> The correction is veeeeery small. Indeed it is. The only place I can think where such a small correction matters is in the GPS system. The accuracy of the GP

> The correction is veeeeery small. Indeed it is. The only place I can think where such a small correction matters is in the GPS system. The accuracy of the GPS system depends on tracking down and eliminating every possible source of error, and to maximize position accuracy, two relativistic effects are accounted for: 1. The time dilation caused by the satellites' velocity, from Special Relativity. 2. The rate of time passage at orbital altitude compared to that at the surface, which reflects the gravitational well effect of General Relativity. The two effects move in opposite directions, but they don't cancel out. The applied correction (to the orbiting clocks) is very small indeed, but enough to avoid a gradual but serious decline in positional accuracy over time.