NMAC BTWN A SMA SEL LOW WING DSNDING TO THE DOWNWIND LEG AND A CESSNA 152 CLBING OUT AFTER TKOF AT A CTLED ARPT. THE RPTR DID TAKE EVASIVE ACTION TURN AND CLB.

Narrative

THIRD LEG (MVN DIRECT CPS) WAS ALSO UNEVENTFUL UNTIL LAST CHKPOINT WAS PASSED. LAST CHKPOINT PASSED AT 2000 FT MSL ON HDG OF 275 DEGS. TWR CONTACTED APPROX 1 MI PAST LAST CHKPOINT AND INFORMED AT 2000 FT. DSCNT STARTED FROM 2000 FT MSL TO 1200 FT MSL (PATTERN ALT) AFTER CONTACTING TWR. VISIBILITY POOR DUE TO SUN BEING DIRECTLY OPPOSITE FLT PATH. 2 CESSNA 150'S WERE HEARD ON TWR FREQ AS DEPARTING THE PATTERN; 1 NBOUND AND OTHER EBOUND. SUBSEQUENTLY; SCANNING PROCS INITIATED IMMEDIATELY. AT APPROX XA40 LCL; I LOOKED AROUND THE DOOR POST AND OBSERVED A CESSNA 150 CLOSING AT A HDG OF 045 DEGS IN A CLB ALT. AT THIS POINT ROUGHLY 3 SECONDS FROM COLLISION; I ENTERED A 20 DEG BANK TO R AND A CLB ATTITUDE. CESSNA 150 NEVER OBSERVED TO ALTER COURSE; PASSED 100-200 FT VERTLY AND 20-100 FT HORIZLY BELOW ACFT AND TOWARDS TAIL SECTION. FLT COMPLETED WITHOUT FURTHER INCIDENT. I BELIEVE THAT CONTRIBUTING FACTORS TO THIS INCIDENT INCLUDE THE SUN (POOR VISIBILITY) AND LACK OF RADAR SURVEILLANCE BY TWR CTLRS AT CPS. INCIDENT COULD NOT HAVE BEEN PREVENTED AT ANY TIME BY TWR CTLRS DUE TO LIMITED RESOURCES. SEE AND AVOID WAS FOLLOWED; BUT DOOR POST OBSTRUCTION PERMITTED THE ACFT TO APCH UNOBSERVED UNTIL APPROX 3 SECONDS FROM COLLISION. INCIDENT WAS NOT RPTED TO TWR AS A NEAR MID- AIR COLLISION DUE TO POSSIBLE ENFORCEMENT ACTION BY FAA. OTHER PLT DID NOT RPT DUE TO UNKNOWN REASONS; BUT BELIEVED TO BE UNAWARE OF INCIDENT SINCE HE FAILED AT ANY TIME TO ALTER COURSE. SINCE I AM TRAINING TO BE A PROFESSIONAL PLT; I BELIEVED IT AN UNNECESSARY RISK TO MY CAREER IN THE FUTURE TO INVOLVED HE FAA IN THIS SIT SINCE ENFORCEMENT ACTION (PART 91.13; AIM 7-92; ETC) HOWEVER UNLIKELY; WAS POSSIBLE.