Clocks in motion run slower than those at rest. The on-board time of a satellite differs therefore from that of the receiver on Earth. Depending on the satellite's velocity, one would have a navigation error of the order of two kilometres per day without considering this effect of Special Relativity.

The satellites of the Global Positioning System (GPS) move at a speed of about 3,875 metres per second, whereas a stationary receiver at the equator moves as a consequence of Earth's rotation with a speed of 463 metres per second, but rests at the pole. The relativistic error is thus rather independent of the movement of a normal GPS receiver at the surface.