IMO NO they wont interfere with navs or bring a plane out of the sky. In reality if these devices coud alter an aircrafts system they would be required to be checked baggage. The FAA wouldnt allow such devices on aircraft if they had any potential to be dangerous
Yes, it is a rule and yes the rule is absurd. There have been a number of studies showing this. I follow the rules to a point. For example why can you phone be on but not your computer? To me it is about consistency and reality. The reality is the FA will get in serious trouble if they do not enforce the FAA stupidity. Therefore once the door shuts no matter how stupid the rule is I follow it. I leave my computer on until the door shuts, if I am asked to turn it off personally I do. I believe the reason of the difference between phones and computers is attention. I remember back in the early 90s I had a personal rule that I would finish my expense report on my laptop before wheels up. I am still alive to tell about it.
