Minimize data usage in the air
 

Sorry if this had been asked before but what's the best way to minimize data usage either Android (one plus) or windows 10. Last time I bought a data package it ran out on a matter of minutes without me doing anything. I just want to turn off all background data so it only uses data on the app I'm on. Thanks.

On Android you could turn off background data in each app. On my Pixel phone, it is under Mobile Data Usage in the Network menu.

In Win10 you can click the network icon by the clock, choose the wifi network in question, click Properties, and turn on the Metered Connection slider.

You can also set wifi networks as metered in Android: connect to the wifi, go into settings for that network, hit 'advanced' then 'network usage' and select 'treat as metered' and it'll treat that network the same as mobile data for update and background data purposes.

Apps that aren't misbehaving should use very little background data on the mobile network or a metered wifi.

For others reading this thread in the future:
On iPhone there is a low-data mode in iOS 13 which I believe does the same thing.
go to wifi, select the (i) button for information... then enable "low data mode" for the plane's wifi.

Another option is to just plain fly United. You won't have data connectivity consistently enough to "waste" data.