There seems to be a lot of good points posted earlier and many not so good as usual; most likely old wives tales. Having worked for a major airline in field of interference I do believe I have some knowledge. The problems with cell phones are (note: I am not going to cover ALL different types of radios such as GSM, CDMA, TDMA, 900, 1800, 2400 MHz, 0.6W, 0.01W, altitude, plane type, etc., just TYPICAL situations), (IN BRIEF !!!):
- The almost perfect metal tube for keeping the RF signal within the cabin. This means that the cell phone radiation of 0.6 Watts will mostly bounce around the cabin until it is absorbed or radiated outside. One way to unintentionally guide the radiation is through cabin wiring, especially unshielded, but even shielded wiring can "guide" EMI into the electronics bay along the outer shield !!
- Also the cell phones would transmit at almost full power to overcome getting the signal through the small windows.
- On a 400 passenger plane if 25% are using their cell phones that'll make 60 Watts of total power bouncing around the cabin. Human flesh does absorb EMI but not enough. In the "tube"/cabin you have this power bouncing back and forth until it finally gets absorbed. The power keeps adding up UNTIL it is absorbed (leaked) somewhere by something. The choices are: windows, people, seats, wiring, etc... So in a cabin you could conceivably have, in an extreme case, an effective power level of almost 500 watts (albiet not sustainable). The solution would be to add absorber material all over the cabin or use very few phones.
- At the airline I was at, the cabin pressure would decrease every time they would transmit on the high power HF over the oceans. It was latter found to be a leaking coaxial cable leaking some of the high wattage HF which was absorbed by the newest fine electronics pressure regulator that was not properly designed for a high EMI radiation environment.
- The problem with using a cell phone at high altitude is that the atmospheric losses are sooo low that a cell phone can be used for many miles (approx. less than 50 miles). If the plane is flying near a city like New York you could theoretically interfere with many many cell sites on that frequency, especially during peak periods. Try this out. Go to the top of a mountain or building near a city but away from nearby cell antennae and see how long your phone call lasts during peak period before it gets dropped. Where I live near the top of a mountain the nearby cell tower is designed to limit the power on the mountain. I have better call reliability at sea level than on the mountain near the city.
- I have used a cell phone on a C172 and the cell operator came on line and from the background noise guessed that I was using a cell phone from high above and killed my phone call even though I was calling for aviation purposes. The operator had the kindness of telling me just beforehand.
As for electronic low power devices like games the power levels are much lower. Laptops emit more power. The problem is that if most people use laptops, especially on distant final approach, the TOTAL interference can be a challenge to shield from the weak navigation signals. Future airplanes are being designed accordingly but it will take a ling time before the old ones are replaced or retrofitted in the far future. If a pilot keeps complaining about the interference I would strongly suspect the problem is no longer with the computer users but rather the airline maintenance cost cutting.
Enough for now
Keep the blue side up (wherever up is )