Hi all, I asked my hubby ("VStar") who works as an engineering tech at Wulfsberg Electronics, who designs and manufactures nav/comm electronics for aircraft, etc. Dan is also very experienced with anything to do with 2-way radio, RF etc. I asked him if using a GPSr on an airline could cause any interference with the airliner's systems (computers, navigation, radios, etc and whatever.) I really wanted to know, if for nothing else than my own safety, and I will admit that I have "snuck" a peak at my GPS that I turned on, on a flight, to see how fast we were moving and the altitude. It was fun to watch it move, to punch in a waypoint near home and see how far it was, etc... His answer, (always on the edge of my technical understanding,) is that it is POSSIBLE but UNLIKELY that it would cause any interference. These GPSr's generate (oscillate) at some internal frequencies, and if the frequencies were close to something on the airline, it is possible to interfere. He said that most people think that because it is a receiver, that a GPS doesn't "transmit"....but apparently it does internally. His explanation was MUCH better than I can remember to type....and some of you may have the knowledge to know also. But my hubby is one who would know. Then I got to thinking....I am flying in an airplane, way up high in the air, or taking off, or landing....if there is even a SLIGHT possibility that something from a GPSr that I, or anybody has, COULD, however UNLIKELY it is.....could interfere....what would the result be? A missed reading? Annoyance? Best case, nothing....worst case...we CRASH??? SO, I decided that I don't want to risk even a slight chance if it might mess up the little metal tube whooshing thru the air at 600 mph..... However unlikely, there must be a reason why they have restrictions that they sorta sometimes enforce....and to me, it isn't worth it to take a chance. But that is just my opinion, bolstered by hubby's knowledgable opinion. Hope you travel safely! Trisha "Lightning" Prescott I have ALWAYS asked, and have ALWAYS been told NO!   I recently took a round-trip on Delta, and as I couldn’t find anything in the magazine specifically allowing or prohibiting GPSr usage in-flight, I asked the flight attendant if she could check with the “front office”. She returned a few minutes later and told me the captain had said that as long as it didn’t require an external antenna it would be okay. So my four hours to Atlanta seemed much shorter.   It was kind of funny in a way, as I did have an external antenna on board with me (we are so spoiled by reception quality here). I’d often thought that if I were going to sneak, it would be far less conspicuous to just hold the antenna up to the window and keep the GPSr hidden in my lap, or behind a book. But since I had the green light, I just used the built-in antenna (and got a sore arm from holding it up to the window).   On the return flight I was in an aisle seat, so I didn’t even bother to ask.   Let’s face it, it’s always easier (and probably less hazardous to the airline employees’ careers) to simply say no. I was lucky. I would still ask whenever presented with the opportunity. Perhaps as the airlines get more requests, they’ll consider the issues a little more thoroughly instead of issuing blanket prohibitions.   Steve Team Tierra Buena