So in our ever-digital world, we forget that these nice digital technologies have analog underpinnings. Cellular radio signals these days are digital, but that digital signal is on top of an analog signal.

iPads and other non-cellular devices have CPUs and CPUs have clocks, which an analog guy would properly identify as a Radio which is transmitting. Non-cellular devices also increasingly have Wi-fi, which is a digital technology on top of an analog radio signal. So an iPad, for example, has at least two radios.

So an all-metal airplane with on the order of a hundred folks, each with 2*n transmitting radios contains measurable radio frequency signal.

So what frequency is this radiation?

Well, in a non-linear environment (another analog deal), the result is the sum and difference of all the signals, pairwise. So can an analog-enlignened person honestly say that this mash of radio-frequency energy does not expose the cockpit avionics to possible spurious signal?

If you don't think that is a potential problem, I would rather drive you in my car than fly with you.

Now regarding cellular phones, it is the FCC that issues this regulation, not the FAA. Why would they be interested in that? Well, since cellular telephone communication is line of sight, do the math on how many more cells you and your concealed cellphone are trying to capture at 1000 feet or higher? Could be an entire city's worth.

Stewardesses are not generally tested for their knowledge of RF propagation or RF interference, so focusing your anger on them is not productive.

And yes, the iPhone or droid is a marvelous piece of technology, but owning one does not make you immune to the facts of the analog world.