If there was ever a shade of a possibility that a cellphone or other electronic device could interfere with the operation of an aircraft, they'd never even let

If there was ever a shade of a possibility that a cellphone or other electronic device could interfere with the operation of an aircraft, they'd never even let you take anything like that onboard. The whole "turn off your devices" thing is more about validating compliance and making people pay attention during the most incident-prone times of flight (takeoff and landing)