The compass rose is a well-known feature for those who fly or pilot aircraft and is an integral part of nearly every navigational system, including aeronautical, nautical, and global positioning systems. It can be found at most general aviation airports, where it is used to calibrate an aircraft's magnetic compass. In the early days of flying, before radio navigational aids, the compass was the most important instrument a pilot could use for navigation. Before flight, the pilot had to align the compass to magnetic north, and a compass rose allowed the pilot to calibrate the compass by lining up the aircraft on the north-pointing axis. A compass rose shows both true north and magnetic north: true north is the geographic location of the North Pole, while magnetic north is the direction toward which the north pole of a magnetic object, such as a compass, points.