CLOSE PROX GA-SMT GA-UNK ON AIRWAY V220.

Narrative

THE RPTR'S ACFT (#1) WAS EBND ON V-220 AT 11000' MSL IN IMC CONDITIONS AT APPROX 65 NM W OF MCK VOR AND IN CONTACT WITH DEN CENTER. AT APPROX 50 NM W OF MKC VOR I BECAME VMC AND NOTICED AN ACFT (#2) POS LIGHTS AT MY 11 O'CLOCK POS; HEADING THE OPP DIR ON V-220 AND INITIALLY APPEARED HIGHER THAN I WAS. I HAD JUST BEEN GIVEN THE CURRENT MKC ALTIMETER SETTING AND APCH CLRNC BY DEN CENTER. I ADVISED DENVER CENTER THAT I HAD AN ACFT ON VISUAL AT 11 O'CLOCK. CENTER REPLIED THAT HE DID NOT HAVE MODE C ON THE ACFT THAT I RPTED. ACFT (#1) REMAINED AT 11000' MSL AND CONTINUED TO OBSERVE ACFT (#2). AS ACFT (#2) APCHED HE DISPLAYED HIS LNDG LIGHTS AND DID NOT CHANGE HIS DIRECTION OR ALT. ACFT (#1) DISPLAYED HIS LNDG LIGHTS AND MADE AN EVASIVE 45 DEG RIGHT BANK TO AVOID ACFT (#2). ACFT (#1) HAD APPROX 60 SECS OF VISUAL CONTACT PRIOR TO THE EVASIVE RIGHT BANK. ESTIMATED MISS WAS APPROX 150-300' HORIZ AND 20' VERT; ACFT (#2) BEING HIGHER THAN ACFT (#1). I ADVISED DEN CENTER OF NEAR MISS AND REQUESTED THAT A RPT BE FILED. I BELIEVE THAT ACFT (#2) WAS AT THE INCORRECT ALT IN RELATIONSHIP TO THE DIRECTION OF TRAVEL; IMPROPER FLT PLANNING DUE TO IMC CONDITIONS WITHIN THE AREA AND AT NIGHT; DISREGARD TO ACFT (#1) BY NOT USING PROPER PROCS WHEN ENCOUNTERING AN ACFT HEAD ON. LNDG LIGHTS ALONE WILL NOT PREVENT AN ACCIDENT. ADDITIONAL COMPLICATIONS WERE DUE TO DEN CENTER NOT ADVISING ACFT (#1) OF THE PRESENCE OF ACFT (#2). I RPTED THE ACFT TO CENTER; ALMOST TOO LATE. MANDATORY MODE C FOR ALL ACFT COULD POSSIBLY HAVE PREVENTED THIS SITUATION IF CENTER WOULD HAVE RPTED SUCH ACFT.