A TRACK DEV AND A LOSS OF SEPARATION ON THE NORTH AMERICAN RTE SYS.

Narrative

RERTE RECEIVED WHILE I (THE RELIEF PLT) WAS ABSENT FROM THE COCKPIT. WHEN I RETURNED; CAPT AND FO WERE DISCUSSING RERTE AND HAD A PROB WITH THE FMC. I LOOKED UP THE NEW RTE IN NORTH AMERICAN RTE; READ IT OUT TO CAPT FROM RELIEF PLT SEAT. CAPT AND FO RESOLVED PROB. CAPT LEFT COCKPIT; I SAT IN CAPT'S SEAT AND ASSUMED RADIO WORK. CAPT CALLED FROM CABIN ASKING ME TO ADVISE DISPATCH OF RERTE DUE TO RE-RELEASE OVER FIX ON PRIOR RTE. WHILE I WAS ENGAGED IN THIS ACTIVITY; FO HANDLED ACFT AND RADIO. WHEN I CAME BACK; I TOOK OVER RADIOS. NO CALLS WERE MISSED OR INQUIRIES MADE OVER PELEE. FO SAID 'WHY ARE WE OVER PELEE' AND ASKED MONTREAL IF WE WERE STILL ON A RADAR VECTOR. MONTREAL ADVISED US OF LOSS OF SEPARATION VIA SATCOM. CAPT HAD JUST RETURNED AND WAS NOT ENTIRELY BRIEFED. HE ASSUMED WE HAD A RADAR VECTOR BECAUSE THAT WAS WHAT FO HAD BELIEVED AND ADVISED THE CAPT AND MYSELF. THE 3 OF US DEBRIEFED COMPLETELY AND THE CAPT DIDN'T TAKE A CALL FOR THE VECTOR AND I HAD RECEIVED NO CALL SO IT IS MY ASSUMPTION THAT FO FAILED TO ENGAGE LNAV; UNLESS FO TOOK CALL FOR VECTOR AND THE FAULT WAS CTLR ERROR.