Modern aircraft
As in all planes since the Wright bros.
Its bad when society starts to promote an urban myth into a state where people firmly believe in it, its very bad when government organizations also accept myth as fact.
For instance, there are still a slew of signs at gas stations asking you to actually turn off your cellphone when filling. I mean, who does that these days? I have seen people texting while filling up their tank, and there are probably 4 other devices in the car powered up and transmitting or received radio waves. Devices simply do not "spark", and even if they did, I think the Mythbusters debunked this urban myth a long time ago.
While I appreciate safety regulations in planes, it was annoying in the past to have to turn off my "Discman" back in the day because of fear it might crash the plane. I mean what kind of crappy engineering has to go into a plane where a CD player could bring it down?
Also radio frequencies have been regulated almost since the time they first started being transmitted so there was no reason to ever assume that a cell or wifi transmitter on a commercial phone, tablet or computer would interfere with the industrial communication frequencies used to by the plane. Also the receivers of plane communications are on the outside of the plane, outside a big metal shell which actually makes it very difficult for signals to get in or out, hence why the receivers are on the outside.
Also "interference" is a good scapegoat for why a plane crashed when they can't find anything wrong with the the operation of the plane or its pilots. I mean think there are a lot more cases where you can't look at a tangled pile of scrap metal and have definitive proof of some mechanical failure, so I do firmly believe "interference" is used in those case where they can't prove any other problem. Its convenient and the public are willing to accept that excuse because of the long standing urban myth.
Finally since the time they pretty much discovered electricity and radio waves, they have known that a simple metal mesh can disrupt electromagnetic transmission, so there was no reason why cockpits were never protected and isolated from external transmissions ever in the history of modern commercial air travel. How is it possible that planes don't use shielded wires and isolate important electrical systems? Planes can get hit by lightning and they do not fall out of the sky, yet some kid's Nintendo 3DS has to be turned off during flight?
So its good that a government organization is actually reacting to scientific fact rather than overreacting to urban myths.