The airspeed indicator or airspeed gauge is an instrument used in an aircraft to display the craft’s airspeed, typically in knots, to the pilot. The Airspeed Indicators shows the aircraft’s speed (usually in knots) relative to the surrounding air. It works by measuring the ram-air pressure in the aircraft’s pitot tube. The indicated airspeed must be corrected for air density (which varies with altitude, temperature and humidity) in …