jacek_flying;
what I mean is why would you plan a route through an area of turbulance if it was forecast???
Airlines do not "plan a route through an area of turbulance [sic] if it was forecast".
Flight planning, whether international or domestic is not nearly that simple, CAT is not nearly that easy to predict and pilot reports enroute may or may not indicate that a selected route is satisfactory. One simply does not board tons and tons of fuel for an extended route or "just in case", simply because turbulence is "reported" or indicated on the Sig Wx charts. The industry is exceedingly experienced at determining, most of the time, where to expect turbulence and does plan around such routes. But determining precisely where, when, at what altitude and how bad turbulence is going to be is simply not possible, and experience indicates that almost all the time, significant route diversions are not necessary. Also please bear in mind that one's own airplane is up there with hundreds and hundreds of others, on crowded routes across the Pacific and Atlantic. Finally, one does not "fly around turbulence" as though it were a pothole in the road. CAT can extend for hundreds of miles - I sat in 10hrs of moderate chop coming home from Tokyo one night and along with the dozens of flights which were in our area above, below to our side, in front and behind, there was nothing any of us or ATC could do.