MLG ACFT ON OCEANIC AIRWAY DEVIATED FOR WX; BUT RPTR CAPT AND FO FAULT THE AIRWAY NAV CHART. CTLR INTERVENED TELLING THEM THEY WERE 15 MI OFF COURSE AND THEY CORRECTED BACK.

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WE WERE INFORMED THAT WE WERE 15 MI SE OF COURSE AT THE ABOVE MENTIONED AREA BY HAVANA CTR. THIS OCCURRED BECAUSE IF YOU LOOK AT THE COMMERCIAL CHART (LA(HIL)3); THE RADIAL OUT OF COZUMEL VOR IS 048 DEGS; THEN AFTER NUKAN INTXN; THERE IS WHAT APPEARS TO BE AN AZIMUTH CHANGE TO 051 DEGS. THIS AZIMUTH CHANGE CAUSED OUR BEING THE ALLEGED 15 MI SE OFF COURSE. ALSO; A CONTRIBUTING FACTORS WAS THE GREAT TSTM ACTIVITY IN THE AREA OF OCCURRENCE. THE 051 DEG AZIMUTH TRACK WAS KEEPING US AWAY FROM A CELL; WHEREAS THE 048 DEG TRACK WOULD HAVE PUT US IN THE CELL. BUT ULTIMATELY; THE 051 DEG DEPICTION JUST AFTER NUKAN INTXN WAS THE CHIEF CAUSE OF THIS DEV. WE CERTAINLY WOULD HAVE REQUESTED A DEV R OF COURSE TO AVOID THE CELL ACTIVITY. (ALSO; 15 MI SEEMS TO BE MORE THAN WHAT WE WERE OFF COURSE IN REALITY.) WE THEN WERE TOLD OF THE PROB; WE WERE ABLE TO CORRECT L BECAUSE THE CELL WAS NOW BEHIND US. WE APOLOGIZED AND WENT TO THE 048 DEG RADIAL. BY THIS TIME; KEY WEST VOR WAS STARTING TO BE USABLE AND WAS USED TO VERIFY WHAT WAS ON COURSE.