What is the deal with electronics and radios on airplanes?

I must admit I was somewhat reluctant to address this topic because there has already been a lot written and I fly a lot and I definitely don’t want to offend anyone trying to keep me safe on an airplane.  Nonetheless, I was encouraged by one of my co-workers today as we pondered many of life’s mysteries.  So for those of you who fly, you know that that there are at least a couple of things that are puzzling about electronics usage (or maybe more).  First the flight safety speech says that during the flight, once it is declared safe, you are not allowed to use “televisions, radios, cell phones or any other electronics that operate in a transmit mode.”  Second, we are told can’t use any electronics between the ground and a mysterious altitude which I believe to be around 10,000 feet.

Dispensing with the easy ones first, doesn’t anyone in the FAA or any of the other world aviation bodies know that televisions are NOT transmitters.  Listen carefully to the speech the next time you fly.  They are not windows, they only go one way.  Also, I must admit that the little video screens on the seats and on my computer look very much like televisions.   Okay, ignoring the television problem, we have the issue of using radios of any kind while in the air because they might interfere with the navigation system.   For this I encourage all of you readers to do your own research and observe the following:  the electronics that go into aircraft are some of the most robust electronics around.  The testing for immunity is unbelievable because they want them to function in all kinds of bad situations.  There is no way a legal low power cell phone. Bluetooth headset or WiFi interface is going to take down the plane – somehow we all know this, but are afraid to declare that the emperor has no clothes.  I won’t tell you that I’ve tested the cell phone in flight because that would have been wrong, but I will tell you that most cell phones go to sleep if they can’t find a network so they probably go to sleep at 35,000 feet. To make it worse, some flights are actually trialing WiFi based internet service – figure that one out.

Next is the issue of any electronics when operating between the ground and the mystery altitude.  Okay, so we’ve taken out the radios, and still we run the risk of taking down the plane?  For those of us that design electronics, we know that they need to meet very strict electromagnetic emissions and immunity guidelines precisely so they CAN’T interfere with other electronics and so other electronics can’t interfere with them.   Hence, there is no way that a plane full of laptop computers and iPods are going to take down a plane.   Hence, the only explanation that I can come up with is that we don’t want someone accidentally bringing an illegal, very high power, say 10 watt,  VHF jamming transmitter on a plane and turning it on during the flight.