The GPS system needs a small but important correction due to Special and General relativity.<p>From: <a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Global_Positioning_System" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Global_Positioning_System</a><p>&gt; <i>Special and general relativity predict that the clocks on the GPS satellites would be seen by the Earth&#x27;s observers to run 38 microseconds faster per day than the clocks on the Earth. The GPS calculated positions would quickly drift into error, accumulating to 10 kilometers per day. The relativistic time effect of the GPS clocks running faster than the clocks on earth was corrected for in the design of GPS.</i><p>More details: <a href="http:&#x2F;&#x2F;www.astronomy.ohio-state.edu&#x2F;~pogge&#x2F;Ast162&#x2F;Unit5&#x2F;gps.html" rel="nofollow">http:&#x2F;&#x2F;www.astronomy.ohio-state.edu&#x2F;~pogge&#x2F;Ast162&#x2F;Unit5&#x2F;gps....</a>