iOS Disregards Airplane Mode Setting on Reboot

I’m using an iPhone 11 Pro on iOS 14, but I have also observed this behavior on iOS 13 as well as on an iPad running iOS 14.

Sometimes, when I go to reboot my phone I will close all apps (just to cleanup the app drawer, I’m not trying to manage what’s running myself) and then put the phone into airplane mode so that it will be in airplane mode when it eventually reboots.

What I’ve noticed is that about half the time, after closing all apps and putting the phone into airplane mode, when the phone reboots, LTE is active, wifi is not connected, and the last few apps that I closed are in the app switcher. If I do it again, it works as expected. I also notice that if I wait for 30-60 seconds after closing everything, and then reboot, I almost never see this behavior.

This is more of a curiosity than anything but I wanted to see if there was a reason for this? Does iOS not immediately store the open apps and airplane mode status when set?

Thanks!

This is by design.

I've tested this on several iOS devices of various iOS versions (iOS 9, 13, 14 and iPadOS 14) and all do the same thing.

I haven't found anything that specifically says so, but it makes sense so that if it's ever lost/stolen while in Airplane mode (WiFi/Bluetooth/Cellular off) when it comes back on after a period of time, it will automatically turn things on to be able to be found.

If you turn off WiFi individually, you get a message that it's "disconnecting from WiFi for 24 hours," not permanently. This is obviously to get you connected again in case you forget or the phone is lost or stolen.

It falls into a design philosophy of "fail secure" meaning if everything fails, it will fall back to a config that will allows you to find it and/or wipe it.