This is a plugin for the app AFTrack to handle the connection to the BlueFlyVario hardware and make use of the air pressure for an altitude replacement.
Hardware web site http://www.blueflyvario.com/
To start with you will need AFTrack and the hardware.
To use the plugin values in AFTrack select the 'Use Pressure' option in gps settings. Here you can also set up a start altitude or a fixed reference station. The pressure is shown in the satellite view. Altitude and vario values are visible in dock or big view.