GPS' Gilded Age ends

Last trip story: Every air traveler is aware that use of "personal electronic devices" is prohibited on commercial airliners in the takeoff and landing phases. During those times, the pilot is using a lot of air-to-ground communication and navigation equipment, and its pretty important that it all function without EMI (electromagnetic interference) from the passenger cabin. But for the majority of the time in the air you are allowed to use certain gizmos -- CD players, laptop computers and one-way pagers being common examples. For years, since 1999 in fact, I have passed time on airplanes holding a GPS receiver to my window, scrounging satellites to get a position fix. I've always thought it was neat to be able to identify specific towns and highways from thirty thousand feet, to try to find landmarks and so forth. I also thought it was pretty cool to note a ground speed of 600 mph on one part of a Tokyo-to-Detroit flight when we were catching the jetstream just right.

Well imagine my annoyance when the American Airlines stewardess told me I couldn't have my GPS on in-flight. I was incredulous. "I am not allowed to use a receiver?" I asked. The stewardess replied with "no" and a stream of four other negative phrases for emphasis. So I scrounged through the back of American Airlines' flight magazine and sure enough, GPS receivers are now on the naughty list for the duration of flight. I was annoyed for a few reasons. First, the stewardess was harshin' my geek buzz and wasn't even trying to be nice about it. Second, I just felt in my bones that this was an ad hoc prohibition. I'd played with Magellan and Garmin receivers on dozens of flights and the greatest reaction I had provoked before was just a cursory check that I wasn't wielding a cellphone. On occasion, a stewardess would actually take interest: I told one once that the GPS said we were at 29000 feet. To my surprise, she then went to the captain to check my story and came back later, marveling that the little receiver was right. But apparently the novelty has worn off these days and the fun has to come to an end.

After my wife was done laughing at me (third annoying factor), she related my predicament to a United pilot who happened to be seated to her right. The United guy was commuting into O'Hare so he could start his work shift that afternoon. The initial reaction of the United pilot was surprise: "I didn't know they were prohibited." I can understand the surprise, considering that the rule varies from airline to airline, plus he knows quite well that the aircraft itself has its own GPS receivers operating in harmony with the rest of the avionics. Once past that, we started talking about the fact that any electronic device that has switching currents is going to produce EMI: radios, TVs, computers, games, you name it. And the pilot added that the aircraft has wires that run the entire length of the cabin for receiving signals, control, and so forth. Now, the chances are overwhelming that any one individual's GPS is no problem at all. But maybe twenty poorly-made units acting together become a problem when you add that to the twenty laptop computers and personal MP3 players already in operation. The United pilot said, "Obviously the airline isn't going to test them all to see which models are okay, so..."

I believe that to a great extent the economics of the situation is trampling the science. I would be willing to wager that my eTrex Vista, with its sub-watt power, low-res LCD and FCC Part 15 Class B compliance, emits far less EMI than your twenty-watt, 2 GHz, SVGA Thinkpad. I'd offer the Vista itself in that wager, and throw in the MapSource CD too. But the airline knows darn well that they'd be driving away their top fares if they kept businessmen from using their computers. You cannot say the same thing for the occasional GPS nerd, so I see how I wound up on the short end of that rule.