You can improve the accuracy of barometric altimeters by doing the following:
Make sure the unit has a calibrated barometer. You can do this by letting the unit sit at a fixed elevation for at least half an hour with a clear view of the sky to let the elevation trend to the correct number, or manually calibrating the barometer so that the elevation is correct.
Calibrating the Barometric Altimeter Your device was already calibrated at the factory, and the device uses automatic calibration by default.
You can manually calibrate the barometric altimeter if you know the correct elevation or the correct barometric pressure.
1 Go to a location where the elevation or barometric pressure is known.
2 From your main menu Select the Setup icon - Select Altimeter - Select Calibrate Altimeter
3 Follow the on-screen instructions
If the weather is adversely affecting your altimeter (pressure is changing due to weather instead of elevation changes), you may disable it by changing the Barometer Mode setting to “fixed elevation” mode which will use GPS only for elevation data.
Barometer Mode
Variable Elevation allows the barometer to measure changes in elevation while you are moving. Fixed Elevation assumes the device is stationary at a fixed elevation, so the barometric pressure should only change due to weather.
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