What change occurs to True Airspeed (TAS) at high altitudes?

At high altitudes, True Airspeed (TAS) increases primarily because of the decreasing air density. As an aircraft climbs to higher altitudes, the pressure and temperature decrease, but the indicated airspeed (IAS) may not reflect the actual speed at which the aircraft is traveling through the air mass.

TAS is the speed of an aircraft relative to the surrounding air, and it is calculated based on the indicated airspeed corrected for altitude and temperature. Given that air density decreases with altitude, a pilot must maintain a higher TAS to generate sufficient lift and keep the aircraft flying efficiently. Consequently, pilots may notice that while indicated airspeed might be lower due to less dense air, the true airspeed, which accounts for these factors, actually increases.

This effect is important for flight planning and performance calculations, as understanding TAS is crucial for ensuring safe and effective aircraft operation at varying altitudes.