NavList:

Lu, you wrote:
"How would that work given that major cell carriers use different modulation systems. Would a pico-cell be required for each different carrier? Would it be even worse on international flights?"

Sure. But it's just one box. There aren't that many standards. And you know, you buy what you need depending on where the aircraft will be flying. And remember, this technology has been around for YEARS. The American obsession with the "risks" of cell phones in airplanes is an aberration. I remember reading something a couple of years ago about Emirates (airline) passing the one million in-flight cell phone calls milestone.

"How about data?"

Many flights now have on-board wifi. It can be fun. You shoot a photo looking out the window and immediately post it online somewhere. I first did this nearly two years ago (and I may have posted about it here). You can kill time with plain old Internet browsing. A year and a half ago on "gogo" in-flight Internet, it was $9.95 for an hour of wifi. Today it's $5.00. For entertainment value, it's certainly worth it. And it satisfies a yearning I've had since I first flew aboard a jet 40 years ago: you look out the window and wonder, "what is that river? what town is that? what's that funny circle in the middle of the desert?". With some rough idea of where you are (or GPS from a smartphone), and various online mapping resources, it's now easy to answer all those questions and more.

You asked:
"Last but not least, how would these pico-cells communicate with their respective networks??"

I believe it's by satellite. The "pico-cell" sends up all the signals from active phone calls to the satellite. The satellite bounces those to a ground station. And then the ground station routes the calls into the phone network. Obviously with all that going on, calls are quite expensive, so this is not for casual conversation. But in a pinch, it can be the best way to get something done.

I agree completely with Gary LaPook that cell phones CAN communicate with ground towers under much broader circumstances than commonly imagined. But the problem with multiple cells is very serious. The cell system is intrinsically two-dimensional. It can't reliably cope with phones at altitude. While Americans were obsessing over safety, engineers in other countries figured this all out years ago, and, as I noted above, the system they developed has been in use on international carriers for years. The solution is to rely on a "cell" that the airplane carries with it. Cell phones talk to that "cell tower" inside the aircraft, and then it routes calls through a satellite. If that on-board system is turned off, which would have been the case on the Malaysian Airlines flight if they had such a system (apparently they didn't anyway), calls can still reach ground stations when flying over populated areas. So I agree with Gary's theory that the absence of distress calls from passengers is strong evidence that whatever happened was either unremarkable to passengers or they were overwhelmed somehow in less than a minute. Note that text messages, especially, would have been transmitted. If you send a text, and you're out of range, most phones will re-try periodically until it goes through. If there had been a hijacking, surely at least one passenger would have had time to tap out "omg we're being hijacked" or equivalent, and that message would have been transmitted during the west-bound over-flight of Malaysia.

Back to the topic that started this, they seem to have narrowed down those "ping" signals to the southern arc of the previous map, and they're looking at a region "the size of Arizona" in the far south of the Indian Ocean where they believe the plane went down. I sure wish I could find a source that discusses the technical side of this analysis. It sounds fascinating. I imagine we'll hear all about in months ahead...

-FER

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