A FLC HAD A NEAR MISS WITH AN ACFT NEAR PLN.

Narrative

WHILE ON AN IFR FLT PLAN IN VMC; OUR ACFT WAS CLRED TO DSND FROM 10000 FT TO 4000 FT BY ZMP. DURING THIS DSCNT; I SPOTTED OPPOSITE DIRECTION TFC SLIGHTLY BELOW US. DUE TO THE CLOSE PROX OF THE TFC (LESS THAN 1 MI) I SHOUTED 'TFC' AND POINTED STRAIGHT AHEAD. THE CAPT LOOKED UP AND BANKED THE ACFT 60-90 DEGS L TO AVOID A COLLISION. THE OTHER ACFT PASSED BY OUR R SIDE AT APPROX 200-300 FT; AND ABOVE US ABOUT 200 FT OR SO. WE WERE NOT ADVISED BY ATC OF ANY TFC AND WERE VERY SHOCKED AT WHAT HAD JUST HAPPENED. I THEN TOLD CTR THAT WE HAD JUST MISSED HITTING ANOTHER ACFT AND ASKED IF HE HAD US IN RADAR CONTACT. HE CONFIRMED WE WERE UNDER RADAR CONTACT AND THAT THE OTHER ACFT WAS VFR AND WAS NOT TALKING TO HIM. AT THIS TIME THE OTHER ACFT CALLED ON FREQ AND STATED HE WAS THE ACFT WE ALMOST HIT AND THAT HE WAS UNDER 'VFR ADVISORIES.' CTR AND THIS OTHER ACFT ATTEMPTED TO IRON OUT THIS CONFUSION. WE WERE 10 NM FROM PELLSTON (OUR DEST) AND HAD THE ARPT IN SIGHT. WE TERMINATED IFR WITH CTR AND PROCEEDED VISUALLY INTO TFC AND LANDED. AFTER CONVERSATIONS WITH CTR SUPVR AND CTR QUALITY ASSURANCE MGRS; IT IS APPARENT THAT THIS GEOGRAPHICAL AREA IS A HAVEN FOR VFR PLTS DURING SUMMER MONTHS. THERE IS ALSO AN INCREASED VOLUME OF IFR (CPR) JET TFC ALONG WITH COMMUTER TFC DURING THIS SAME TIME FRAME. IT IS ALSO APPARENT THAT THE ATC SYS FAILED IN ITS PRIMARY JOB OF TFC SEPARATION FOR OUR ACFT IN THIS AREA. SEE AND AVOID HAS TAKEN ON A NEW MEANING TO ME.