Several years ago, when I was trying to get admission into my engineering course, the university's computers crashed because too many people were speaking on the mobile phones and the system could not handle the inteference. As always and as with automobiles, model airplanes and cell phones should not be used together. I havent seen any hurt a model yet and radio wave inteference may not occur, but the high magnetic fields created may affect TX circuitry and there is always a first time. Dont switch off your mobiles at the field, they are for emergencies; use them as such. Model airplane engines are too noisy to use mobile phones in the pit anyway

By the way, it is a good idea to switch off your phone if you are about to get interviewed

Ameyam