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You Don’t Need to Use Airplane Mode on Airplanes
(gizmodo.com)
This is a most excellent place for technology news and articles.
I put my phone in airplane mode if for no other reason than if it's constantly trying to connect to a signal or Wi-Fi, it drains the battery way faster.
Or that. Whatever the reason is, if one is being asked to disable phone, then disable it. There's no reason to be an smartass and cause issues.