Selfin,
I am not sure I understand your question entirely...
IAS gets its reading from the pitot tube but as TAS is increased so does the error in the IAS reading .. If you subtract that error from IAS you get EAS!
Maybe your point is about the air, thought of being incompressible at lower speeds and compressible at higher?
Last edited by Jetpipe.; 17th Oct 2012 at 10:02.