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Originally Posted by kovidgoyal
@pricew: Actually, you don't have to shield planes from all devices or even test each plane with every device. What you need is to establish a set of standards about the electromagnetic radiation permissible from electronic devices. In the US, the FCC already does this. The problem is that the FCC standards are incompatible with similar (though more rigorous) standards setup by the FAA.
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One problem with this is that FCC testing is far from perfect. For example, emissions from electronic equipment are very dependent on what that equipment is doing at the time. For example, the radiation from a laptop, or electronic reader, or anything that involves a processor executing code (which is pretty much everything these days), depends on the software being run. Manufacturers tend not to repeat EMC tests on their kit every time they release a new version of firmware. (Perhaps that's paranoid, but over-caution seems a sensible starting point where planes are concerned).
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And you really don't need to worry about random circuit boards becoming antennae. It's very simple to shield circuitry from EM radiation. Just put it behind metal.
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The trouble is, any useful piece of equipment needs to interact with its surroundings - it needs inputs and outputs. These necessitate holes in any metal shield. If you look at the radiated emissions from typical equipment, most of it will be leaking out through network connections, keyboard cables, mains power connections etc. The same is true of sensitivity to EMI - each of these interfaces allows an entry point for incoming emissions.
/JB