A change in temperature does not change pitot
(P) or static (S) pressures and MN = (P – S)/S so MN is constant.
Furthermore:
CAS is a measure of dynamic pressure = ½ρV2
Where ρ = air density (increasing as temperature decreases) and V =
TAS (decreasing to keep CAS
constant)
Also:
TAS = MN x LSS = Constant x Decreasing = Decreasing.