Edited sentence: )  Consequently, the GPS cannot be claimed as a proof of the Einstein's theories of relativity.170): "In relative positioning, most of the relativistic effects cancel or become negligible.Instead, prior to 1990-ies, "the changes in the designated Master Control Station (MCS), which maintains the GPS master clock, were not corrected for altitude changes, which cause gravitational relativity shifts" [] (Note the date of the reference, as year 1990.Note that GPS was never designed to utilize or test the Einstein's relativity theories.Thus in his classical book GPS Satellite Surveying, Alfred Leick writes (p