A B777 FLC FAILS TO FOLLOW THE SID AS PORTRAYED ON THE DEP CHART. THEY EXPERIENCE A HDG TRACK POS DEV JUST W OF CDG. FO COMPLAINS OF CHART DESIGN AND PRESENTATION.

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DEPARTING CHARLES DE GAULLE RWY 27; BNE 8D DEP. AFTER TKOF FROM CDG; RWY 27; WE BEGAN A SLOW R TURN TO INTERCEPT THE BT 331 DEG RADIAL AS PER THE WRITTEN INSTRUCTIONS ON THE SID. PASSING APPROX 2000 FT; ATC ADVISED US TO TURN TO A HDG OF 270 DEGS BECAUSE 'WE HAD TURNED EARLY.' AFTER REACHING CRUISE ALT; WE EXAMINED THE PROC AND THE ARROWS/LINES ON THE SID DIAGRAM SHOWED A TURN AT 1.5 DME. TO OUR KNOWLEDGE THERE WAS NO TFC CONFLICT. FACTORS THAT CONTRIBUTED TO THIS INCLUDE RELIANCE ON THE DIRECTION OF THE 'MAGENTA LINE' ON THE FMC/EFIS WHICH SHOWED DIRECT TO THE 8.5 MI FIX OF THE BT 331 DEG RADIAL. ANOTHER MAJOR CONTRIBUTING FACTOR WAS THE LACK OF WRITTEN INSTRUCTION NOT TO TURN PRIOR TO 1.5 DME; AND THE FACT THAT THE SYMBOL USED TO SHOW THIS POINT ON THE SID DIAGRAM IS EASILY MISTAKEN AS THE SYMBOL FOR A NOISE MONITORING POINT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE FO HAD OFFERED A COPY OF THE CHART WHICH IS NOT AVAILABLE TO ANALYST. FO ADMITTED THAT HE WAS FAIRLY NEW TO THE INTL OP. HE WOULD LIKE THE CHART PRODUCER TO REVIEW THIS SID TO BETTER DEFINE THE DEP PROC AND WHEN TO MAKE THE TURN WITHIN THE WRITTEN TEXT. SUPPLEMENTAL INFO FROM ACN 403830: THERE WAS NO DANGER; BUT WE MAY HAVE CAUSED A NOISE PROB ON THE GND. DURING PREFLT WE HAD LINE SELECTED THE BNE 8A DEP; BUT THE FO; IN AN EFFORT TO VERIFY THE IDENT OF THE 08.5 BT WAYPOINT; MAY HAVE THEN DELETED THE CGN AND OR CGN 1.5 WAYPOINTS. ON THE END OF THE RWY; SEEING THE MAGENTA LINE TURN RIGHT NEAR THE DEP END OF THE RWY; I ASKED IF THERE WAS ANY REASON TO FLY STRAIGHT AHEAD FOR A WAYS BEFORE TURNING; BUT HE CHECKED; AND NOT SEEING A RWY HDG INSTRUCTION; WE MADE THE MISTAKE OF FOLLOWING AN LNAV TRACK WITHOUT A RAW DATA BACKUP. ALSO; AFTER TRYING TO IDENT THE DEP WAYPOINTS; WE SHOULD HAVE RESELECTED THE SID TO PROTECT AGAINST AN INADVERTENT CHANGE LIKE HE MUST HAVE MADE. NAV ERROR.