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# GeoCalcAzimuth 1/2 -- DME

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Has any one used the GeoCalcAzimuth inputs For a Geo Calc? If I understand this correctly, I would have to do a geocalc first to get distance/heading then do another geocalc with LAT/LON/AZI as input again. Is this correct? And if so, would the inputs would be the bearing from the station? What would be the second azimuth input? I'm testing a "virtual DME3" and as the distance gets larger the error gets larger between the radio DME and the virtual DME. ( 0.4 NM @ 80NM @ FL250 ) I figure this has to do with the curve of the earth. At these larger distances the V/DME gets closer to the GPS distance than the Radio DME distances. For my distance i'm using the following -slant distance = GeoCalcDistance sqr AltitudeASL StationASL - abs sqr + sqrt Is this correction even worth pusuing? TIA for any input.Roman

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Hi Roman,Here you have an example on how to use Azimuth calcs. http://forums.avsim.net/dcboard.php?az=sho...ing_type=searchIn short it is used to find the coordinates of a given point that is n miles and with a d bearing from your aircraft (or any other point with known position)You could try this formula as well:slant (hypotenuse) = (Geocalcdistance,nmiles) sqr (Altitude,nmiles) sqr + sqrtAnd AFAIK this value should be similar to the DME reading in your NAV radio.Tom

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Tom, Thanx for that link, should have searched first :-erks :-bang. My formula is the same as yours except it's the difference between station alt and plane alt, units are in NMiles. That link is bookmarked.. After this little project I'm hoping to make a Bendix/King KNs-80 RNAV unit so that link will help considerably.The error distance i'll just have to live with.Roman

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