[mipnix]

I flew for the airlines.

The problem is not your everyday takeoff and landing. The problem arises when the weather deteriorates to near zero visibility and the crew is relying on instrumentation to find that strip of pavement, at 130 knots.

Instrument approaches rely on a narrowing volume of radio signals, the closer one is to the runway. The tighter the signal, therefore, the greater the deviation should something go wrong. Think of threading a string through a funnel, if you touch the edges, you lose. Now do it on a trampoline while someone else jumps on it. I assume we can all agree that wildly porpoising a 200k lb jet, 400 from the ground, chasing a signal, is not a good idea.

Vehicles on the ground are prevented from encroaching on the approach signal area, when aircraft are shooting approaches in reduced visibility conditions, to prevent them for interrupting the signal. In the cockpit you can see your signals fluctuate if someone does cross that threshold. It happens.

When visibility is good, it is a non event but when you can't see jack, having your guidance just start dancing around, gives one moments of pause.

The phones do interfere in some manner. TO what degree, I can't say. I have forgotten to turn my phone off before takeoff and get the annoying beep in the headset when we descend into an area with coverage, so something is going on.

The reason they ask you to turn it off is because they can't tell you its okay, because they haven't tested it. They can't say, well turn it off if it's cloudy or if the bases are below 300'. Some departures and arrivals require precise navigation, even in good weather, for traffic flow reasons. Missing a fix on departure or arrival could cause traffic alerts or aircraft deviations.

All rules exist for the worst possible scenario. Not the milk run. But how do you explain that to the traveling masses? You should be more concerned with the fact those little dixie cup oxygen masks they instruct you to put on in the event of a decompression, won't actually supply you with oxygen when the shit hits the fan at altitude. It's a partial pressure thing.

That's just between you and me...

Edit: At the end of the day, it is the law. If the crew is having a bad day and has a stick up their ass, they can make your day a lot worse. You need to ask yourself, does ignoring the rule, no matter how inane you think it is, really make a body cavity search worth checking the latest XKCD update?

[cromulent]

> But how do you explain that to the traveling masses?

I think this has a lot to do with the whole "turn every device off" thing. Keeping aggravation levels down, with tired and stressed passengers, with a large mix of cultures and languages, means that it is much easier to say: everything must be turned off. Otherwise you get into 200 discussions about which devices are allowed, and you have to verify each one.

[wglb]

Each one of these devices is a radio transmitter. Even if it is a receiver, or dvd or HP200lx. They all transmit measurable signals. If two or more are on, this can result in the sum and difference of each pair of signals.

Thus verifying each one is not going to tell the whole story.

[thewileyone]

Isn't the avionics room under the cockpit shielded to sustain operations through lightning storms, signals bouncing off the ionosphere, solar flares, etc.?

I've flown commercially with my phone left on and privately in Cessnas and I haven't experienced anything negative. My dad's a pilot too by the way and he said that there's no supporting evidence, but this is a just small rule so might as well comply.

[mipnix]

There is no supporting evidence. That is part of the problem. The FAA has enough on their hands trying to get the air traffic control system into the latter half of the twentieth century, without trying to test for every stray signal and how it might affect the navigation. A blanket policy, restricting all devices does that.

The wiring is shielded to an extent but there is no special safe room for the avionics. A lot of it is in the nose, right in front of the crew. It is, after all, a very thin tube of aluminum we are all shooting around in. Weight is something to be avoided.

[wglb]

So how do the signals get to the avionics? Let's say that there is an antenna outside the avionics room. It needs to pick up signals. All of these devices emit signals, and some of the signals will go outside the airplane to said antenna.