NMAC BTWN AN SMA SEL DEPARTING AT 500 FT AGL AND AN ARRIVING UNKNOWN ACFT AT 600 FT. RPTR TOOK EVASIVE ACTION BY SIDESTEPPING TO THE SIDE.

Narrative

TKOF NORMAL ON MRI RWY 15 AND CHESTER CREEK DEP WAS FLOWN. 1 MIN INTO FLT; NOW WBOUND AND 500 FT MSL; AN EBOUND ACFT WAS OBSERVED AT 12 O'CLOCK AND 2 MI AND 600 FT. TURNED LNDG LIGHT ON AND SIDESTEPPED N 300 FT TO INCREASE CLRNC TO OPPOSING ACFT. OBSERVED OTHER ACFT TURNING S; AS WE PASSED UNEVENTFULLY; 100 FT VERT; 400 FT HORIZ CLRNC. AT TIME OF PASSING OTHER ACFT WAS 1/4 MI N OF 'WEST HI' RPTING POINT FOR MRI RWY 33. THE OTHER PLT ANNOUNCED A 'NEAR MISS' ON MRI TWR FREQ 126.0; WITH ONE REPEAT. I ANNOUNCED ON SAME FREQ AFTER A MIN DELAY THAT IT WAS NOT 'CLOSE' AND THAT I HAD THE ACFT IN SIGHT. THE DELAY WAS CAUSED WHILE LOOKING FOR A SECOND ACFT ON THE SAME APCH TO MRI. I CONSIDERED THE EVENT UNREMARKABLE AND DID NOT CONTEMPLATE FILING THIS RPT; UNTIL I FOUND THAT THE OTHER PLT DID NOT HAVE THE SAME OBSERVATIONS. SEE AND BE SEEN IS A MUST AS WELL AS OVERFLYING RPTING POINTS; IN THESE CTL SEGMENTS. FREQ CONGESTION OCCASIONALLY PREVENT ANNOUNCING ARR AT RPTING POINTS; BUT BEING ON AN EXPECTED RTE PREVENTS TFC CONFLICT.