Hi Marcel!
Thank you for your kind comments!
The new version of the app is in the Apple system pending review and
it has a revised preferences selection which allows qnh in millibars and
displays output in feet if desired. I also caught and squashed a rare
bug in the input picker logic.
The question of high altitude accuracy is a bit complex. The actual
sensor is the Bosch Sensortec BMP280 Barometric Sensor which is rated
as accurate to FL200. The raw pressure reading then must be converted to
altitude using an exponential equation which takes into account lapse
rate and compressibility, etc. Lapse rate does change a bit from ideal
with daily weather. The equation I use is held to be generally accurate
up to about 11 km MSL. I personally have taken the app to as high as
8000 MSL and it is usually about 50-75 feet of panel altimeter.
I also appreciate the warning about errant pilots and rapacious lawyers.
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Ira N224XS
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