How does a higher altitude affect indicated airspeed?

Indicated airspeed is the speed shown on the aircraft's airspeed indicator and is directly related to the dynamic pressure of the air flowing over the wings. At higher altitudes, the air density decreases. Since indicated airspeed relies on dynamic pressure, which depends on both air density and the square of the true airspeed, the same true airspeed results in a lower indicated airspeed at higher altitudes because there is less air density.

Therefore, as the altitude increases and air becomes less dense, the indicated airspeed actually decreases for the same true airspeed. Pilots need to understand this relationship to ensure proper performance and safety when flying at different altitudes.