NMAC BETWEEN 2 GA-SMA'S.

Narrative

I WAS ON AN IFR FLT PLAN FROM MSN TO 1C5. ALT ASSIGNED IN CHICAGO APCH AIRSPACE WAS 4000'; CONDITIONS WERE VFR 5-6 MI. WHEN I LEFT MADISON; IT WAS 1100 BKN RAINING WITH CONDITIONS IMPROVING AS I BACKED THROUGH A COLD FRONT. AS I WAS HANDED OFF FROM ROCKFORD TO CHICAGO AIRSPACE. CHICAGO SEEMED TO BE HAVING DIFFICULTY HEARING ME AND OTHER ACFT. I CALLED 5 TIMES; ANOTHER ACFT CALLED 5 TIMES AND ANOTHER THE CTLR COULDN'T HEAR AT ALL (ALTHOUGH I COULD). THE CTLR WAS GETTING FRUSTRATED WITH THE INABILITY TO HEAR US. (I DON'T KNOW IF THIS CONTRIBUTED OR NOT TO NOT SEEING OR RPTING TFC.) THEY WANTED ME TO GO DIRECT JOT VOR AND DSND TO 4000' WHICH I DID. OVER AUBURN IT WAS GETTING TO BE VFR AND I WAS JUST ABOUT READY TO CANCEL IFR WHEN A TWIN SMA CUT RIGHT ACROSS MY FLT PATH; FROM LEFT TO RIGHT. I DON'T REMEMBER MOVING THE ACFT. IT HAPPENED SO FAST. MY HDG WAS ABOUT 150 DEGS. HIS MUST HAVE BEEN ABOUT 270-290 DEGS AND 4100'. I DON'T BELIEVE HE TOOK ANY EVASIVE ACTION. I RECALL HIM BEING SO CLOSE I COULD READ HIS NUMBERS WHICH WERE XX. HE WENT BY SO FAST THE ONLY ONE I RECALL WAS THE FIRST ONE. I TOLD APCH ABOUT THE NEAR MISS AND I TALKED TO THE SHIFT SUPVR ON THE GND BY PHONE. HE STATED; WHEN I CALLED THE NEAR MISS; THE CTLR CALLED HIM OVER TO THE SCOPE AND THEY DID NOT SEE ANY INTERFERING TFC AT ALL. I FILED A RPT WITH THE AREA MGR AND HE SAID HE WOULD REVIEW THE TAPES. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING: RPTR HAS HEARD NOTHING BACK FROM THE SUPVR ON THE TAPES; BUT SINCE SUPVR LOOKED AT SCOPE AND COULD FIND NO TARGET WAS PROBABLY NON TRANSPONDER AND CONSEQUENTLY TAPES WILL SHOW NOTHING. OTHER SMA WAS GOING WNW; PROBABLY HEADED FOR DPA OR RFD.