A CRJ PLT DEPARTED DTW WITH THE AUTOMATIC HDG MODE SELECTED. ATC COMMENTED THAT ACFT IN THAT MODE ARE OFF HDG DURING DEP.

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WE WERE OPERATING FLT FROM DTW. WE WERE CLRED FOR TKOF ON RWY 22 AND ASSIGNED A HDG OF 215 DEGS AFTER TKOF. ONCE AIRBORNE; WE STARTED THE TURN AT 400 FT AGL TO A HDG OF 210 DEGS AND WE WERE FLYING IN THE AUTOMATIC MODE WHICH IS OUR NORMAL TKOF PROC IN MAGNETIC MODE. AFTER STABILIZED AT A HDG OF 215 DEGS; ATC DEP CTL CAME BACK AND ASKED WHAT HDG WE WERE ON. WE SAID 215 DEGS. THEN HE CALLED TFC AT 11 O'CLOCK POS WHICH WE HAD HIM IN SIGHT. THEN HE TOLD US TO TURN TO A HDG OF 240 DEGS; WHICH WE DID. THEN HE ASKED IF WE TOOK OFF IN MANUAL OR AUTOMATIC MODE; WHICH WE REPLIED AUTOMATIC; WHICH IS OUR MAGNETIC MODE. THEN A MIN LATER HE GAVE US A PHONE NUMBER TO CALL ONCE WE REACHED OUR DEST. I CALLED THE SUPVR; ONCE ON THE GND; AND HE TOLD ME THEY HAVE HAD PROBS WITH THE CRJ TAKING OFF IN THE MANUAL MODE WHICH DOESN'T PUT THEM ON THE RIGHT HDG. HE ALSO ASKED FOR MY NAME AND PHONE NUMBER WHICH I GAVE HIM. HE ASKED IF I HAD ANY MEMOS OR MANUAL PROCS ABOUT TAKING OFF IN MANUAL OR AUTOMATIC. I SAID WE ALWAYS TAKE OFF IN AUTOMATIC. AS THE CONVERSATION ENDED; HE SAID HE WOULD CONTACT ME IF HE NEEDED EXTRA INFO. NORMAL FLT OPS WERE FOLLOWED. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATED THAT THE CRJ AUTOMATIC HDG MODE IS STABILIZED HDG AS OPPOSED TO THE MANUAL HDG WHICH IS UNCORRECTED FLUX VALVE HDG. THE AUTOMATIC HDG MODE IS HIS ACR'S ONLY DEP OPTION. RPTR STATED THAT THE REAL ISSUE AT THE ARPT IS THE MAGNETIC ANOMALIES THAT OCCUR WITH ACFT DEPARTING RWY 22L. THERE APPEARS TO BE SOMETHING IN THE DEP CORRIDOR CAUSING THE HDG ERROR OF +/-15 DEGS. RPTR STATED IN THE MANUAL HDG MODE THE ERROR WOULD BE WORSE BECAUSE CREWS WOULD FLY RAW HDG DATA THAT WOULD GREATLY LAG THE ACFT'S TURN.