Hello all.At first sorry for my english.I'm writting because I have a little problem with 747-400 QUEEN ...When I'm preparing my flightplan, I enter all the needing datas into the FMC.After I switch on LNAV, VNAV.Until now, there are no problems.Then, during the flight my plane has difficulties to follow its track.The plane goes to the next waypoints and, as normal, it reaches this waypoints.But, to reach the waypoints, the plane doesn't exactly follow the good track.The ATC must remind me to turn in order to reach the good track.(But there are no pbs with fmc).If possible,I'd like to know why my plane leaves the track while LNAV is switched.Thank you for your answer.Thomas.:-)

Thomas, after inputting your flight plan into the FMC and executing it have you cheded to see if there are any route discontinuities? You would be able to find them on the LEGS page. I always make a sanity check of the LEGS page to see if I have any.

Thomas,Are you sure you're loading exactly the same flightplan into FS as you are the 744 FMC? Sometimes if FS's ATC thinks you should be somewhere other than what's programmed into the FMC (this can happen if you're using SIDs or STARs etc...) then it's gonna tell you you're off course or whatever. If this is the case then it's just a limitation of the FS ATC system. Use Radar Contact or VATSIM if you want better ATC.

Thank you for answering.Yes, I always check if there are flightplan discontinuities. So that is not the problem I think.Then, I often use SIDs and STARs. I'm actually flighting from NY Kennedy to Jeddah, and I usued SIDs.I'm gonna have a look at VATSIM.Thank you very much.