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Aircraft altitude to WGS84 altitude
Hello. I have been trying to figure out how to do the following: I have aircraft flight data collected from an ADS-B receiver which contains lat, lon, and altitude, and I would like to convert the altitude to WGS84 (height above ellipsoid). After much google hunting, I have come to the conclusion that the altitude value sent over ADS-B is the same altitude that an aircraft would send to a traffic control tower (uncorrected pressure altitude, based on an altimeter): “transponders always report altitude in flight levels, that is, they report their altitude assuming the local sea-level pressure is 29.92 inHg (1013 hPa). It is up to the receiving station to correct this altitude according to the true local atmospheric pressure and thereby determine the aircraft’s MSL altitude.”
I got a pretty good explanation of how to “correct” the pressure here and get a “true height” above the Mean Sea Level. I thought that the next step would be to run vDatum and set the input to “mean sea level” and the output to “WGS84”, but it looks like it’s more complicated than that, wanting a specific vertical reference called out, such as NGVD29.
Can someone give me some guidance on how to complete the conversion? If getting a “perfect” answer is impossible, that is fine, but maybe show me the path that would get me the closest?
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