AN MD11 FREIGHTER FLC TURNED OFF COURSE SHORTLY AFTER TKOF BECAUSE THE CAPT HAD ERASED SOME OF THE DEP INFO FROM THE FMC AND THEN SELECTED A NAV DISPLAY THAT FAILED TO INFORM THE FO ABOUT THIS SIT.

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I WAS PF. DURING 30 SECOND ANTI-ICE RUNUP ON RWY 16L; THE CAPT (A NEW CAPT) MADE AN ADJUSTMENT TO THE FMS FLT PLAN PAGE; THEN CHANGED PAGES TO A 'NAV RAD' PAGE WHICH ONLY DISPLAYS VOR AND ADF COURSE SELECTS/PRESELECTS. WE ARE REQUIRED TO HAVE THE FLT PLAN PAGE VISIBLE DURING TKOF. HE CHANGED MY SETUP FOR THE DEP SID OF RWY 16L; AND THEN CHANGED PAGES TO THE 'NAV RAD' PAGE; AND DID NOT TELL ME; OR SAY WHAT HE DID. AFTER TKOF AT APPROX 800 FT AGL; I ENGAGED THE AUTOFLT SYS AND NAV SYS; AND INSTEAD OF TRACKING DIRECTLY S ON THE 158 DEG RADIAL; THE ACFT MADE AN IMMEDIATE HARD R TURN TO THE NW. AS SOON AS THE HARD TURN BEGAN I DISENGAGED THE AUTOPLT; AND BEGAN A HARD TURN L TO REINTERCEPT THE REQUIRED COURSE. ATC (SEA DEP) ASKED US WHAT WE WERE DOING AND THE CAPT SAID WE WERE TURNING TO REINTERCEPT OUR COURSE. THE NEW CAPT FAILED TO TELL ME HE CLRED OUT MY DEP SETUP; AND ALSO QUICKLY HANDED ME THE ACFT RIGHT AT THE END OF THE 30 SECOND ANTI-ICE RUNUP; AND THEN DID NOT DISPLAY THE FLT PLAN PAGE AS REQUIRED; BUT CHANGED THE FMS TO THE NAV RAD PAGE. I WOULD HAVE CAUGHT THIS ERROR HAD THE CAPT EITHER TOLD ME HAD CHANGED MY SETUP; OR IF HE HAD DISPLAYED THE PROPER PAGE; AS REQUIRED BY OUR FLT OPS MANUAL. THERE WAS 'SECRET TYPING' BY THE CAPT; AND A COMS BREAKDOWN BY HIM NOT TELLING ME WHAT HE DID. IT APPEARS WE VIOLATED THE NOISE ABATEMENT PROC OFF OF RWY 16L AT SEA ARPT. THERE WERE NO OTHER ACFT IN THE AIR AT THE TIME. THERE WERE NO TFC CONFLICTS. I REALLY REGRET THIS SIT HAPPENING; AND SHOULD HAVE WATCHED THE CAPT MORE; AND STRESSED HE COMMUNICATE ANY FMS CHANGES TO MY FLYING LEG. WE SEEMED TO GET ALONG WELL. IT APPEARS AS IF IT WAS AN UNFORTUNATE AND HONEST MISTAKE. SUPPLEMENTAL INFO FROM ACN 433411: FO BRIEFED THE DEP AND INCORRECTLY BRIEFED RWY HDG VERSUS THE 158 DEG RADIAL. I TOLD HIM THAT THE SEA 158 DEG RADIAL WAS SET UP ON THE NAV RAD AND HE HAD HIS NAV DISPLAY ON 'VOR.' I HAD EVERY INDICATION THAT HE UNDERSTOOD THE DEP AND THAT HE WAS SET UP TO INTERCEPT THE RADIAL. AFTER TKOF AT APPROX 1000 FT THE FO SELECTED 'NAV.' THIS TURNED THE ACFT TO THE R TO INTERCEPT J523 INSTEAD OF INTERCEPTING THE 158 DEG RADIAL. AUTOPLT WAS ON. I NOTICED THE ERROR AFTER ABOUT 30 DEGS OF TURN AND IMMEDIATELY ASKED THE FO WHERE WE WERE GOING. HE DISENGAGED THE AUTOPLT AND RETURNED THE ACFT TO A 158 DEG HDG. I THEN PROMPTED HIM TO INTERCEPT THE RADIAL. ATC CALLED AND ASKED WHY WE WERE OFF COURSE. I REPLIED THAT WE WERE 'CORRECTING' BACK TO COURSE. WE WERE LATER VECTORED TO INTERCEPT J523.