SMA PLT HAD AN NMAC ON FINAL TO AN UNCONTROLLED ARPT.

Narrative

RPTR FLEW THE GPS RWY 23 APCH TO SHN FOR PRACTICE. AT ABOUT 7 MI FROM THE RWY THRESHOLD; CHANGED THE #1 COM RADIO (KING 155) FREQ TO THE CTAF 122.8; BUT DID NOT PUSH THE FLIP-FLOP SWITCH HARD ENOUGH TO CHANGE THE FREQ; AND DID NOT CHK THE INDICATION TO ENSURE XMISSION ON THE CORRECT FREQ. ANNOUNCED ON WRONG FREQ; ACFT IDENT AT SANDERSON FIELD; AND INTENTION TO PERFORM LOW APCH TO RWY 23. UPON DSNDING TO AND REACHING 1000 FT MSL AT APPROX 3 MI FROM THE THRESHOLD; OBSERVED WRONG COM FREQ SELECTED; SWITCHED FREQS TO CORRECT FIELD FREQ; AND HEARD ANNOUNCEMENT OF A MOONEY TURNING FINAL TO RWY 23. IMMEDIATELY LOOKED OUT TO L; AND OBSERVED MOONEY AT 9 O'CLOCK POS AND CONVERGING; ABOUT 100 FT UNDER MY ACFT; IN L-HAND TURN TO FINAL APCH COURSE. IMMEDIATELY APPLIED PWR AND INITIATED CLBING L-HAND TURN TO LEAVE MOONEY TO R OF RPTR ACFT. EVENT OCCURRED DUE TO VIOLATION OF FUNDAMENTAL RULE OF FLT OF TAKING ALL NECESSARY ACTIONS TO SEE AND BE SEEN. RPTR WAS UNAWARE OF OTHER ACFT IN DOWNWIND AND BASE LEG TO ACTIVE RWY BECAUSE OF NOT SELECTING CORRECT FIELD FREQ; AND BECAUSE OF PERFORMING ONLY CURSORY VISUAL CHKS OF THE OPERATING ENVIRONMENT FOR OTHER ACFT. RPTR FOCUSED TOO MUCH ATTN ON INST DISPLAYS AND LNDG RWY VERSUS OTHER AREAS OF POTENTIAL IMPACT. CONTRIBUTING TO THE POTENTIAL PROB; THE MOONEY DID NOT DISPLAY VISIBLE NAV LIGHTS NOR STROBE LIGHTS ON THE FUSELAGE NOR WINGS; AND WAS THEREFORE DIFFICULT TO SEE WITHOUT CLOSE SCRUTINY IN FADING LIGHT. RPTR'S ACFT WAS OPERATING NAV LIGHTS AND WINGTIP; DOUBLE FLASH STROBES; BUT APPARENTLY WAS NOT OBSERVED BY MOONEY PLT DUE TO PLT'S ATTN DIVERTED TO L OF ACFT (ONLY) IN PREPARATION FOR LNDG. TO PREVENT RECURRENCE; RPTR WILL BE MUCH MORE EMPHATIC ABOUT SEEING AND BEING SEEN; PARTICULARLY IN THE NEAR-ARPT ENVIRONMENT.