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Weekly Column

War Flying: Bob wants to put WiFi in the Sky

Status: [CLOSED]
By Robert X. Cringely
bob@cringely.com

Why can't we use portable electronic devices in aircraft? Nobody seems to know for sure. There is the theory, of course, that listening to a CD player at the exact wrong moment will send your airliner crashing to Earth. That we're allowed to undertake such dangerous behavior above 10,000 feet is based on the idea that from that altitude, somebody is going to notice in time to stop the power dive. As a pilot for 34 years and a computer guy for nearly as long, my considered opinion is that this threat is exaggerated, and the point of this column is to lay out my plan to find whole new ways to use electronic devices aloft.

The primary reason we are restricted as passengers from using airborne electronic devices has to do with regulation and liability. In the United States, the Federal Aviation Administration (FAA) commands the air while the Federal Communication Commission (FCC) commands the airwaves. The FCC has no problem at all with you listening to your CD player in flight, but the FAA does -- to a point. So the agency that wants to control your use of an electronic device doesn't really have jurisdiction over the device, just over you as a passenger. And the FAA's objection to your using an electronic device comes down to their lack of control over the manufacture and certification of that device: If the device was FAA certified, they wouldn't care how you used it. Finally the airlines -- the folks who actually implement these rules -- are mainly covering their flying butts so that there isn't yet another cause for legal action when the next fatal crash happens.

What part 91.21 of the Federal Aviation Regulations actually says about the use of portable electronic devices aloft is that it is up to the operator of the aircraft. The Feds (bless their engineering hearts) actually lay out a proposed plan for air carriers to have passengers turn on all their gizmos at cruise altitude, see if there is any interference, then start turning stuff off until the offender is discovered with the goal of creating a database of approved devices. If you think about it, this process of discovery could be completed in just a few days, but for some reason it has never been done. Instead, some manufacturers (well one, Airbus) have gone to the effort of certifying some of their aircraft as compatible with certain kinds of electronic systems, mainly WiFi. Now you can surf the net on some Lufthansa flights, and the connection between your notebook computer and the airplane router is by WiFi, though the actual connection to the Internet is by satellite.

The FCC, not the FAA, has traditionally objected to the use of mobile phones in flight. And this restriction comes down not to any safety consideration, but to a commercial one. Cell phones work so well in the sky that the FCC fears they could command large swaths of bandwidth is one airborne telephone could reach dozens of cells. There may be some validity to this claim, but that validity is waning as most cell systems go digital and smart antennas make better use of the spectrum.

There was early this year a report that a Samsung dual-mode phone caused GPS interference on a non-commercial flight. NASA bought that now-discontinued model phone on eBay, tested it and verified that while the phone met all FCC emissions limits, it could interfere with GPS reception in PCS mode. This result is sobering, but I suggest we look a little deeper into the NASA report, which is among this week's links. There we will see that the phone RF emissions DIDN'T interfere with GPS, but were simply judged as being CAPABLE of interfering.

This distinction is important. If your car is in an accident and finds its way to a modern body repair shop, they'll throw it on a fixture that uses lasers to show how the accident has caused the car to be bent out of alignment. Repairing that damage can add thousands to the total bill. But if they took the same model of car direct from the dealer showroom and measured it, the warping could be the same or worse because cars just aren't built to that level of precision. The lasers aren't lying, but they are measuring production variance, not damage. The same goes for NASA's GPS interference study, which showed the Samsung phone's emissions were lower than those of many other portable devices including pagers and notebook computers.

Should we ban all these devices? Yet people sometimes forget to turn off their mobile phones, and there are probably several active phones operating continuously on EVERY commercial flight. Why aren't planes dropping from the skies? And won't this effect (even if it was more than a novelty) be controlled by implementation of the Wide Area Augmentation System (WAAS) for making GPS more precise and to detect exactly such anomalies?

Mobile phones are already used in flight, many of them legally. There is in the U.S. a system called AirCell that specifically provides mobile phone service in flight using a unique network of cell sites with directional antennas that point aloft like inverted umbrellas. AirCell, which has been in business since 1991 and offering service since 2000, is now entering the Internet Service Provider business, too, using the same ground stations for WiFi, which they claim will be cheaper than the satellite Internet services currently being introduced.

But I wonder if AirCell really understands the word "cheaper?" After all, they sell for several thousand dollars what is essentially a cell phone, then charge you $1.60 per minute to use it, all because the FCC wants to protect the mobile phone companies from aerial users. Right now, many aviation headsets come equipped to work with your regular mobile phone, suggesting that at this moment there are probably hundreds or thousands of people flying around in little planes and yacking their heads off. Yet for some reason the mobile phone companies don't seem to be complaining. Have you heard any complaints?

So here's my plan for really cheap aerial Internet service. I'm preparing a number of experiments using a Linksys WRT54GS 802.11g router mounted on the roof of my house in Charleston, SC. The router is running Sveasoft firmware that gives me direct control of transmitter power if needed. I'll be testing it with a variety of antennas, mainly omnidirectional but perhaps I'll try a sector antenna, too. The other end of the wireless connection will be a second WRT54GS mounted in my funky homebuilt airplane. Operating the pair of routers as an Ethernet-to-Ethernet bridge will give me much higher performance than I could ever expect from just using a WiFi card in my notebook computer. And I'll be testing a variety of antennas on the belly of my funky airplane, too.

What I expect will happen is I'll be able to fly near Charleston and connect to my home network at 1-2 megabits-per-second. I'll learn which antennas work best together. I may even place or receive a few VoIP phone calls using phone software running on my notebook computer. It will be interesting to see how far I can get from Charleston before losing service. It will be VERY interesting to see whether I can connect to WiFi base stations other than my own. I'm guessing such war flying will be possible, though I can't guess how reliable.

There are good reasons to want to surf the net in flight. NexRAD radar images can show me what the weather is like up ahead. Internet-based flight planning software can help me update my flight plan based on winds aloft. I can have pizza waiting when I land.

Now -- strictly because I am twisted this way -- let's take this experiment a step further. Sveasoft supports mesh networking, though with a practical limit of three hops. Aerial WiFi links of 10+ KM ought to be possible and maybe a LOT longer. The hardware cost of a WRT54GS and antenna are on the order of $100. There are, at the moment I am writing this, more than 1,000 small aircraft flying on IFR flight plans in the U.S. So for not very much money you could have a 1,000-node aerial mesh that could serve not only airborne but also terrestrial users. Triple the money, and you could put in each plane a Locustworld mesh with two radios for each node and truly robust mesh networking.

There are 25,000 mobile phone cells in the U.S., but AirCell pretty much duplicates that network using 115 specialized cell sites aimed skyward. While WiFi ranges are less than cell ranges, a 1,000-node mesh is huge -- effectively bigger than any hotspot network now in use. There have long been proposals to park Internet hubs in the sky over major cities in balloons or circling aircraft, but the problem is always the cost of running that satellite in the sky. This solution eliminates that cost of operation, replacing it with a symbiotic relationship where aircraft owners benefit from volunteering the use of their planes by getting free airborne Internet service.

It's just an idea, but I'm going to try it out. Let the first node be funky.

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