While my experience agrees with you regarding accuracy and stability, it's still better to know the local pressure setting, especially if landing an aircraft without a radio altimeter. Setting an altimeter based on GPS sounds quite rare to me.
On Feb 17, 2018 3:12 PM, "Poutnik" <[email protected]> wrote: > As being trained in past as the military meteorologist, in pre-GPS era, I > am aware of that. But the offset value is bigger than GPS accuracy of the > static value averaged. BTW, the most handy way how to calibrate the > barometric altimeter at unknown altitude is the GPS device. While > barometric altimeters have superior short-term accuracy and stability, GPS > devices have superior long-term accuracy and stability. Fortunately, for > most personal usage, absolute altitudes are not that important, rather the > relative changes. > > Dne 17/02/2018 v 23:35 Robert Grant napsal(a): > > I'm pretty sure that none of the devices listed by the op use barometric > altimeters; even the Garmin Glo is GPS altimetry. GPS is known for its > lack of precision in determining altitude. In aviation, old school > barometric altimeters are still the gold standard, but they require > periodic barometric pressure adjustment. While GPS is great for navigating > around the earth, it would be very foolish to use GPS altitude for landing > an aircraft. Bottom line: don't expect any phone with only GPS altitude > to agree precisely with a database supplied measurement. > > > <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail&utm_term=icon> > Virus-free. > www.avast.com > <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail&utm_term=link> > > On Sat, Feb 17, 2018 at 1:41 PM, Harry van der Wolf <[email protected]> > wrote: > >> >> >> 2018-02-17 19:41 GMT+01:00 Poutnik <[email protected]>: >>> >>> >>> While Europe subtracts altitude by the correction, >>> US adds altitude, so the higher value is the (over?)corrected one. >>> >>> >> I didn't know that :) >> > > -- > Poutnik ( The Wanderer ) > > My Brouter profiles https://github.com/poutnikl/Brouter-profiles/wiki > > -- > You received this message because you are subscribed to the Google Groups > "Osmand" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "Osmand" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
