ACR GIVEN OFFSET TRACK; 5 MI W. ACKNOWLEDGED WITH READBACK. LATER GIVEN NEW TURN TO AVOID CONFLICT. ON HDOF QUESTIONED. MISCOM.

Narrative

ABOUT 7 HRS OF A 9 HR FLT FROM PARIS TO ST LOUIS HAD ELAPSED WHEN I GOT OUT OF MY SEAT TO STRETCH. THE ASSIGNED RELIEF PLT REPLACED ME AT THAT TIME AND I STEPPED TOWARD THE REAR OF THE COCKPIT; ABOUT 4 FT AFT OF THE PLTS. BOTH PLTS WERE ON HEADSETS AND TURNED TO ME SAYING THAT THEY HAD BEEN REQUESTED TO FLY AN 'OFFSET' TRACK 5 MI W OF OUR CURRENT TRACK. THEY WANTED TO CONFIRM THE FMC ENTRY AS THIS FUNCTION IS SELDOM USED. I LEANED FORWARD AND CONFIRMED THAT AN R5 ENTRY WAS CORRECT AND I FURTHER CAUTIONED THAT UPON EXECUTION; AN IMMEDIATE 45 DEG INTERCEPT WOULD OCCUR. BOTH PLTS AGREED THAT THIS IS WHAT WAS WANTED AND THEY PROCEEDED. NOT LONG AFTER; I NOTICED THAT WE WERE BEGINNING A HARD L TURN TO THE S USING THE HDG SELECT MODE OF THE AUTOPLT. I ASKED WHAT WAS HAPPENING AND THE PLTS SAID CENTER HAD GIVEN US THIS NEW TURN TO AVOID A POSSIBLE CONFLICT. I COULD TELL THAT THERE WAS SOME CONFUSION AND I RETURNED TO MY SEAT. IT WAS APPARENT THAT ANOTHER ACFT WAS ALSO ON VECTORS AND WE WERE SOON GIVEN A FREQ CHANGE TO THE NEXT CENTER (CHICAGO; I BELIEVE). THE NEW CTLR ASKED US TO EXPLAIN WHAT HAD TRANSPIRED AND MY FO EXPLAINED THAT THEY HAD RECEIVED; READ BACK AND THE PREVIOUS CENTER HAD ACKNOWLEDGED A 5 MI 'OFFSET' TO THE W. THE NEW CTLR INDICATED THAT THERE MUST HAVE BEEN A COMS BREAKDOWN AND WE SHOULD HAVE BEEN ISSUED INSTRUCTION TO 'OFFSET' 5 MI L (E). THIS ENTIRE EPISODE WAS A BIT DISTURBING TO ME AS I TRIED TO SORT OUT AND PIECE TOGETHER THE CTLR'S COMMENT WITH THAT WHICH I HEARD FROM MY CREW AND THAT WHICH I OBSERVED WHILE STANDING BEHIND THEM. AFTER SOME THOUGHT; I BELIEVE A CTLR SHOULD ISSUE SPECIFIC HDG INSTRUCTIONS TO BEGIN DIVERGING TRACKS FOR TFC AVOIDANCE. ONCE DIVERGENCE IS ESTABLISHED; FURTHER VECTORS OR AMENDED CLRNCS COULD BE ISSUED (I.E.; '...MAINTAIN THIS HDG TO INTERCEPT...). WE MUST ALSO GET SOME STANDARDIZATION IN COMS. THE WORDS W AND L ARE OBVIOUSLY SIMILAR AND APPARENTLY EASILY MISUNDERSTOOD. CTLRS SHOULD ALSO BE AWARE OF THE 45 DEG INTERCEPT/ESCAPE FUNCTION IN THE PROGRAM FOR OFFSETS AS FOUND ON THE WDB. IN LIEU OF VECTORS; THIS IS WHAT IS EXECUTED. CENTER SAID SOMETHING ALONG THE LINES OF 'NO PROBLEM' WHEN I RETURNED TO MY SEAT; BUT I FELT OBLIGATED TO RPT THIS TO NASA AS A POSSIBLE AREA OF CONCERN.