CAS

                                EAS                     TAS /MN

                                                                                     

                  Altitude

 

                                                                                    At constant CAS

                                                                                    As altitude increases

                                                Speed               TAS & MN increase

Or:

CAS is a measure of dynamic pressure = ˝ρV2

Where ρ = air density (decreasing in climb) and V = TAS (increasing to keep CAS constant)

LSS is constant in isothermal conditions (temperature constant)

MN = TAS/LSS = Increasing/Constant = Increasing