# Calculating lat/lon of a point

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Hello,I'm working for almost 14 days now on a problem, which I can't solve.I want to calculate the latitude/longitude of a point, which is 10 nm out of the starting point of a runway with the exact heading to the runway.Example: Frankfurt/Main (EDDF), runway 07/R has these values for the starting point (at least this is, where FSX sets your plane if you wanna start from that runway):lat = 0.873148267797151; lon = 0.148961857610546; heading = 69

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Hi, This is very easy to achieve from inside FS(9,X), see this thread:http://forums.avsim.net/dcboard.php?az=sho..._id=33879&page=And feet could be used also instead of nmiles, for a better accuracy.Just don't don't know if you can access this functions through Simconnect...Tom

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Thank you Tom for your reply.So far, if I understand that thread correctly, it's about geocalc, a payware addon? I wanna calculate it by myself, without addon. It would be a help already, if someone could say, that i.ex. Haversine formula is the right one for using with fsx. Then I would know, that the mistake must be somewhere else.About the nm or feet - of course Im using unrounded values, so it should not really matter if I use feet or nm ...SincerelyChris.

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Chris,Geocalc functions are embedded in gps.dll on both FS9 and X versions, so the are absolutely free (or at least you paid for them when bought FS :-))I cannot say more, as I really don't know what do you want to do with those LatLon calcs.Tom

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Thanx Tom.So far, the geocalc functions are not accessible for coding i.ex. with c# I assume, since they are no normal api.Greetings,Chris.

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HiI have some routines that allow me to move the user a/c n feet up/down left/right based on the current heading. It takes a starting lat/long and then calculates the new lat/long offset based on the specified position change.I plot real flight data but have found it can be slightly out. I use the routines to place the a/c on the runway at touch-down, and then apply the offset to the lat/long for the whole flight.If you think this might be useful I can post a spreadsheet that demonstrates how its done.You can simply work out how many feet in a NM if thats what your working in etc.Regards

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Chris,Perhaps you might need a more accurate runway heading. Just being off a half degree (or maybe even just a tenth,) you could end up being too far to either side of the point you're looking for.John

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Hello,BADev, that sounds very similar to what Im doing. I don't know if you can pass some of your formulas to me, would be great! You can mail them to me i.ex.!John, I think that might be a reason! I thought of that too, since I get the idea, that my formulas should be correct, so this is almost the only reason left. Specially, I do only a 1 degree-exact heading correction. If you say only half a degree or even less might cause me being off the runway, well, it could be that!Thank you guys for your reply and help!Chris.

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Chris,I did a little research using scenery decompilers for FS, and I find that FSX has runway 7R at 69.62 degrees in its scenery files.Hopefully this will give you good results. Good luck,John

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>Chris,>>I did a little research using scenery decompilers for FS, and>I find that FSX has runway 7R at 69.62 degrees in its scenery>files.>>Hopefully this will give you good results. Good luck,>>John>This will help as well as keeping the same number of significant figures in your formulas. Don't round.i.e. make sure your long/lat coordinates of point "D" are also at least 15 sig figs.

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Thanx alot for your replies!I will try my best to get the problem solved. Sincerely,CHris.

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