You Don’t Need to Use Airplane Mode on Airplanes | Airplane mode hasn't been necessary for nearly 20 years, but the myth persists.

I remember once when I accidentally turned on my phone during a flight instantly the plane started to plummet out of the sky. The phone slipped out of my hands and I groped for it while people and service items flailed around the cabin as the plane tumbled. Finally I slipped out of my belt and grabbed it. With only 10,000 feet of altitude to spare, I finally managed to get the phone to go into shutdown mode by holding the power button down. The plane righted itself immediately, and I slipped the phone into my pocket quietly and kept a low profile for the rest of the flight.