FLC OF MLG MAKES SEVERAL APCH ATTEMPTS PRIOR TO DISCOVERING FLT MGMNT SWITCHES IN WRONG POS ARRIVING ATL.

Narrative

FIRST AND FOREMOST; IT SHOULD BE KNOWN THAT AN EXTREMELY BAD (HOSTILE) CRM ENVIRONMENT HAD DEVELOPED THE DAY PRIOR AND CARRIED OVER FOR THE REMAINDER OF THE TRIP! ON THE MACEY 2 ARR INTO ATLANTA; WE WERE GIVEN HOLDING INSTRUCTIONS AT MACEY AT ABOUT FL200. FOLLOWING OUR ENTRY INTO HOLDING; I NOTICED THE CAPT CHANGED THE FRONT COURSE SET IN THE MCP TO REFLECT OUR HOLDING COURSE (WE BOTH CHANGED COURSE). WE BOTH HAD THE LOC RWY 26R FRONT COURSE DIALED IN; AND SETTING THE HOLDING COURSE IN WAS SUPERFLUOUS SINCE THE HOLDING COURSE WAS SET IN THE FMC AND WE WERE IN AN AUTOMATED HOLDING MODE WITH THE MCP IN THE NAV POS. AFTER 1 TURN IN HOLDING; ATL GAVE US A VECTOR FOR THE LOC AND WE WERE TOLD TO DSND AND INTERCEPT THE FINAL APCH COURSE. I SWITCHED THE NAV SYS FROM THE NAV MODE TO THE VOR/ILS MODE AND CALLED FOR THE APCH CHKLIST. ONE ITEM OF THE APCH CHKLIST IS TO ENSURE THE FINAL APCH COURSE IS DIALED IN. THE PLT MONITORING VERBALLY 'ACCOMPLISHED' THE CHKLIST AND CALLED IT COMPLETE. HOWEVER; THE FINAL APCH COURSE WAS NEVER CHANGED FROM 221 DEGS (HOLDING COURSE) TO 264 DEGS (APCH COURSE). UPON REACHING THE LOC INTERCEPT POINT; THE FRONT COURSE WAS CAPTURED; BUT THE HOLDING COURSE IN THE MCP WAS TRACKED. WE RPTED 'OFF FLAGS' AND ATL GAVE US A NW VECTOR TO REINTERCEPT AND THE CYCLE WAS REPEATED. AGAIN; ATL GAVE US A STEEPER VECTOR BACK TO THE LOC AND INQUIRED IF WE HAD THE PROPER FREQ DIALED -- WE DID. AT THAT TIME; THE CAPT SAID; 'YOU HAVE THE WRONG FRONT COURSE DIALED IN!' I POINTED TO HIS SIDE AND SAID;' SO DO YOU!' THE CAPT TOOK THE ACFT FROM ME AND FLEW NW UNTIL A VISUAL ON RWY 26R WAS ACQUIRED. HE THEN GAVE ME THE ACFT FOR LNDG. I DON'T KNOW IF SEPARATION WAS LOST. INITIALLY IT WAS VERY CONFUSING! I THINK THE HOSTILE CRM ENVIRONMENT WAS THE MAIN CATALYST TO THIS INCIDENT. I'M OBVIOUSLY CERTAIN OF IT!