In relativity theory the advance of an atomic clock in a GPS satellite of some38 microseconds in 24 hours is explained by time dilation because of velocity from the Special Relativity Theory and time dilation in a gravitational field from the General Relativity Theory. The article shows that the time advance of a GPS satellite can be explained without any relativity theory and the formulas are in the first order the same as inthe relativity theory. It is also shown that the calculation of the GPS clock advance from the relativity theory is incorrectly made: in relativity theory there is the equivalence principle and because of it, the time dilation caused by acceleration due to the curved orbitmust be included. When it is included, the clock advance is incorrect. It is also shown thatEinstein's 1907 calculation of the gravitational redshift is incorrectly made, though theresult is correct.