SMT CARGO ACFT HAS NMAC WITH SMA AT UNCTLED ARPT.

Narrative

NIGHT CARGO (SMT) ORIGINATED AT MKE WITH STOPS AT GRB AND IMT AND TERMINATING AT MQT. THE FIRST 2 LEGS WERE IFR AND THE THIRD VFR. NO RADIO PROBLEMS WERE RPTED OR NOTED. ON THE THIRD LEG I WAS WORKING THE RADIOS. I MADE A REQUEST TO THE MARQUETTE UNICOM FOR AN ADVISORY; AFTER RECEIPT I ANNOUNCED POS AS 10 MI SW AND WOULD BE ENTERING L TFC FOR 26. THE NEXT CALL WAS A 2 1/2 MI L DOWNWIND RWY 26 MQT. SO FAR WE HAD NEITHER SEEN NOR HEARD ANY TFC IN THE MQT AREA. AS THE PLT WAS TURNING BASE WE HEARD SMA ON MID FIELD DOWNWIND RWY 26. WE DID NOT HAVE THE TFC IN SIGHT AND I MADE THE BASE CALL. THE PLT ASKED SMA FOR POS AND ALT AND REPLY WAS 'DOWNWIND 2000 FT' (PATTERN ALT; 2200). WE THEN SIGHTED THE SMA AND THE PLT MADE AN ABRUPT CLBING TURN HEADED DOWNWIND AND I MADE THE ANNOUNCEMENT. THE NEXT CALL I MADE WAS REENTERING THE PATTERN ON A 4 1/2 MI FINAL. WE NO LONGER HAD THE SMA IN SIGHT OR HEARD ANY POS RPTS. AFTER INQUIRY; THE SMA PLT STATED HE WAS ON L BASE 26. AFTER INQUIRY AGAIN; HE STATED HE WAS 2 MI BEHIND US. MY NEXT 2 POS RPTS WERE 2 MI FINAL 26 AND CLRING RWY 26. I ATTRIBUTE THE COM PROBLEM TO NOTORIOUSLY POOR RADIOS IN SMA AND AN OVERTASKED CFI. THE GREEN AND WHITE ACFT WAS EXTREMELY DIFFICULT TO SEE WITH THE TREES IN THE BACKGND (ENTIRE FLT ON TAPE).