B757 CREW HAD TRACK DEV.

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FLT X; B737-800. ON GND IN BERMUDA FLT RTE WAS LOADED INTO FMC VIA DATALINK FROM COMPANY DISPATCH. CREW VIEWED RTE ON RTE AND LEGS PAGES OF FMC AND ACCEPTED THE RTE AS XMITTED BY COMPANY. BERMUDA CLRNC CTL WAS CONTACTED AND CLRNC 'AS FILED' WAS ISSUED. CREW ASSUMED RTE XMITTED BY DISPATCH WAS FILED RTE. ONCE AIRBORNE; CREW WAS SWITCHED FROM ZNY TO COMMERCIAL RADIO AND TOLD TO RPT TARGA. AT TARGA CREW CHKED IN WITH COMMERCIAL RADIO AND PASSED THE FOLLOWING RPT: 'TARGA; TIME XXXX; FL350; BERGH; TIME XXXX; OWENZ NEXT.' COMMERCIAL RADIO THEN ASKED; 'DO YOU HAVE AN ESTIMATE FOR FLANN?' CREW REPLIED 'IT IS NOT ON OUR RTE...DO YOU NEED US OVER FLANN?' COMMERCIAL RADIO SAID 'STAND BY.' AFTER A COUPLE OF MINS; COMMERCIAL RADIO RETURNED TO FREQ AND SAID TO '...RPT ABEAM FLANN.' CREW CONTINUED WITH FLT FROM TARGA DIRECT BERGH. UPON CONTACT WITH ZNY AGAIN ABEAM FLANN; CREW WAS INFORMED THEY HAD DEVIATED FROM FILED COURSE AND A COURSE DEV WAS BEING RPTED. COMPANY COURSE IN FMC WAS OBVIOUSLY WRONG. HOWEVER; THIS ERROR COULD HAVE BEEN CORRECTED AT TARGA WHEN CREW ASKED ATC IF A RPT OVER FLANN WAS DESIRED. WHEN ATC RESPONDED 'JUST RPT ABEAM FLANN' CREW HAD NOT YET DEVIATED FROM COURSE. UPON RECEIPT OF INSTRUCTIONS FROM ATC TO RPT 'ABEAM FLANN' CREW ASSUMED RTE IN FMC WAS CORRECT. ATC WAS AWARE OF ACFT POS AT ALL TIMES.