Note: See follow-up item.
My answer is No. Of course not. The rule is pure theater.
Or, Yes, A Little Bit, But Not For The Reasons They Say.
Why do I think there is no "real" danger that Blackberries, Kindles and nooks, iPhones and iPads, Bose/Sony headsets, handheld GPS devices, or any other "equipment with an off/on switches" will interfere with navigation equipment, safe approaches and landing, and overall welfare? Because:
- 100% of the pilots making those landings and approaches have GPS receivers right there next to them in the cockpits, of the kind you would have to turn off if you had one in your lap in seat 38F;
- Every one of the airline pilots I've ever asked has kept his or her cell phone turned on in the cockpit, again right next to the "sensitive" equipment. I always had a cell phone with me, turned on, during flights in small planes, and several times I've used it in flight. (Once, to contact a control tower when my radio had failed; another time, to get an IFR clearance when there were radio problems.)
- Many of those pilots, depending on the type of airplane, are wearing noise-cancelling headsets through the whole flight, of the sort you are made to turn off as a passenger. All small-plane pilots are wearing those headsets through the whole flight.
- More and more pilots have iPads turned on through the entire flight, including United pilots who are being switched en masse from paper to iPad navigational charts. I now use an iPad extensively when flying, because the program I use, Foreflight, is so much more adaptable and informative than the paper charts it replaced. It would make things riskier, rather than safer, if I had to turn it off at arbitrary times.
- And, on all "non-airline big-aircraft" flights, like political charters or corporate jets, people leave their "devices" on the whole time, and it never causes a problem.
- I won't even make the fish-in-a-barrel point, which is: the very fact that the cell phone/ Blackberry "ban" is never enforced shows that no one takes it seriously.
So, I will bet anyone a lot of money that no one can demonstrate a "navigational" or "safety" risk from letting people use all the equipment they want in every instant of flight. I say this even though I've gotten in big trouble with (usually United) flight staff in trying to make this point in real time.
But here is the only, admittedly weak rationale behind the "turn all equipment off" diktat. If anything went wrong on a crowded airline flight, the flight crew would need everyone's full attention, now. The prevailing theory is that passengers are less likely to be distracted if they're not cocooned by their acoustic headsets or distracted by their iPads.
My theory is that in a real airplane emergency people would pay attention no matter what else was happening -- and that the real distraction is the series of obviously phony, "security theater" warnings we have to pretend to take seriously. But I know that the chance of changing this utterly pointless rule, among other utterly pointless rules, is effectively zero. So I'll keep my cell phone, iPad, computer, GPS, and noise-cancelling headsets all switched on when I'm actually sitting in a cockpit -- and obey the (irrational) orders to switch them off when I am in seat 38F.