Originally Posted by Telyx
Most phones use cell towers and GPS for location unless you go into Location settings and change it to use only GPS, so if you don't have a good cell signal your location accuracy might be affected by that.
I was aware of that (strong signal in both cases), and of the AGPS which I routinely update. I can't figure it out. I even restored an old ROM when I knew the GPS was good, but the performance remained poor. And it was not a fluke as now with the AT&T MVNO the GPS remains good.