It’s commonly believed that using cell phones and other types of electronic devices on an airline flight would interfere with the navigational system. Theoretically, a wireless device like a cell phone could interfere with an airliner’s communication system; the truth is that these systems have been shielded from electromagnetic (EMF) interferences since the 1960’s.
The real reason for the ban has to do with their effect on cell phone towers. If you’re flying at a typical cruising altitude of 35,000, a signal from your phone could reach hundreds of cell towers at once, causing a major jam-up, which would disrupt cell phone communications on the ground.
It’s probably a good thing that this ban is in place. An airliner is a metal tube which is a nearly perfect structure for reflecting the EMF emitted by electronic devices like cell phones. The electromagnetic radiation emitted is in the form of microwaves, same as those in your microwave oven. If, say, 150 passengers on a flight from NY to Chicago all started using their cell phones during the flight, there would be a considerable amount of microwave radiation bouncing around inside the plane.
What effect would this have on the passengers? No one really knows at this point in time, but there are certainly a number of possible adverse effects that could be produced in both the short and long term. So, until we know a lot more about the effects of microwaves on humans, turn off your devices, sit back, relax and enjoy the flight!