It uses your phones GPS, accelerometer and barometer to show you what's going on during your flight, the main metrics shown are:
* Lat/Long + location on a map (also shows your flight path so far)
* Ground speed / Altitude
* Track/VS/Mach
* G load
* Turbulece
* Bank Estimate
This isn't for professional pilots, more for something to do while you fly
You can also take a photo and have the main stats overlaid onto it, as well as included in the EXIF data
No sign up, no ads, no tracking, works entirely in flight mode
Let me know if you find it cool, cheers :)