Indicated airspeed measures the dynamic pressure exerted on the aircraft by the motion of the surrounding fluid, not the velocity relative to the ground. Airspe

Indicated airspeed measures the dynamic pressure exerted on the aircraft by the motion of the surrounding fluid, not the velocity relative to the ground. Airspeed indicators are calibrated at sea level so you need more information in order to get the calibrated airspeed for your altitude and you still need more data + error correction to turn that into true airspeed, which is the actual velocity of the plane relative to the air.