Ground speed: GPS coordinates
Indicated air speed: The most common way is a pitot-static system. The plane will have one or more “static ports” with calm air from outside and one or more “pitot tubes” where outside air comes rushing into a chamber at full speed, creating a pocket of higher pressure. (It’s literally called “ram air pressure” because the air is ramming itself in.) Using the difference between static air pressure and ram air pressure, the plane’s computers can calculate the speed of the ram air – which is also the plane’s air speed.
Latest Answers