I understand that current iPhones navigation apps rely heavily, if not primarily, if not exclusively on the barometric pressure rather than GPS to determine the elevation / altitude of the phone. Without calibrating the barometer to the actual elevation, this means the indicated elevation will not be accurate.

I have tried several apps and all seem to agree, from moment to moment, what is the elevation, but all routinely drift over a range > 100' for a single, fixed location. One, My Altitude, simultaneously shows a claimed elevation and the barometric pressure, and I can see the indicated elevation change in lockstep with indicated changes of pressure.

I understand that years ago the elevation was determined strictly by the iPhone's internal GPS, but then people got the bright idea to use the barometer function to reduce power consumption. Perhaps that is a noble cause, but not if one needs accuracy.

Before anyone seeks to educate me, I know that there are inevitable errors for GPS applications and some drift without differential GPS corrections.

Anyway, does anyone know of an app in which it is possible to turn off the barometer input for the determination of elevation?

Thanks.