[304065]

As any beginner pilot knows, VHF and UHF are line of sight. From an elevation of 1000 feet you can see many, many towers. This is the reason-- from FL 350 cruise you could lock up many towers on the same frequency.

Also, every radio uses a "local oscillator" to compare the received signal to- these cause RF emissions. Do you really want to see what happens if the pilots happen to be shooting an ILS Cat III into the fog?

The REAL reason is safety related but not in the way you might think. Standards of etiquette being what they are, the cellphone ban avoids the hundreds of potential episodes of choking the living beejaysus out of your fellow passenger who jabbers on a cellphone ALL THE WAY FROM NEW YORK TO LOS ANGELES