JFYI, at least on iOS 13, airplane mode disables only the mobile connection, while WiFi and Bluetooth remain on. This is not hidden in any way, the buttons remain active in Control Center.
I assume that only mobile signal has enough power to be considered dangerous. Maybe someone can explain what's the reasoning behind this choice.
I feel like this aligns with what "airplane" mode should be. I find it annoying when I turn on airplane mode and it disables my bluetooth and I have to re-enable it (Android X/Api 29 and below)
The reasoning is that airlines used to ban all wireless communication during flight. Now they permit Bluetooth and WiFi but still forbid cellular. The iOS behavior is calibrated to the air travel rules.
I believe iPadOS/iOS 13 by default will leave Bluetooth on while in airplane mode (likely for watches and headphones). If you turn bluetooth off while in airplane mode, it remembers that as a preference.
It's been like that for a while if you have your wifi/Bluetooth on when airplane mode is on, it will do it the same way next time you turn on airplane mode. I used that frequently on my 5S, spare 6, and iPhone X.
The reasoning was so that WF on flight, and BT/WF peripherals like AirPods, Apple Watch, and (for the iPad) the pencil, connected keyboards, and so on, can continue to work.
