THE FLT WAS NORMAL UNTIL THE PLT WAS TRACKING INBND ON THE ATLANTA (ATL) 128 DEG RADIAL TWD THE HUSKY INTXN & WAS TOLD TO MAKE A 360 DEG TURN FOR SPACING. AFTER APRX 270 DEG OF TURN, THE PLT WAS CLRD TO TURN BACK INBND, JOIN THE ATL 128 DEG RADIAL & CONT TO THE HUSKY INTXN, THEN PROCEED DIRECT TO THE PEACHTREE DEKALB ARPT. INSTEAD OF TURNING INBND (NW), THE ACFT TURNED OUTBND (SE) TO A HDG OF 128 DEG. WHEN ASKED ABOUT HIS HDG, HE SAID HE HAD AN AUTOPLT PRBLM, BUT GAVE NO EXPLANATION. THE PLT WAS PROVIDED A VECTOR BACK TO THE NW, THEN CLEARED DIRECT TO THE VOR. HOWEVER, THE ACFT AGAIN TURNED BACK TO THE SE. WHEN ASKED IF THE AUTOPLT WAS ON AGAIN, THE PLT SAID NO. ANOTHER VECTOR WAS PROVIDED TO TURN BACKTOWARD THE NW. THE ACFT BEGAN TURNING, BUT SUBSEQUENTLY, IT ENTERED A STEEP DESCENT & CRASHED. A WITNESS REPORTED HEARING THE ENGS AT HIGH POWER UNTIL THE ACFT DESCENDED OUT OF THE CLOUDS. THE ACFT WAS EXTENSIVELY DAMAGED DURING IMPACT. NO PREIMPACT PART FAILURE OR MALFUNCTION WAS VERIFIED DURING THE INVESTIGATION.