AN LGT FLYING IN ZAU AIRSPACE FAILS TO FOLLOW HEADING COMMANDS FROM ARTCC.

Narrative

I WAS THE PNF; THE FO WAS FLYING; WITH AN FAA INSPECTOR IN THE JUMP SEAT. APCHING DUBUQUE; I TOLD THE FO I WAS LEAVING THE FREQ TO GET ORD ATIS; THAT HE HAD THE RADIO FOR ATC; AND THE AIRPLANE. I TURNED MY VOLUME CTL FOR ATC TO OFF SO I COULD CONCENTRATE ON THE ORD ATIS. WHILE I WAS OFF; THE AIRPLANE BANKED R; THEN THE FO RESPONDED TO CTR AGAIN; AND BANKED 25 DEGS L. AT THIS TIME I CAME BACK UP AND SAID 'WHAT'S GOING ON.' BEFORE THE FO COULD RESPOND; ATC CALLED WITH A FREQ CHANGE. CHKED IN WITH THE NEW FREQ; AND WERE IMMEDIATELY INTO THE APCH AND ARR PHASE OF THE FLT; AND WAS TOO BUSY TO FOLLOW UP WHAT HAD JUST HAPPENED. AFTER LNDG; TAXI IN AND SHUT DOWN; I TURNED TO THE INSPECTOR AND SAID; 'ANY COMMENTS.' HE RESPONDED 'NOT FOR YOU.' HE THEN TOLD THE FO 'WHEN ATC GIVES YOU INSTRUCTIONS; YOU'D BETTER LISTEN UP.' EVIDENTLY WHAT HAD HAPPENED WAS WE WERE HEADING APPROX E; 090 DEGS; AND CTR GAVE US A R TURN; HDG 040 DEGS. THE INSPECTOR AGREED. THE FO; INSTEAD OF QUERYING ATC ABOUT THE CONFLICT ASSUMED THE HEADING WAS IN ERROR; AND TURNED R TO 140 DEGS. WHILE WE WERE IN THE TURN; CTR SAID 'CONFIRM YOU'RE IN THE TURN;' TO WHICH THE FO RESPONDED AFFIRMATIVELY. CTR THEN SAID TURN FURTHER R 030 DEGS; AT WHICH TIME MY FO REALIZED THE PROB AND INITIATED THE L TURN; AND I CAME BACK ON.