Hey!! Our safety is at risk. That's why we can't bring nail files or pocket screwdrivers onto planes! (There really is a crazy out there somewhere who would try to file off a wing...)
Good cell phones may or may not be a problem. I'm sure my hearing aids aren't either, nor is your pacemaker or Harry's watch. But 'Uncle Joe, (the one who loves to 'tinker' with stuff,) made his own cell phone, and used a few wraps too many of wire and now the damn thing works like an electromagnet every time it rings! That electromagnet might just affect the plane's navi system enough to make us land in Cuba instead of Aruba. Now, if you're Canadian that isn't a problem. You're allowed to go there to buy your cigars and 161 proof rum, but we poor USAans aren't allowed to go without first getting special permission, and we most certainly can't purchase cigars while we're there.
So to eliminate problems that the Uncle Joe's of the world 'might' cause (though personally I'd love to go and do some scuba diving in Cuba) and instead of the navi system it might be the altimeter system that gets affected and we might land a minus 30 meters instead of a zero (where the ground is....)
PLEASETURNOFFYOURFREEKINE-BOOKSFORTENMINUTES! That really isn't too much to ask.
Thank you very much.
Stitchawl