@sensor. To make pitots independent of air density in the 0.3<M<1 range, the formula used is (with a lots more brackets in both forumula) M=sqrt((2/G-1)(Pstag/Pstatic)^(G-1/G)-1)). This then takes the Pstag and Pstatic and calculates M via gamma G. Hence why my point that a variation in the G assumption leads to incorrect calculations. (But measured Pstatic is wrong due to sensor location so this value is then recalibrated from the measured M etc etc.) If TAT and SAT are measured (rather than SAT calculated from TAT using M from pitot calculation) then this can be done via M=sqrt((TAT/SAT-1)(2/G-1)). Again using G rather than having to know density. Assuming Gamma is constant takes away the density problem. But is this assumption valid in a Cb
