Hey folks, let's not overdo the safety aspects here, so no one panics
if aboard an airliner and sees someone using a radio. I doubt any
device emitting small RF will be able to make comm reception
unreadable. Even if it did, there are then fallback procedures which
the pilot is required to know by heart, and the pilot is even
permitted to continue flight all the way to the gate without any
communication at all. Believe it or not, other aircraft may not have
to be vectored out of your way, or even informed about your problem.
But in reality, the pilot would simply peek at the coffee-stained nav
chart and dial up another controller on another freq and ATC will say
another frequency to come up on, or "stay with me."

For navigation on frequencies 108.00-117.95, besides being rather
strong signals, the nature of the modulation is such that interference
would have to be strong and be just so, to cause navigational error.
More likely there would a panel indication of an unusable signal --
because the receiver must be designed this way, and the pilot can
listen to the nav audio to hear the problem. The aircraft is also in
radar contact, so that if the pilot were to wander off course --
you're allowed a fairly wide margin -- ATC tells you if outside the
margin or not following a clearance if given a "direct." If you can't
rectify it, you simply ask for radar vectors, or switch to GPS nav, or
vice versa, or clearance to go direct to another nav beacon off the
nose, or GPS direct if equipped.

Now the same considerations apply to flying the approach and landing,
but the pilot would rather not have to deal with potential
interference to either nav or comm, especially if the airport is 1/2
mile visibility in fog. Thus, it's not too uncommon for the pilot to
grant permission to use a radio device only while in cruise.

Also, ATC will be able to tell the pilot that other aircraft are not
reporting a problem, a hint of possible interference from inside the
cabin. But has anybody ever heard a cabin announcement during flight
to turn off any devices?

Fred F.