Flat Earth. the "Globe Earth Society" and it's never ending Cult of lying thieves.

The bubble level app for Android and iOS both work based on the same science. One person can be checking the altitude, while the other checks to see if their vector for down ever changes. Whenever the plane hits turbulence and the plane tilts to either side, the bubble level app will reflect it. It will also reflect it on landing, the same as the altimeter apps will. Just to shut down the fuckery, one could take an actual bubble level with them to confirm if the app is working properly.