Variometer is a professional flight instrument developed specific for the iPad and the iPhone.
The variometer is an instrument that indicates the current velocity speed (speed up and down) of the aircraft (it will also work excellent to measure the speed of an elevator :)).
This app has support for a Bluetooth sensor unit named NODE with a Clima sensor from variabletech. With this hardware, the instrument will use the real measured pressure to calculate altitude and speed – the same way as a real instrument.
If you don’t have a NODE with Clima module, the app uses the internal GPS chip instead. The app will have the same functionality without a NODE but with a little less accuracy (observe that the iPad Wifi and iPod Touch have a simpler and less accurate GPS chip).