NMAC BETWEEN 2 GA-SMA.

Narrative

I WAS FLYING SMA X IN SUPPORT OF RADIO. DURING THE COURSE OF THE FLT I WITNESSED 2 FLT VIOLATIONS. THE FIRST VIOLATION OCCURRED W OF CHICAGO'S LOOP AREA. WHILE FLYING S ALONG OGDEN AVE FROM THE LINCOLN PARK AREA AT 1300' INDICATED; I SAW A HIGH WING SMA Y ACFT APCH EBND ON THE N SIDE OF THE EISENHOWER EXPRESSWAY. I HEARD THE SMA Y IDENT ITSELF TO MEIGS TWR AS XYZ. THE SMA Y CONTINUED E UNTIL OVER THE INTXN OF THE EISENHOWER AND THE DAY RYAN EXPRESSWAY. THE SMA Y THEN TURNED S ON THE E SIDE OF THE DAN RYAN. THROUGHOUT THIS PERIOD THE ACFT MAINTAINED THE SAME ALT. I HAD JUST RECEIVED AN UPDATED ALTIMETER SETTING FROM MIEGS TWR. THE FIELD ELEVATION AT MEIGS IS 595'. THE SECOND VIOLATION OCCURRED APPROX XA35 ON THE SAME MORNING. WHILE FLYING SBND ALONG THE TRI STATE EXPRESSWAY ON THE E SIDE BTWN OGDEN AVENUE AND THE HINSDALE OASIS; I WAS PASSED ON THE LEFT BY A HIGH WING SMA Y AT THE ALT; 1300' INDICATED. THE SMA Y WAS WITHIN 100' OF MY ACFT WHEN IT PASSED. I WATCHED THE SMA Y CONTINUE TOWARDS MIDWAY ATA. I TUNED MY RADIO TO MIDWAY TWR FREQ AND HEARD THE SMA Y IDENT ITSELF AS XYZ. I CONTINUED TO TRACK THE LOCATION OF SMA Y UNTIL IT WAS TAXIING INTO PARKING AREA. AT THAT TIME I FLEW NEAR THE ACFT ON MY APCH TO LNDG ON THE S RAMP. IT WAS A HIGH WING SMA Y ON THE BOTTOM WITH STRIPES AND A DARK TOP. I COULD NOT READ THE LETTERS BECAUSE THEY WERE SO SMALL.