CONFUSING FORMAT OF FILED AND REVISED ROUTE SEGMENTS ON PDC CONTRIBUTES TO TRACK DEV AND CFTT FOR B757-200.

Narrative

OUR PDC STATED: SEA MWH...MOUNTAIN 5 DEP; MAINTAIN 9000 FT. PDC ALSO STATED 'REVISED SEGMENT 'SEA J90 MWH.' AT GATE; REVISED SEGMENT WAS LOADED INTO FMC RTE. THE MOUNTAIN 5 DEP/FIX DROPPED OUT. WE FAILED TO RESELECT IT. AFTER LIFTOFF; AS TWR WAS BUSY TALKING TO OTHER ACFT; WE WERE NOT HANDED OFF TO DEP CTL. I QUERIED TWR IF THEY WANTED US TO SWITCH TO DEP. THEY SAID YES. AFTER LIFTOFF; AT 400 FT; I-NAV WAS SELECTED AND ACFT WAS HAND FLOWN. FO BEGAN L TURN TO JOIN J90 MWH. I SAID TO FO THAT OUR TURN/COURSE TO THE L DID NOT LOOK CORRECT. HE SHALLOWED BANK/TURN. I DIALED UP DEP FREQ; CHKED IN WITH 'ACFT X; CLBING 9000 FT; CONFIRM OUR ROUTING.' DEP ASKED IF WE WERE GIVEN HDG BY TWR. I SAID NO. DEP THEN INSTRUCTED US TO TURN R 160 DEGS (WE HAD MADE THE TURN TO ABOUT 120 DEGS BY THIS TIME). WE TURNED TO 160 DEGS; BROKE OUT ON TOP ABOUT 3500 FT MSL; AND VISUALLY OBSERVED MT RAINIER TO OUR R. SHORTLY AFTER BEING STEADY ON 160 DEG HDG; DEP CLRED US 'FLY 060 DEGS; DIRECT MWH; ON COURSE.' WE DID; AND RECEIVED NO FURTHER COMMENTS FROM DEP; AND WAS HANDED OFF TO CTR. ABOUT 30 MINS LATER; CTR SAID THAT SEA TRACON WANTED US TO CALL THEM ABOUT POSSIBLE RTE DEV. I CALLED WHEN ARRIVING AT DEST; DISCUSSED ALL ASPECTS WITH A TRACON SUPVR. WE BOTH UNDERSTOOD WHAT HAD OCCURRED. THEY TOLD ME THAT 'NOTHING ELSE WILL COME OF IT.' MAY I SUGGEST THAT IT WOULD BE BEST IF OUR DISPATCHERS WOULD FILE ROUTINGS THE SAME AS THE DEP'S/CTR'S COMPUTERS LIKE ROUTINGS TO BE FILED. THIS WILL AVOID 'REVISED SEGMENT' ON PDC; WHICH WOULD DECREASE PLT WORKLOAD AND THE CHANCE FOR FMC ROUTING ERRORS.