Cringely: Wi-Fi in the Sky 158
Boiled Frog writes "In Cringely's latest article, he describes his plan to test a wi-fi connection between his house and his plane using two LinkSys 802.11g routers. He plans to experiment with various antennas to see which works the best."
Tragedy of the commons... (Score:5, Informative)
A few rare rulebreakers won't have as much affect on the network as if the rule was repealed and everybody on the plane was doing it. If 200 people on a plane flying overhead are on their cell phones, that'll be a much different situation than what's never really been tested.
Re:Cringe-ly (Score:3, Informative)
Finally, I'm not going to spend $1000 having an A&P mechanic install my $100 wifi router in my airplane. If I could just slap it in myself, that would be one thing; but with an airplane you're going to need a Form 337 approval at least, if not an STC (Supplemental Type Certificate). No big deal on the 337. It just takes time and thus money. That's money I'll be spending just help the wifi cloud when I happen to be flying? Uhh, I'll pass.
Sorry, this isn't true. This is not required for homebuilt airplanes if the original builder installs the hardware. The builder of a homebuilt plane is given a repairman's certificate by the FAA that allows them to do all the maintenance on the aircraft. The builder is also designated as the 'manufacturer' of the aircraft, so he or she can approve any equipment as 'original' for the airplane. No A&P required.
Re:Cringe-ly (Score:5, Informative)
Ask yourself: If it were the case that mobile phone use would crash a plane every 10.000 landing, would you allow it to be used? Or every 100.000 landing? Especially in the US with the system of suing people for negligence?
(AFAIK, one reason for not being allowed to use anything during takeoff and landing is because mobile phones, electronic games and laptops are too good at playing projectiles if the plane has to make an emergency stop...)
VFR NORDO? no problem. IFR? Safety hazard. (Score:3, Informative)
It depends on your flight conditions. I assume Cringely is flying VFR (Visual Flight Rules), so if he is a competent pilot familiar with the aircraft, he should theoretically be able to fly his aircraft without any instruments (of course, landing without an airspeed indicator can get your pulse going a little).
However, an airline (or private plane) flying IFR (instrument flight rules) in the soup NEEDS a working attitude indicator and other navigational equipment, as well as communication with ATC, in order to fly safely. The AI allows you to keep the right side of the plane up when you can't see the horizon outside (had JFK Jr. not been such an arrogant, reckless imbecel and had the proper training, this knowledge could well have saved his life), the navigational equipment helps you go where you belong and avoid obsticles you can't see due to clouds, like radio towers and mountains, and the communications with ATC keeps you from hitting someone else flying in the same cloud.
His radio equipment isn't going to affect his gyro and vacuum gear at all (so he won't lose his attitude indicator, airspeed indicator, altimeter, or what have you), but it could very well interfere with navigational and communcations equipment (I've had my cell phone completely jam my comms on one occasion, and while that is rare, it does happen. It happened to me, on the ground while trying to get ATIS, before I turned it off). That could well be a problem if he's flying over a major city talking to ATC and doesn't realize he isn't hearing what they are telling him.
The upshot of all of this? If he's VFR and doing it in an area where he doesn't have to talk to ATC, then, assuming he's a competent pilot who has a passenger messing with the radio gear while he does what he is supposed to be doing -- flying the plane -- he shouldn't have any real trouble. Other than violating various FCC regulations, of course, but that is between him and the FCC.
If he's doing this while required to talk to ATC, he's being foolish. If he's on an IFR flight plan while doing this, he's almost as stupid as JFK Jr.
My bet is on the first scenerio.
Re:Cringe-ly (Score:5, Informative)
There are hundreds of thousands of reasons an instrument could give a wrong reading. That's why there are multi-purpose instruments and backup panels. You check one instrument against another, against how the plane feels, and if possible against what you see out the window. If they don't make sense, there are procedures you follow to figure out which to trust. All the instruments use different methods of operation to basically guarantee that you have at least some working instrumentation no matter what fails. Some run on the engine vacuum pump, some run on an electric vacuum pump, some use gyros, some are mechanical, some use atmospheric pressure, some are electric, some are radio. This is all covered in basic ground school training and every half-trained pilot could tell you that.
Electric and radio instrumentation is still, and likely always will be, the least trusted instrumentation on an aircraft not because pilots are luddites (we are, in some ways) but because it's the newest and most complex, and so much can go wrong with it. With something running on pitot static pressure, short of the linkages to the control seizing up, it's absolutely bulletproof. If you have come to trust GPS on cross-country flights to the point that you don't think it can be wrong and don't bother to set in a VOR or use your compass and map, then you're a bad pilot and shouldn't be flying. Those things need to be kept up to date and current so that if your GPS system fails, you can shrug it off and look down at your map and everything is just fine.
Oh, and finally: He's not breaking any regulations. Like most other things, the FAA says that the decision of whether to allow portable electronic devices to be turned on is left up to the operator of the aircraft. It even says this in his article. Cringley is clearly the operator of his own aircraft. He can choose to do whatever he wants. The FAA has some extremely important rules that all pilots MUST follow. But they have nothing to do with electronic devices.
Re:Cringe-ly (Score:5, Informative)
Altimiter: barometric pressure
Attitude Indicator: Vac/gyro
Directional Gyro: Vac/gyro
Turn coordinator: Electric gyro
Airspeed: Pitot/static pressure
VSI: static pressure
These are all mechanical in nature. GPS and nav radios are another story, but it's not likely that a malfunction of either is going to cause an accident in VFR conditions. Besides, IFR certified GPS are required to have RAIM which would most likely be out if your phone were interfering with your GPS. My Apollo CNX80 used to report RAIM outages over Quantico, VA until a recent software update. They are VERY picky about signal integrity and the slightest disagreement between sats will cause them to flag.
Just as a disclaimer, YMMV in an A330. I'm sure that large commercial aircraft with integrated flight directors/fms/etc are subject to more problems from interference. Plus, it's not as easy for a pilot to understand the systems of a more complex aircraft/avionics suite and determine what's safe and what's not. I wouldn't hop in even a Malibu Meridian and casually allow my passengers to use a cell phone when I was expecting enroute IMC either.
I doubt that we are talking about a terribly complex set of radios. Don't worry about Cringely, I'm sure he'll be fine.
antennas and routing (Score:3, Informative)
Since the plane is mobile, a fixed directional antenna won't help much (though one that directed most energy upward from the ground station and one that pointed generally down from the plane would be better than an isotropic radiator). A moving antenna that tracks the aircraft's transponder or an APRS [wikipedia.org] device might be reasonable, but difficult to build. What might work better is to use a 200 mw card (like one from zcomax [zcomax.com] or senao [netgate.com] - most cards are about 35mw to allow greater spacial reuse). Or you could use an external 1 watt amplifier.
I'm more interested in the routing protocols for connection handoffs between base stations. AODV and DSR were shown experimentally [uci.edu] to handle extremely high mobility of large numbers of nodes.
-jim