GPS readings: why is altitude inaccurate by 50m, while longitude and latitude are more precise? I'm using the GeoTracker application to record position and velocity as I exercise along a track. I live on relatively flat ground, only shift up and down no more than5 meters at the very maximum, but while latitude and longitude readings seem quite precise, the program, which uses GPS (and IMHO does not use the pressure sensors / barometer to determine altitude) reports the difference between maximum and minimum altitude along the track to be about 50m. This is quite inaccurate it seems. Why is this?

Thanks.
It's likely due to the fact that GPS is simply not very well suited for getting precise altitude measurements, and never has been. Certainly not typical consumer-grade chips. Garmin suggests that variances of up to 400 feet are to be expected in their devices, for example. It's just a geometry problem.

With that in mind, I would doubt that Android has much of a meaningful impact here. Any GPS device will struggle to get a particularly accurate altitude reading. I suppose some apps may appear to be "more precise" than others by taking windowed averages of the altitude data or something (rather than directly surfacing the raw data to the user) but they'll all be getting the same values from the GPS chip.