTERING MYSELF AS A PLT. I WAS GOING TO BOULDER TO TAKE THE INST-RATING; AIRPLANE PLT KNOWLEDGE TEST; WHICH I PASSED DESPITE MY CONSIDERABLE DISTR AT THE TIME. I PLAN IFR FLT-TRAINING AUG XA TO XI. I AM ALSO SCHEDULED TO DO A SMALL AMOUNT OF AEROBATIC TRAINING. BECAUSE I FLY A SMALL FIXED-GEAR; NORMAL CATEGORY ACFT; I WILL FIND LITTLE ACTUAL APPLICATION FOR IFR FLT; AND NONE FOR AEROBATIC FLT. I AM PURSUING THESE IN ORDER TO BECOME A BETTER AND SAFER PLT. SHOULD YOU HAVE ANY OTHER PARTICULAR AREA YOU WOULD RECOMMEND I WORK TO BECOME MORE PROFICIENT IN; I WOULD GREATLY VALUE YOUR INPUT. POSSIBLE ADMINISTRATIVE OR REGULATORY SOLUTIONS TO SUCH SITS; ANY ONE OF WHICH WOULD HAVE AVERTED THIS NEAR-COLLISION: REQUIRE PLTS TO MAINTAIN CONTINUOUS VISUAL CONTACT WITH ANY TFC AHEAD IN THE PATTERN. REQUIRE PLTS TO MAKE A VISUAL CONTACT WITH ANY TFC THAT PRECEDED THEM IN THE PATTERN PRIOR TO LNDG; WHETHER THE TFC REMAINS ALOFT; OR IS ON THE GND. REQUIRE A SPECIFIED DISTANCE BTWN THE GA RAMP AND RWYS AT UNCTLED ARPTS. REVIEW STUDENT PLT TRAINING PROCS AT BOULDER. SUSPEND STUDENT SOLO FLTS AT BOULDER. CHANGE BOULDER'S AIRSPACE CLASSIFICATION. REQUIRE RESPONDING TO POS INQUIRIES BY OTHER ACFT WHEN IN THE AREA OF AN ARPT. REQUIRE RPTING POS INQUIRIES BY OTHER ACFT WHEN IN THE AREA OF AN ARPT. REQUIRE RPTING POS IN THE LNDG PATTERN; DOWNWIND; BASE AND FINAL OR ANY COMBINATION OF TWO OF THESE WHEN THERE IS OTHER TFC IN THE PATTERN. REQUIRE STUDENT PLTS TO SO IDENT THEMSELVES WHEN XMITTING BY RADIO.