Modern aircraft use many additional methods of
navigation. The pilot plots his course on a flight plan
before he takes off. After take-off, an altimeter tells his
height or 'altitude' above the ground or water.
Instruments controlled by gyroscopes show whether he
is climbing or turning. Another instrument informs him
of 'drift' from his chosen course. An automatic pilot can
navigate the plane while he rests. Satellites in orbit
around the Earth give him information about the
weather and his position. When he lands, radio
beacons guide him down to the runway.