A CRJ200 PLT RPTS A HDG DRIFT ON DTW RWY 22 BEFORE TKOF AND A TRACK DEV AFTER TKOF CAUSED BY THE ACFT COMPASS SYSTEM HDG DRIFT.

Narrative

ON TAXI ON TO RWY 22L IN DTW THE EFIS COMP CAUTION COME ON WHEN WE PULLED ON TO RWY 22L WE SLEWED THE FO'S HEADING AS THE CAPT'S HEADING ALIGNED WITH RWY 22L. WE RECEIVED TAKEOFF CLRNC WITH A HEADING OF 200 DEGS AFTER TAKEOFF. WE STARTED OUR ROLL AND JUST AFTER TAKEOFF WE AGAIN RECEIVED THE EFIS CAUTION; AT 400 FT AGL I TURNED TO 200 DEG AND THEN RECEIVED A CALL TO TURN BACK TO RWY HEADING; ON THE WAY BACK TO 220 DEG. WE THEN WE RECEIVED A CALL TO LOOK FOR A DC9 DEPARTING RWY 21R WE HAD HIM AND CALLED HIM IN SIGHT; WE THEN TURNED BACK TO 200 DEG AFTER RECEIVING DIRECTION OF DTW TOWER AND WERE TOLD TO MAINTAIN THE DC9 IN SIGHT. THROUGH 600 FT AGL THE AUTOPILOT WAS TURNED ON AND WE THEN STARTED COMPARING MINE AND THE FO'S HEADING TO THE STANDBY COMPASS AND AGAIN FOUND THAT THE FO'S HEADING WAS OFF. I THEN HAD THE FO RUN CHAPTER 7 IN THE POM WHILE I CONTINUED COMPARING THE HEADING TO THE STANDBY COMPASS. THE FO COMPLETED CHAPTER 7 AND RETURNED HIS HEADING TO 200 DEG. WE THEN MONITORED THE HEADING TO THE STANDBY COMPASS WHEN THE EFIS COMP CAUTION CAME ON AGAIN; THEN WE FLEW USING THE STANDBY COMPASS AGAIN UNTIL THE FO'S HEADING WAS AGAIN SLEWED TO THE STANDBY COMPASS AND THAT FIXED THE PROBLEM. WE CONTINUED ON A 200 HEADING WITH THE DC9 STILL IN SIGHT. WE THEN RECEIVED A CALL HAVING US CALL DTW WHEN WE LANDED AND WHEN ON THE GND IN ZZZ; I FOUND THAT OUR HEADING WAS APPARENTLY UP TO 25 DEGS OFF (GROUND TRACK). I DON'T SEE HOW THAT'S POSSIBLE SINCE THE HEADING WAS ALWAYS COMPARED THE HEADING WITH THE STANDBY COMPASS. HIGH WORKLOAD ON TAKEOFF WITH CHANGES TO HEADINGS JUST AFTER TAKEOFF AND THE CHAPTER 7 IT WOULD TAKE A GREAT DEAL OF TIME TO GET TO THE PART WERE IT SAYS ANYTHING ABOUT THE AUTOPILOT; PERHAPS WHEN THAT CAUTION COMES ON THE AUTOPILOT SHOULD BE OFF AND FLY WITH THE STANDBY COMPASS UNTIL THE PROBLEM IS SOLVED.CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THAT HE IS NEW TO THE ACFT BUT HE HAS SEEN THE COMPASS ANOMALY BEFORE AT DTW. AMONG THE PLTS THE FEELING IS TO JUST ACCEPT THAT THE COMPASS CAUTION WILL OCCUR ESPECIALLY AT THE GATE. THE EXTENT OF THE DEV IN THIS EVENT WAS UNUSUAL BECAUSE OF THE LENGTH OF TIME IT LASTED. TO THE RPTR'S KNOWLEDGE; NO ONE HAS ATTEMPTED TO EXPLAIN WHY THE COMPASS ANOMALY OCCURS AT DTW.