Originally Posted by Rivet gun
Perhaps I need to explain compressibility error.
Yes, perhaps you do!
The difference between CAS and EAS is due to the density of the air through which you are flying. Air density is not a "compressibility effect", so I find it surprising that you are proposing to call it "compressibility error".
Below about Mach 0.3, s far as I known there are no (or few) compressibility effects worth noting for aerodynamicists*. Above Mach 0.3 (very roughly speaking), the "compressibility effects" consist (roughly speaking) of a correction factor which is an algebraic function of Mach number.
*Mad (Flt) Scientist has told of an airplane at which compressibility effects begin to be felt at about Mach 0.2.
PBL