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chumley

True or magnetic?

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Are the wind speeds displayed in the FMC and navigation displays true or magnetic?Andy b

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The FD winds are definitely magnetic. I'm not sure about the FMC, however. Anyone?Roger Precious

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Captains-the winds displayed on the ND are magnetic.the winds displayed on the FMC are true.Hope that helps.

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"the winds displayed on the ND are magnetic."Hi, Lefteris...Didn't we say that the winds are relative to whatever reference the ND was showing at the time? E.g. if you were flying in polar latitudes and the ND was showing TRUE, the winds would also show true.Or am I confused again? :-)Cheers.Ian.

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>the winds displayed on the FMC are true.Do I have to enter any wind in true heading in the FMC (e. g. wind forecasts for descend planning)? IMHO navigation is based mainly on magnetic heading.Tom.

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Ian-yes, indeed, but at the moment the ND does not have a TRU/MAG switch for polar routes... (a LOT more work, for something that FS itself can't really cope with either). As such, my reply stands (the ND winds are magnetic ;-) ).Cheers,

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"yes, indeed, but at the moment the ND does not have a TRU/MAG switch for polar routes... (a LOT more work, for something that FS itself can't really cope with either). As such, my reply stands (the ND winds are magnetic )."Does this mean that you're planning to implement this later???Would be great!E. Fritz

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"yes, indeed, but at the moment the ND does not have a TRU/MAG switch for polar routes... "Ah, that explains it... So PMDG doesn't even autoswitch at the appropriate latitude/longitude? ( I'm not a big fan of cold weather, so I can't say I've ventured that far north/south in the sim ;-)).I have the feeling you've told me this before... Sorry (Or was it Wade Chafe commenting on 767 PIC, I forget?).Cheers.Ian.

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Hi Tom,The NG manual I have says that these wind inputs should be true. Navigation is indeed mostly based on magnetic heading rather than true, but to get back to the basics of navigation:TrueTrack plus or minus Wind/Velocity = TrueHeadingTrueHeading - variation = MagneticHeadingMagneticHeading - deviation = CompassHeadingis one of things I had to learn for my PPL and it still holds true for the heavy iron: you first apply the true W/V correction and then the variation.Now the question is of course where do we get our forecasts and do they have true or magnetic winds!Leo BakkerPS. Just to make sure: in real life, surface winds are always given in magnetic, so they make sense in relation to the magnetic runway heading. Again, don't know exactly what FS's ATIS does.

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I got the impression that he was trying to tell us that he was NOT going to implement it. To be quite honest, I don't know how much sense it would make to do that. Or maybe it would be different for the BBJ, with its long range capability?For the Classic I think I have seen a manual where the aircraft was simply not allowed to go above 73 N or below 60 S. So putting a placard on the main panel bitmap would do the trick (sorry, just teasing :-) )Leo Bakker

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Ian-yes, I have, in some alphabet letter discussion list... ;-)

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Yes it did. The thread got lost and I have only just come back to it.Thanks.Andy b

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