SMA HAS NMAC WITH SECOND SMA IN TFC PATTERN.

Narrative

CALLED THE TWR FOR LNDG INSTRUCTIONS; (CLASS D) POS WAS AROUND 7 MI SW OF ARPT. TOLD TO RPT A 3 MI FINAL FOR RWY 05. ALSO WAS ISSUED A LNDG SEQUENCE; #2; 'FOLLOWING ANOTHER ACFT;' ACKNOWLEDGED BOTH. I WAS INITIALLY SCANNING FOR THE PRECEDING ACFT BUT COULD NOT FIND IT. SEVERAL MINS LATER I ASKED THE TWR WHERE THE ACFT WAS AT. THE TWR REPLIED '1/2 MI FINAL.' AT THIS TIME OR SHORTLY THEREAFTER I RPTED A 3 MI FINAL. I WAS; 'CLRED TO LAND; #2.' THINKING THAT THERE WAS ENOUGH DISTANCE BTWN MYSELF AND THE PRECEDING ACFT; BASED ON THE TWR'S RPT; I FAILED TO SCAN AGGRESSIVELY FOR THE PRECEDING PLANE. THEN I CAUGHT UP TO THE PRECEDING ACFT AT APPROX A 1.5 MI FINAL. HE WAS ABOVE ME AND OFF TO MY SIDE. HE WAS STILL SOME DISTANCE IN FRONT OF ME TOO; APPROX 200 FT. HAD I BEEN SCANNING MORE AGGRESSIVELY I WOULD HAVE SEEN HIM SOONER. I REQUESTED A '360 DEG' FROM THE TWR FOR SEPARATION AND IT WAS APPROVED. HE SAW ME RE-ESTABLISHED ON FINAL AND CLRED ME TO LAND AGAIN. AT THE COMPLETION OF THE 360 DEG TURN THERE WAS MORE THAN ADEQUATE SEPARATION. THE TWR CLRED ME TO THE RAMP AND NOTHING WAS SAID BY EITHER THE TWR OR THE PRECEDING ACFT. I PLACED TOO MUCH RELIANCE ON THE TWR'S ACCURACY AND FAILED TO CONTINUE TO SCAN AGGRESSIVELY FOR THE PRECEDING ACFT. I DO UNDERSTAND THAT ONCE ISSUED A LNDG SEQUENCE THAT IT IS MY RESPONSIBILITY TO MAINTAIN SAFE SEPARATION BTWN MYSELF AND ANY PRECEDING ACFT. IN THE FUTURE I WILL PLAN NOT TO ASSUME THE ACCURACY OF A TWR OR OTHER PLT'S POS RPT AND PLAN TO FLY MORE DEFENSIVELY.