Passage planning begins with laying out a route along a chart, which comprises a series of courses between fixes—verifiable locations that confirm the actual track of the ship on the ocean. Once a course has been set, the person at the helm attempts to follow its direction with reference to the compass. The navigator notes the time and speed at each fix to estimate the arrival at the next fix, a process called dead reckoning. For coast-wise navigation, sightings from known landmarks or navigational aids may be used to establish fixes, a process called pilotage. At sea, sailing ships used celestial navigation on a daily schedule, as follows: