Tag Archives: TAS

If an aircraft maintaining a constant CAS and flight level is flying from a warm air mass into colder air:

A: Mach number increases.
B: TAS increases.
C: TAS decreases.
D: Mach number decreases.









Answer: C



TAS is true airspeed
EAS is equivalent airspeed
ρ0 is the air density at standard sea level (1.225 kg/m3)
ρ is the density of the air in which the aircraft is flying

If you fly into a colder airmass,  ‘ρ’ will increase.

If  ‘ρ’ increases the whole square root side of the equation will decrease.

If EAS (or CAS calibrated for instrument/ position / density error) remains the same,

then TAS will decrease.