How does high altitude affect air speed indication?

At high altitudes, the air density decreases, which influences how airspeed is measured. Airspeed indicators, which are typically calibrated to the standard atmosphere, rely on the pressure difference between static and dynamic pressure. As altitude increases, the reduced air density results in a lower dynamic pressure for a given airflow around the aircraft. This can lead to a lower airspeed reading than what is actually being experienced.

Since the airspeed indicator does not account for the reduced density at higher altitudes, it can falsely indicate a slower airspeed. Therefore, pilots must be aware that the airspeed reading can be misleading in such conditions, reinforcing the need for careful consideration of flight parameters at altitude.