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Risk Management For Electronics on Aircraft
Phronesis writes "M. Granger Morgan and his graduate student Bill Strauss have a nice article in Issues in Science and Technology about the risks posed by electronic devices in flight. Unlike most articles on the subject, this one neither pooh-poohs the risks ('We have estimated that reported events are occurring at a rate of about 15 and perhaps as many as 25 per year') nor exaggerates them ('RF interference from consumer electronics is unlikely to have figured in more than a few percent of commercial air accidents, if any at all, during the past 10 years.'). Instead, it presents a sensible plan for dealing with the risks that will accompany the inevitable expansion of the range of electronic devices passengers will use in flight, including cell phones and wireless computer networking."
Do airlines that require all mobile phones to be switched off allow exceptions for some new phones such as the Sony-Erikson P800 which provide a non-cellular Airline mode?
Disclaimer: The above comment was made while under the influence of too much coding and not enough sleep.
Given the amount of electronics involved used in the automotive industry these days wouldn't the impact of cellphones have shown up here earlier? (Of course I'm excluding people who attempt to drive with one hand holding the handset, the other leafing through a document and steering with their knees).
You may think me a tired, old, cynic. I'd have to disagree about the tired bit.
Probably the most useful recommendation in this article is the following:
Developing and deploying simple real-time tools to help flight crews detect RF emissions. If airline cabins were equipped with RF detectors, then flight crews could take corrective action when strong electromagnetic emissions occurred. The utility of equipping flight crews with easy-to-use hand-held RF detectors also warrants investigation.
Flight crews could be equipped with handheld RF detectors relatively quickly, which would not only help enforce existing FAA rules regarding inflight use of passenger electronics, but also help gather data that could form the basis of more long-term solutions.
Stop by my site where I write about ERP systems & more
Every time I fly theres some halfwit who gets all riled up when he's told to turn off his phone/gameboy/laptop/pda/whatever. Like he's so goddamned important he just cant stop talking/typing/jerking off while the plane takes off and lands.
They're right up there with the yokels who still think it's hilarious to make a joke about having a bomb, delaying the already brutal security points another few hours. "hey watch this, Clem, Ise gonna tell dem i gots me a esplosive bomb!"
Just sit down and shut up, or drive, or walk. I have places to go.
I don't need no instructions to know how to rock!!!!
Not only in-flight risks, but all types are discussed here. It's one of the more lucid discussions on the net. I've been following this newsgroup for the better part of 20 years.
That's good news. I was hoping to take a large tesla coil with me the next time I go flying.
Trolling is a art,
RF interference stories occur once every little while, and I hope this finally shuts up the people who say, "my cell phone couldn't possibly crash a plane, the greedy airline just wants me to use their satphone".
It's true that your cell phone, BY ITSELF, will not cause the plane to explode and shower the countryside with flaming wreckage. However, look at any airline accident in the last ten years or so. In almost every case, a sequence of one-in-a-million flukes comes together at exactly the wrong time to cause a crash. In the article, they cite probable cases where RF interference caused the airplane to fly slightly off course, or caused errors in the flight controls. If something like that happened at exactly the wrong time, YOU BET there would be an accident, and your cellphone would be to blame.
I'm all for paranoia in the airline industry. It's what makes the flight safer than the drive to the airport.
Toronto-area transit rider? Rate your ride.
Thanks for the tip!
Can I hire you as a consultant for my company ?
--
Oussama Ben Laden
Chief Terrorist Officer, Al Qaeda International Ltd.
The FAA specifies that, "no person may operate...any portable electronic device on any...aircraft" unless an airline has determined that use of the device "will not cause interference with the navigation or communication system of the aircraft on which it is to be used."
One has to wonder if any airline has tested whether pacemakers can cause interference?
Disclaimer: The above comment was made while under the influence of too much coding and not enough sleep.
Idiot. Didn't you see Goldeneye?
They'd need to commandeer a Russian warbird in high orbit by taking over a facility in Cuba. It's just not practical, even if it is highly plausable.
I work as a consultant for an airline, and thus post anonymously :)
:-)
I know that an Airbus once had to restart all the control systems in the air, one by one, to get below 8000 feet. Before the restart, the plane's controls wouldn't let the pilot get below 8000 feet. If I had been the pilot, I'd demand some R&R after landing.
If it suddenly comes out that cell phones do nothing to mess up the navigation of an aircraft, do people really expect the airlines to suddenly say "Go ahead and use your cell phones on the flight". They won't they're making too much money off of those $5 / call Airfones.
However, I'd like to see some sort of official ruling stating exactly which devices can and can't be operated at certain points during the flight. Ideally, this would apply internationally, too (though I'm not sure how that would be regulated, since the FAA has little jurisdiction internationally). I find extremely frustrating when one airline says a device is ok, and another does not. For example, I brough my portable CD player on a flight (a 13 hour flight) and was told I could not use it, because it would interfere with the aircraft's systems. This was on a relatively new 747-400. This was rather annoying, since on the same type of aircraft, 6 months prior to this, a different airline specifically said portable CD players (and tape players, etc) were ok.
Ideally, the FCC, or UL, or some organization could put a little marking on the back of any electronic device to designate whether or not it is acceptable to use during flight. For example, it could be a letter system where "A" indicates that it may never be used (ie: tesla coil); "B" indicates it may be used at any time (digital watch/PDA), "C" indicate it may be used except during takeoff/landing (ie: walkman). Then, instead of having to explain to the stewardess that your PDA does not transmit any RF signals, they could simply look at the back, see the letter "C", and go on their way.
Inconsistency in general (security checkpoints (before the TSA), airline policies, etc) is one of the most frustrating things to me as an airline traveler, and a policy like this could help solve the problem of being able to use my Palm Pilot on one airline, but not other.
There is no sig, there is only Zuul.
Kapton Wiring - The Silent Meanace
TWA warning
I have had small items like Walkmans, Cell Phones and PDAs checked by airport security at checkpoints before. I think they are generally looking for explosive devices etc. I wonder if there is a list of device frequencies that are verbotten on airliners? This would have to be a frequently updated list of devices for the airport security and in-flight personnel to keep track of. Seems like the communications, fly-by-wire and navigation devices would be restricted to a limited bandwidth. I know it is common practice at RC Aircraft Model flying fields to limit who has what frequency. Otherwise there would be lots of little craters in the ground when someones controls get overridden by another radio.
If you can detect my electronic device, please feel free to ask me to turn it off. If you can't - or won't - put a $50 detector in a $5 million aircraft, don't then try and tell me that you're as worried by stray RF as you are by Nelly Nicotene smoking in the toilets.
If you were blocking sigs, you wouldn't have to read this.
There's a completely different risk imposed by another kind of electronic device: video cameras. The risk is that passengers will tape the pilot sleeping at the controls.
Nobody's saying that. The problem is with the landing and taking off. Airlines "say" that the RF interference might mess up the ILS landing system by a few degrees or cause static on some of the electronic instruments. Normal flight isn't that instrument sensitive, but the landing and takeoff are. Sure, they say some devices might screw with the plane in-flight. In this case, "some" airlines just have a blanket statement saying no electronic devices.
Personally, I don't think this is 100% true, but big friggin deal. I'd only be pissed if I was told my cd player or gameboy couldn't be used during thw "WHOLE" flight, but that has yet to happen to me, and I go on several flights a year.
It's a story problem.
If a guy with a new cellphone built by my company flies from Chicago travelling west at 800 miles per hour, and the navigation system locks up, and the plane crashes and burns with everyone trapped inside, does my company initiate a recall?
You take the number of phones in the air (A) and multiply it by the probable rate of disaster (B), then multiply the result by the average cost of an out-of-court settlement (C).
A times B times C equals X. This is what it will cost if we don't initiate a recall.
If X is greater than the cost of a recall, we recall the phones and no one gets hurt.
If X is less than the cost of a recall, then we don't recall.
Everywhere I go, there's the burned-up wadded-up shell of a plane waiting for me. I know where all the skeletons are. Consider this my job security.
Note to M1-ers: a curt but otherwise insightful message is not "Flamebait" or "Troll".
Although there may be a small risk of a cell phone interfering with an airplane's avionics, the people complaining about cell phone use on airplanes are at the FCC, not the FAA.
See, when you're on the ground, your cell phone picks up one or two signals that have line-of-sight to where you're standing. This is how the system is designed. But at FL330, you're going to be in line-of-sight for many, many signals, and your phone will connect to all of them, essentially DoSing the cellular network. And since your cell phone transmits all sorts of identifying information when you use it, it's fairly simple to track you down.
(citation: Say Again Please: Guide to Radio Communications by Bob Gardner. Can't remember the page number ottomh)
If a butterfly flaps its wings in just teh wrong place, that tornado will hit your plane 9,000 miles away!!!
Evil little pretty bugs.
All Troll + "offtopic" mods are meta moderated as "Unfair", because you abused the system.
I know that home-built EMP devices have been the topic on Slashdot before. But I've been thinking that, since it is just electronic components, the parts needed to build an EMP gun/bomb can be brought through screening and onto an airplane. (Not fully assembled, mind you, so that it is a little less suspicious.)
It seems to me that this could result in a catastrophic event (takeoff/landing?), although I don't know the actual results of what one of these would end up doing. Anyone?
God, I hope not. On Amtrak, nowadays, you get five hours of everyone around you shouting into their phones*. It's a blessing that planes ban them -- I shudder to think what a cross-continent flight would be like with phones allowed. Besides, as someone else said, they have a nice revenue source from they phones that they don't want to cut into.
* Mostly illustrating how utterly pointless their jobs are: "Mary? Mary? It's Bill! I'm on the train! Could you call Jeff and ask him if he got the fax Linda faxed to me? Call me back!" If anything, there seems to be too little white-collar unemployment.
What I'm listening to now on Pandora...
I'm with you a 100% there. My concern is that between the morphing of cell phones into PDAs, games, etc. that there will be an across the board ban on electronics. I fly a lot and I would go insane with being able to watch movies and listen to music; but soon there will be very little distinction between them. I personaly feel that the best possible course of action would be to strengthen the system that contral the critical functions of the plane; as to eliminate the risk all together. Then I wouldn't have to listen the old labies bable about their freinds until we reach cruising level and I can tune them out. ;p
"Reality is a crutch for people who can't handle drugs" - George Bernard Shaw (1856 - 1950)
Christ, you tards wouldn't recognise a Fight Club reference if it towered over you like a four story erection!!!!
Mod it up THE FUNNY!
The article states that RF devices may induce currents in airplane wiring. I'm not sure how much commercial airliners cost, but I know it's probably well over 50 million. How much would it cost to use fiber optics instead of twisted-pair wiring? I'm sure relative to the cost of the airplane, it wouldn't be much, and that would eliminate having interference with the wires that must be run throughout the aircraft.
I don't know how much of the concern has to do with the computers themselves recieving interference, but I don't think it's that much. People use cell phones around computers all the time, and I don't think it causes any problems.
The only problem left then is potential interference with airplane navagation and communication systems. Again, the most critical times are when it's closest to the ground (takeoff and landing), but in those environments, I'd expect there to be a lot of cell phone usage by people in the airport, and that would (probably) cause as much interference as people in the plane.
The pilots and flight attendants that are blaming malfunctions on passenger RF interference aren't qualified to talk about it. They say "plane is having problems, passenger is using laptop, therefore laptop is causing problems". They don't have a clue what does and doesn't cause interference, and you'd have to get someone who knows the subject to tell me that that's the case before I'll believe it.
Actually, this is, unfortunately, a future possibility, once the technology reaches a level that Osama (or whomever) could build a home-made EMP bomb. Nuclear technology isn't far off either -- hence the impetus to knip it in the bud now, while we still can...
Now you've made me wonder if they would ask the passenger to turn the pacemaker off for the duration of the flight!
So, let's see. In the first incident mentioned, testimony comes from:
We're supposed to take the word of these obviously unbiased expert electrical engineers that EM interference was the cause of the error. A bunch of groups, some of which have glaringly obvious vested interests in not finding fault with the pilots, suddenly are a bunch of expert electrical engineers.
Even if if they didn't have ulterior motives, they aren't experts in EM, and we're supposed to take their word on the matter? Obviously not... And yet, that's what the author does, by presupposing that someone looking for a straw man constitutes any sort of "proof" of incidents. There's NO way that there could be a problem with the instruments, either in hardware in software, since we ALL know that hardware and software engineers are perfect, so it must've been that guy in first class with laptop...
While the author admits that the inflight ban of cell phones has nothing to do with interference reasons (it just makes life more difficult for the cell phone providers), he tries to justify fearmongering whithout any basis in fact...
What a waste of a read...
...'RF interference from consumer electronics is unlikely to have figured in more than a few percent of commercial air accidents, if any at all, during the past 10 years.'...
If you don't mind adding to your chances of being in that few percent then, by all means, be my guest and keep that phone/notebook/whatever switched on when you're asked to have it switched off.
On the other hand, if you want to minimise your chances of being in that few percent, switch off your device when asked to. A few minutes with your phone/notebook/whatever off isn't going to kill you but a few minutes with it on just might.
When travelling, your priority should be getting from A to B safely. You wouldn't deliberately stick your head out of a train window as it was about to travel through a tunnel so why take similar risks (with the safety of others and not just yourself) when travelling on a plane?
"Accept that some days you are the pigeon, and some days you are the statue." - David Brent, Wernham Hogg
The only real solution is to harden the avionics against RF interference. It is only a matter of time before terrorists use ground-based microwave transmitters with directional antennas to harass airliners on takeoff/landing.
The very fact that FAA and FCC panic over passenger electronics is clue #1 that we have a problem and it goes well beyond the average moron with a cell phone.
Just curious... obviously if the plane exploded in a ball of fire because of your transgression, you would not be able to report back.
But for those who survived. Did the cell phone actually work? I'd imagine it would be hard to get reception. Either you're over the Grand Canyon and there's no towers, or you're over a huge city and there's way too many in line of sight. The phone would have problems deciding which one to use.
Any real world experience?
The problem isn't so much of the everything-morphing-into-one-uberdevice variety but of the 802.11* variety. I have a number of devices now that have wireless built in, and I have to start the device (including wireless) before I can turn it off. If I forget to do this before I get on the plane, well, I suppose I can hope nobody notices the plane making a dive while I quickly disable the network)
If I have been able to see further than others, it is because I bought a pair of binoculars.
I may be wrong, but don't you need a small nuclear device to create an EMP. If one of those was activated on a plane, I suspect that instrument failure would no longer be an issue.
If somebody came up with a non-nuclear device for deliberately interferring with flight systems, it would rapidly become illegal to take anything on the plane that could potentially be such a device. You'd find that all your electrical items will have to be packed separately so that they could be placed in a special shielded part of the cargo hold.
All I want is a secure system where it's easy to do anything I want. Is that too much to ask ~~ Randall Munroe
You forgot to read the article. The primary reason cell phones are not used in airplanes is so they do not overload the base stations on the ground, as a cell phone at 33,000 MSL can activate many such base stations.
this article suggests to me that a fun way to kill a planeload
of people would be an emp pulse.
-I like my women like I like my tea: green-
Some articles on a new system being introduced:
RMN
Denver Post
~afniv
"Man könnte froh sein, wenn die Luft so rein wäre wie das Bier"
Richard von Weizs
This is really silly. We should be testing the avionics of planes to see if they can take RF of the differing frequencies that could bother it. If it can't, the plane should be grounded until it can be hardened to handle the RF. RF hardening is a science that the military industrial complex is quite apt at. "That's expensive, why don't we BAN USE OF the devices," cry the economically minded. In a day an age where you're in deep crap if you forget to take your pocket knife off a keychain, its quite possible to bring a laptop on a plane that can fake signals and jam avionics. Either ban laptops (yeah freaking right) as carry ons, or HARDEN THE FREAKING PLANE LIKE YOU SHOULD HAVE DONE ANYWAYS. If you're worried about RF leakage out the windows, put a metal screen over them. Come on folks. We KNOW how to shield things properly, and we know how to test if we did it properly. The test equipment doesn't cost that much (100K, which is nothing for an airline). On another rant, why don't cell base stations detect the case where the idiot is obviously up the the air? That's a problem that should be easily solvable via electronics, and not by regulation.
Want to see every step I took to start my company? http://www.rowdylabs.com/blogs/pitchtothegods
Who wants people to use cellular phones?
I know that I do not.
I find it VERY rude when I am forced to hear someone talking loud to someone that does not matter to me on a cellular phone in public. In general the worse the connection, the louder the person talks... I can only imagine that volume people will be yelling at when they are 35,000 feet above ground.
Think of all the people reading, sleeping, or using headphones to provide peace to those around them.
KEEP THE AIRPLANES PHONE FREE!
Justen Stepka
That was an excellent article. Easily one of the best I've ever read on the issue. One passage in particular caught my eye.
"But faced with the slimming down of work forces, expanding job responsibilities, and the retirement of older personnel who had specialized knowledge and experience in electromagnetic compatibility, the potential for problems increases..."
Boeing has already laid off a huge number of engineers, more than I think they ever should have, all in the name of "Shareholder Value."
I wonder where the "Shareholder Value" will be if the lack of one or more of those laid-off older guys, many of whom probably had all the knowledge ever needed regarding electromagnetic noise, will cause serious problems when future airliners are not properly designed, in terms of their avionics and wiring, to stave off interference problems?
Bruce Lane, KC7GR,
Blue Feather Technologies
And a little bit lazy, I must admit, to search the web for technical info on RFID tags, frequencies, modes of operation, range, etc...
So, if someone else and knowledgeable can answer it, I will be glad.
Achille Talon
Hop!
Life is like surrealism: if you have to have it explained to you, you can't afford it.
Shouldn't the threshold for airplane sensitivity to RF interference from passengers be much higher now that we've realized the possibility that any of the passengers may be malicious and suicidal? If we're worried about stuff like CD players that is designed to run for hours with minimized EM emissions, then aren't we completely vulnerable to electronics of the same size designed to put 100% of their power output into EM interference, to do so in a big burst at the worst possible time, and to superficially look just like any of the other electronic gadgetry that gets by airport luggage screeners with no trouble?
I am a retired military avionics technician, and a former electromagnetic compatibility engineer. I will never set foot aboard another commercial air carrier until there are strict prohibitions against all electronic devices on aircraft that are not part of the accepted avionics package. Period.
Why not just make the passenger compartment a faraday cage? Completely isolate it from the rest of the aircraft(separate, filtered power and comm lines). Coat the windows with a conductive film, and then even if some idiot turns on his cell fone its not going to interfere with anything, much less get a signal.
Then, since the passengers will be properly separated from the crew we can drop all of the stupid pocket knife restrictions and fire half of the new airport security folks.
If the airlines weren't such a bloated, subsidized monstrosity, they might have solved this by now.
http://www.masturbateforpeace.com/
Yet another article allowing geeks to whine about how the airlines won't let them play with their techno-toys...
When will you geeks realise that YOU DO NOT FUCK WITH SAFETY. Interference from mobile phones can prevent a pilot hearing important information for air traffic control. Now if you think playing with your toys is more important than the safety of the aircraft, you are a complete and utter fuckwit!
"Information wants to be paid"
If you wanna play with your toys, take the friggin' bus instead. If you want to fly, you'll agree to do it their way, not yours. Whenever I fly and some jerk is disturbing me with his electronic toys, I wish they'd make him step outside the cabin.
fact1:
most cell sites have their antennae tilted downwards.
fact2:
planes usually cruise at an altitude of 26k ft or more. this is about 5miles.
fact3:
most airliners cruise on the order of 500 knots. this is about 550mph.
educatedguess1:
most networks probably arent designed to soft/hard handoff a mobile traveling at 550mph.
inference1:
given fact1 and fact2, physics will make it attenuate RF propagation and make a gd signal almost impossible.
conclusion:
given inference1, educatedguess1 and fact3, it is likely that any call u can make is not going to be good.
reaction to conclusion: read a book.
As a PhD Electromagnetics Engineer, I'd suggest the airlines follow the "honeypot" approach used for internet security. Install several relatively inexpensive RF detectors near critical equipment and circuitry. If there's no interference the detectors would never go off, so if you had even one detector fire, you'd know there was a potential problem and could investigate further (or ask everyone to temporarily discontinue use of 'portable electronics').
Regarding a cheap portable RF emissions detector: get an AM radio. They are nicely sensitive to the pulsed and chopped energies emitted by digital electronics.
Regarding shielding: airlines could mix in chaff (strips of metal) into the plastic used for aircraft interiors. This would deaden the RF environment inside the aircraft and prevent strong reflections and concentrations of RF energy in inappropriate locations. Of course, it would kill cell phone reception once you step inside the plane
BTW, Cell phones should not be used at gas stations either. Some analyses suggest that an actively transmitting cell phone could create a coronal discharge from the metal on a car that could ignite gasoline fumes. Its not very likely to happen, but the consequences are none too pleasant.
Two wrongs don't make a right, but three lefts do.
The problem is (mainly) not due to wiring.
The problem is in fact that the radio navagation aids 'navaids' operate at low frequencies and use geo-displacement / frequency modulation as part of the navigation method. The most common example, the VOR, or 'very high omnidirectional radial beacon' sends out a radially sweeping signal at 3600hz. This is such a low frequency that it can be affected by non-primary frequencies in small electronic devices. For example: CDMA/TDMA cellular phones, while operating at (at least one of them) 1900Mhz (AFAIK), they have polling frequencies that could be very close to 3600hz.
I would really like it if GPS was the primary navaid, but it is not. GPS was just recently approved (in the last two weeks) for IFR approaches, and until now, it wasn't even legal to conduct a full flight to commercial minimums (I think it's Category III ILS) - making it useless to commercial air carriers. Further, it's going to take the FAA at it's current rate, over a decade to convert the terrestrial navaid approaches and nav plates to include GPS routing and approaches.
Thus - here's just one example, where it's not the routing, and hopefully this will clear up the radio frequency problem... When I take off with my CFI into IFR (clouds, zero vis), I guarantee you that we both turn off our cell phones! (and that's in a 4 seater cessna 172)
BANIA: I just stopped by to thank you. That risk management stuff you wrote for me? It's killer!
JERRY: Risk management?
BANIA: Aw, it's gold, Jerry! Gold! I got all these corporate gigs and even Cynthia took me back.
- Seinfeld
No. Obviously, we need to do away with crash investigations, since air crashes are so unpredictable, and everybody is trying their best anyway.
Toronto-area transit rider? Rate your ride.
No need to smuggle it onto a plain, just put it near an airport and detonate it when a plane is landing or taking off.
This sig wasn't worth reading, was it.
Jerry: "Risk management? Why do you have to write about that?"
George: "I dunno. I guess it's on my resume..."
"PC Load Letter? What the $@#% does that mean?!"
Fiber is very difficult to certify for installation in aircraft due to the requirements of the physical environment. Its a challenge to get a mix of materials and connectors that survive the vibration, temperature range, and humidity requirements specified by the FAA. Its even harder to get the right mix to operate in the worst-case environment with acceptable loss.
I worked on a project to put an entertainment system that used fiber optics on planes. Although we qualified some fiber that could survive the environment, the materials that allowed it to do that failed the smoke & toxicity tests when burned. And since it was an entertainment system, we could ignore the fact that it might stop operating under some conditions - something you wouldn't want to do with critical flight control systems.
In airline crashes, is not a few percent too many?
135.144 Portable electronic devices.
(a) Except as provided in paragraph (b) of this section, no person may operate, nor may any operator or pilot in command of an aircraft allow the operation of, any portable electronic device on any of the following U.S.-registered civil aircraft operating under this part.
(b) Paragraph (a) of this section does not apply to -
(1) Portable voice recorders;
(2) Hearing aids;
(3) Heart pacemakers;
(4) Electric shavers; or
(5) Any other portable electronic device that the part 119 certificate holder has determined will not cause interference with the navigation or communication system of the aircraft on which it is to be used.
Pacemakers and hearing aids have an excpeption... although I'm surprised to see that electric razors and voice recorders specifically do as well...
guess now i'll be leaving my 14lb 240 watt Sager 8887 grounded next time....
Hard work often pays off in time, but laziness always pays off right now.
Fact : GNAA is dying
Alright ! I was waiting for this !
In Soviet America the banks rob you!
Swore I wouldn't do this again... But what the heck, I can't find the post I put up in comp.dcom.telecom all these years past.
OK guys: Let's start from the top. Yes, I have worked on electromagnetic interference and immunity. Yep, I'm a EE.
OK: So you use your computer in the plane. Say it _doesn't_ have your favorite 802.1x card in it. It radiates, anyway. The FCC when they have people put those "Class A" and "Class B" stickers on the computer (or what all) are mainly interested in making TV receivers happy, so Channel 4 doesn't get bollixed up when you're playing Doom. However - they _still radiate_. There are frequencies from 1 GHz down to durn near DC in that computer, and they're mostly all square waves. Being square waves means that what you have in there are all the odd harmonics of all those waves. Given that things are not always happening (here a read access, there a write; munch about the processor, then do another burst read) one ends up with wildly varying frequencies all over the place. Look at this stuff with a spectrum analyzer and the right kind of antennas (yes, I _do_ do this for a living) and what one sees is hash from DC to the microwaves, normally with peaks somewhere wherever there are clock frequencies. Given that there's a bunch of clocks in a random computer, you get a ton of stuff.
The people who build electronic devices do the usual tear-out-one's-hair approach - shield what you can, where you can, and get it past the FCC's and/or the European Norm standards so one can sell the thing. It still radiates. Anything with copper and moving electrons _will radiate_.
Further, anything with copper will also _pick up_ this stuff as well. One passenger is mucking with his comp; the person next to him has a gameboy. The gameboy picks up some of that radiation, rectifies same in the ESD diodes built into the ASIC's, and you get _more_ radiation. At strange frequencies.
Now, consider ye airplane. I've worked on planes (ex USN here). Yep, they're shielded. The military has some really strong specs on interference with flight nav (something about a British Tornado getting knocked out of the sky by a TV tower one day...). But I can guess how the manufacturer's test - you put the airframe in an EMI facility, turn on the radios inside, look for anolomies, turn on radars, look for more, and so on. Nickle bet that every switch in the cockpit gets flipped one way or the other, so that when that airplane ships, it's been tested so the IFF doesn't knock out the intertial nav, the VHF radios don't knock out the weather radar, and all that stuff. There's lots.
So: The airframe gets shipped. The passengers file aboard and sit down. Kids whip out CD players, adults whip out gameboys, people whip out whatever imaginable piece of electronics one can imagine, including that pedometer on your waist that >can't>moving>just>each other>probably going to affect the airframe navigation. And, if you're 30,000 feet up in the air, it probably won't matter that the airplane is 100' high or low. But, given the situation, do you really want to find out what's going to go strange on final approach at 11 p.m. in a rainstorm? Or even 2 in the afternoon when it's sunny? Augering an airframe into the ground isn't that much fun.
I am not an Electrical Engineer, but how in the world is RF leaking out of the windows going to be worse than flying over a Cell Tower at 2000 feet? It just seems to me that a Tower would be pumping out more signal than a hand held device, which would have a greater effect on signals being recieved by the aircraft.
I know I was personally on a flight into IAD when the pilot got a low altitude warning, and he blamed it on Cell Phone usage. At the time we were at 2000 feet, coming over Sterling towards the potomac (coming from the south, turning to land from the north). It was United, so I got the added bonus of listening to the Air Traffic chatter until they cut if off.
It really makes me wonder how much of this stuff (avionics) is tested.
--WooooHoooo--
Its not just planes that are susceptible to interference. Medical devices are potential prone to interference. Medical measuring devices are sensitive to interference. And if those devices are used to control therapies or medical devices, that interference can lead to unanticipated results. See http://www.ce-mag.com/archive/2000/novdec/kimmel.h tml for a long detailed article about this issue.
The problem with EMI/RFI, for both aircraft and hospitals is that it is so capricious in nature. The exact properties and positioning of the transmitter combines with the exact configuration of the surrounding environment to create potential high near-field RF intensities that just might induce currents or coronal voltages in the wrong place (in the case of aircraft , it doesn't that airplanes are nice metal tubes that help RF energy bounce around inside). This is why the FAA takes a "better safe, than sorry" approach to rule making.
Two wrongs don't make a right, but three lefts do.
what about the possibility of terrorists carying onto a plane a jammer that jams or interferes with the electronics on a plane?
Yes, but doesn't it suck when you are on one of the 25 planes that has an 'incident'?
I personally don't mind not having cell phone contact for a few hours (flying domestically, that is). Americans also tend to speak really loud into their phones, and that would be annoying. I like planes kept quiet for sleepers like me.
Maybe a burst connection for 5 minutes every hour for people writing emails. And if the airlines charged a lot per KB, it would help on the continual fight against bankruptcy.
The FCC stopped enforcing RF radiation rules a long
time ago. Good shielding and bypassing of RF would eliminate unintentional radiation and it's a cheap
thing to do.
It's time for the FCC to jettison the lawyers who screwed things up and bring back the engineers.
> We should be testing the avionics of planes to see if they can take RF of the differing frequencies
:)
> that could bother it. If it can't, the plane should be grounded until it can be hardened to handle the RF.
Watch the economy fall apart until that happens. Watch the already-bankrupt airlines not have enough money to get their fleets back in the air. Watch the rest of the world laugh as the US freaks out and over-reacts (again) instead of taking a few simple measures (like shutting off cellphones and using hand-held RF detectors).
> RF hardening is a science that the military industrial complex is quite apt at.
When commercial airlines can afford to spend a BILLION DOLLARS on an airplane, we'll let you know. Don't call us, we'll call you...
> its quite possible to bring a laptop on a plane that can fake signals and jam avionics
Your argument would be more persuasive if you didn't insist on making up garbage like this with no supporting evidence.
Did you even read the summaries of the article, much less the article itself? Laptop != dead airplane. At most, portable electronics cause very minor disruptions that can on rare occasions be a contributing factor to an accident. A terrorist trying to rely on using a laptop to bring down an airplane would have better luck convincing everyone to suddenly look out the left windows all at once.
Why don't they just have flight attendants walk up and down the aisle with a gaussmeter? If a device emits too much EM radiation then they can tell the passenger to shut it off. Otherwise they can let everyone use their devices.
I've never really understood all the crap about interference -- everything I've heard from the airline employees sounds like a voodoo-level understanding of electromagnetism. Cell phones are a problem? Then how come the use of cell phones by people outside the plane (both the phones themselves and the base stations) don't interfere? Radios are a problem? Then how come the actual radio broadcast signals don't interfere?
The main sources of serious RF noise on a plane are going to be the engines, which will dwarf damn near anything a passenger might bring on. I mean, come on -- jet fuel combustion versus a CD player??