Some of the airlines are still using 60's-era avionics. Cell phones, through design or damage, can emit signals "out-of-band" and right into the aviation navigation and communication bands. Twaddle!
The only instrument I've ever seen suffer from interference of any sort is an ADF which is really just a fancy AM radio. Most of the ILS stuff is just above the FM band. Did you ever have any trouble with your FM radio reception in your car because a passenger decided to use his/her cell phone or listen to an mp3 player.
As for 60's era electronics, I doubt they move the old stacks to new airplanes. The percentage of airplanes in the US commercial fleet that were built before 1980 must be diminishingly low. Here's a picture of planes already out of service:
ML/NJ
The only instrument I've ever seen suffer from interference of any sort is an ADF which is really just a fancy AM radio. I'm an instrument-rated pilot. I know what an ADF is.
Most of the ILS stuff is just above the FM band. Did you ever have any trouble with your FM radio reception in your car because a passenger decided to use his/her cell phone or listen to an mp3 player.
ILS and navigation are just above the FM band. But, aircraft communication is AM, not FM. FM is much better at rejecting interference.
Aircraft VOR receivers measure the phase shift between the lagging and leading navigation tones. ILS localizer and glideslope measure the difference in the depth of modulation between two transmitters with different modulation tones.
But, I have indeed heard interference -- from cell phones, computer devices, and even the local oscillator in a scanner. The difference is that I was listening to a VHF AM transceiver in the 144 MHz band (just above the aircraft band). You see, I also have an amateur radio license.
Aircraft navigation radio technologies are still the same as the 1960's. The radios have gotten better, but they still can't reject a signal that is radiated right on top of the carrier. We are in the process of migrating to satellite-based navigation, but that introduces a new problem because those signals are even weaker than ground-based signals, and are near frequencies used by computing devices.
I explained the reasons why the prohibitions are in effect. If you don't believe it, that's your problem... not mine. The FAA makes the rules, and the rules have been in effect for decades, with only minor modifications:
http://ecfr.gpoaccess.gov/cgi/t/text/text-idx?c=ecfr&sid=bd96dfddf4fbaaf320e8cae4562b47c5&rgn=div8&view=text&node=14:3.0.1.1.4.11.2.4&idno=14
Note that the regulation says: "Any other portable electronic device". It doesn't say "any other type of portable electronic device". It's an important distinction, because it means that the aircraft operator must test individual devices, rather than testing a sample of a class of devices and allowing those.