...it would be off by around 11 kilometers according to the expert below.
This and more cool examples of how GPS is affected and corrected with Einstein's Relativity here
. The speaker is Christopher Hegarty, Director for Communications, Navigation and Surveillance Engineering & Spectrum at MITRE.
Also if you want to get crazy about precise measurement check out the part at here
. She is trying to measure a change in distance equal to a single part in 10,000 of the width of a proton ( a proton is around 10 to the negative 15th power of a meter).
Tom
It's too late for me to edit this but I left one part out... That 11k error is if GPS is not corrected for Relativity just for a single day.
Also interesting is that terrestrial receivers -- apparently even lowly cell-phone-grade units -- adjust the received time values for orbit eccentricity.