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Old 4th Nov 2015, 12:05
  #819 (permalink)  
Icarus2001
 
Join Date: Dec 2001
Location: Brisvegas
Posts: 2,767
Ka-2B pilot

GPS is as accurate in altitude as it is in Lat/Long.
No it isn't.

If you fly gliders I can assume you know the difference between height, altitude and pressure altitude.

A GPS altitude is expressed above what datum? Think about it for a minute.

The earth is not round, it is an oblate spheroid. GPS altitude is measured above a geometric model of the earth. In some places the surface of this model is above the "real" sea level surface and in some places below the "real" surface. WGS 84 is one such model etc

I fly gliders and use GPS for height readings and it is extremely accurate, much more so than a barometric altimeter!
Perhaps you do but no it isn't.

Here is a link to a useful article on the subject with good diagrams.

GPS and altitude for hang gliding and paragliding | Cross Country Magazine

Have a read and a think.

As I said earlier, the FR24 data is almost useless.
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