Pilotage's the use of fixed visual references on the ground or sea by means of sight or radar to guide oneself to a destination, sometimes with the help of a map or nautical chart. People use pilotage for activities such as guiding vessels and aircraft, hiking and Scuba diving. When visual references aren't available, it's necessary to use an alternative method of navigation such as dead reckoning (typically with a compass), radio navigation, and satellite navigation (such as GPS). Difficulties… (More on Pilotage)