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Science

Cell Phone Usage on Airplanes == Bad Idea 261

Posted by Hemos from the actual-evidence dept.
gclef writes "The New Scientist is reporting on a study done by the UK's Civil Aviation Authority that shows that older planes can't handle cell phone emissions. Hackernews has a little commentary on this as well. Good to hear that the newer planes can handle this, but why the heck were older planes *not* build with Faraday cages and shielded wires? Scary...." Look a ways down the page for the HNN piece - but at least now I know that this isn't simply one of the arbitrary rules that the airlines setup.
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Cell Phone Usage on Airplaces = Bad Idea More

Cell Phone Usage on Airplaces = Bad Idea

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  • well, GPS approach is becoming more widespread (Truckee-Tahoe even has one, and they don't have a tower!) and ILS isn't used as much. only /slight/ problem with this is that GPS approaches tend to be locked into the flight computer and done automagically (well, this is how it's set up in our 414, anyways), which makes it even MORE of a problem if there's interference.

    do you know if GPS is as suceptable to this sort of interference? (given the flight-charts-on-the-laptop (not to mention civ:ctp on the other laptop, or the TV, or the VCR, ...) as well as the use of GPS approaches, I'd guess that they're shielded with this sort of thing in mind)

    Lea
  • There was an article in the WSJ a while back about the whole air cellular thing. It covered the FCC vs. FAA regulation, the lack of any evidence ever of a cell phone or computer interfering with a plane, etc.

    One thing they mentioned is that those egregiously expensive AirFones are just cell phones with the base stations farther apart. For that we pay 10-20x higher fees.

    However if there is some heretofore undiscovered interference found, then we logically should refuse to fly on airlines with AirFones, no?

    Let's all stand by and watch while each airplane is grounded for re-testing. Until that happens I'll take this with a grain of salt.
  • I hate cell phones in total. No one has even proven they are safe, except for the "tests" the cell phone companies have run, which by the way are not sufficient, and just a tidbit to leave you thinking about. While nothing has shown that cell phones CAUSE cancer (yet), cell-phone users that got brain tumours/cancer/whatever have a tendency to get the disease on the same side of the head they hold their cell-phone on, and there are quite a few cases where the tumour was in the shape of the cell phone, exactly where they usually hold it! Think about it. Is it worth the risk?


  • I'm reluctant to admit to such a flagrant act of nerdiness, but, here goes: :)

    My last airline flight happened about a month ago. I thought it would be neat to take my new portable hand-held shortwave radio with me on the plane to see if I could pick up the transponder on the aircraft's black box(es), or maybe some of the cockpit/tower discussion. The flight was pretty much empty (I always take the red-eye) so for about an hour, I sat there with my earphones on and my antenna pitched up and scanned the whole damn plane from 1 Mhz all the way up to about 400 Mhz or so in short, medium, longwave and FM.

    I didn't find anything recognizable. I was seated far enough away from the engines to rule out any interference, and the whole spectrum was peppered with odd little noises generated by the aircraft (This was a Boeing 767-300 if I remember correctly) but nothing resembling any sort of communications. Considering the fact I was seated in a giant metal tube, I can also rule out ambient interference. There was a guy with a laptop about 10 rows up, and I could pick up his machine pretty easilly. Anyway, no luck.

    Most analog cell phone transmissions occur between 800 and 950 MHz. Youre going to have a hard time finding a scanner than will allow you to listen to that range. If I remember correctly, there was a law passed in '93 or so which made it illegal to sell scanners with capability in that range, in order to protect the privacy of analog cell phone users.

    You wouldn't believe the stuff I heard. People's conversations get sorta...weird after 9PM. It's a sick world. :)

    Bowie

    PS.. No "You didn't hear anything in the cockpit because the crew was asleep" jokes, please. :)


    Bowie J. Poag
  • One of the first things they teach you in flight school is that interference caused by cell-phones can cause navigational radio instruments such as the VOR and ADF to go haywire or be a little off...
  • Actually, most of the cost of aircraft-certified *anything* is in the form of "prepaid liability". Whether its commercial or private, the lawyers will go after every manufacturer of every component in an aircraft in search of deep pockets in the aftermath of an accident.
  • I'd be curious to see studies, or even numbers on this. I know that devices must meet certain FCC radio emissions standards to be sold for home/office use. Does anyone know what those are?


    --

  • Well, I've always thought that cell phone usage in cars is a bad idea, but on airplanes?? Pilots should certainly not be allowed to use cell phones.
  • Nice idea, but I don't think so.

    If a technological solution is decided on, it means either every aircraft used for MPT (Mass Public Transport) or every cell phone will need to have something done to it. Neither is going to happen.

    Which is why there needs to be a legal solution. After the first few people get locked up/fined large sums of money, the public will get to know the airlines mean business.
  • But I'd really like to see a study about laptop computers

    Dunno about "a study," but there are laptops certified for use on board commercial/passenger aircraft. (As I recall, it's a combination FCC/FAA thing: the FAA says "if it meets FCC code such-and-such, it's okay.") I know, because my former employer had to buy some for cockpit use.

    However, the POI for that airline still has to sign off on that particular model, etc., so it isn't as if you can walk on, as a passenger, and say "See the sticker? This meets code!" and expect to be able to use it.

    Of course, one laptop manufacturer cheerfully explained that although all of their laptops would meet code, they only had the rugged-built (and, more to the point, expensive) models actually certified as such.

  • On commuter flights, the takeoff/landing blackout comprises most of the flight.

    --

  • Actually, lots of people use a cellphone close to two hours a day (not me, I still refuse to get one - I have a CB (and a flare gun) in my car for emergencies, that's good enough). Think of the sales and marketing types who are running around, travelling, etc... The company picks up the bill for that phone, and it's more mobile than the one in the hotel room anyway. Waiting for a meeting - 5-10 quick minutes. Family calls you... etc. And now there's those ad campaign pushes to "Make your mobile phone your only phone".

    I think it's alright - generally, the people who use mobile phones the most are the least likely to be missed if they all dissapeared. I just hope they don't take me out on the road (cellphone + driving = LOOK THE ext2fsck OUT!!!).
  • Yes, I believe they will tell us that Pepsi causes cancer in a few years....
  • Because the data about the problems has been mainly unscientific. The number of variables envolved in this is really large, ie location of the passenger in the aircraft, type of phone, location of aircraft, type of aircraft, weather conditions. It's widely accepted by pilots that these things do cause problems.

    I know of a pilot who was experiancing problems which seemed to be from RF emissions from something, and suspected a mobile phone. So he had the stewards do a walkthrough of the plane and see if anyone was suing a mobile phone/computer. They didn't find anyone, and the interference continued. So he tuned the radio in cockpit to the frequency used by analog mobile phones and hey presto... "*ring*ring* Hello?" "Hi, this is James Smith calling about my appointment..". So he checked the passenger manifest, found this person's seat and asked "Can I have a look at your mobile phone?". The guy handed it over, pilot said thanks and handed back the phone, sans battery. The person had been delibrately hiding the phone when they were searching the plane.

    Idiots abound in the body of an aircraft :-)
  • What would happen if about 100 hackers all got some old cellphones, rigged them to some of the key frequency, and all powered up and used them at the same time?

    Wouldn't that be cool?

    Talk about surfing ... your seat cushions could be used to keep the sharks happy!

  • Yes, I believe they will tell us that Pepsi causes cancer in a few years....

    I think Pepsi One can actually cause cancer in a matter of days. Maybe not, but tasting that crap is just as bad as cancer.

    MacSlash: News for Mac Geeks [macslash.com]

  • A common mistake, but perhaps you meant "==" instead of "=" ;-)

    Patch below.

    -core

    --- slashdot_article_orig.txt Mon Jun 12 14:11:29 2000
    +++ slashdot_article_new.txt Mon Jun 12 14:11:47 2000
    @@ -1 +1 @@
    -Cell Phone Usage on Airplaces = Bad Idea
    +Cell Phone Usage on Airplaces == Bad Idea
  • The problem with technological solutions is that they take time to implement.

    Assume for a moment that we don't have to deal with corrupt politicians appointed to head the appropriate government agency (FAA to do the actual orders, FCC to provide technical backup, CIA/NSA/DIA/FBI to provide some ideas about terrorists using this for a weapon like SheldonYoung [slashdot.org] said) or the industries with a vested interest in maintianing the status-quo (lawyers, mainly). The only problem then is creating a quality solution, testing it, and implementing it.

    Let's say that we have most of a quality solution already, what with the newer planes having Faraday cages and shielding, we only need to do a little more work on the design, call it a month. Then the 'solutions' must be tested in a lab, say 3-6 months depending on problems and facilities. After that there must be tests on real airplanes. First you put cell phones, PDAs, walkmen, CD players, computers, cell modems, CBs, and what-not in a test plane (a plane with no passengers) and a flight crew of test pilots. After a statistically significant set of tests in these somewhat controled conditions, the tests are expanded to a few real flights with special test flight crews. These tests are the first with real conditions: read RISK OF DEATH of the flying public.

    I am not trying to troll or exagerate, but when you risk loss of control of an airplane, at any altitude, you risk the death of all aboard. There are usually ways to reduce risk, such as putting fly-by-wire controls in aircraft which use hydraulics, letting you switch from the wired controls to the hydraulics if the electronics go kaput when the cell phones are turned on. Eventually, you need to install the safety systems on aircraft which do not have non-electronic backups. This is the most risky step in the progression from idea to routine use; the design has been tried & tested, but there may still be a few tiny problems. Unfortunately, 'tiny' is usually easy to fix, but deadly until fixed.

    All of this means that fixes are not easy to do. However, fixes should be made. Why the FAA hasn't mandated safety devices on all airliners is unknown to me (I could guess, but ... ), but it should start a program to get a quality fix in place as soon as possible. The quality fix will be able to handle all of the current frequency and power ranges, and those which might be used in the future.

    In short, for the FAA ' ... to dump those "RF on an airplane" rules, and mandate a technological solution.' is not easy to do, and it can not be done quickly for fear of loss of life.

    Louis Wu

    Thinking is one of hardest types of work.


  • ...would a cellular phone one mile up cover thousands of cells?

    Maybe someone could post something about that. ;-)

    ------

  • Aircraft navigational systems vary in frequencies
    and sensitivity. The real headache here could be
    for a category IIIa ILS approach. The localizer will use something in the 108-114Mhz range, but
    the glideslope is UHF.
    Instruments like the ADF are sensitive to any
    strong (And some weak) electronic signal, and will
    swing to point to the strongest source of RF
    emissions that pass its filters. Won't necessarily
    be a cellphone, but you never know.
    For me, a more convincing reason never to use
    Cellular phones, or allow any passenger of mine
    to do so would be:

    As per FAR (15 CFR) 121.305:
    (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 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.

    And per 91.21:
    (a) Except as provided in paragraph (b) of this section, no person mayoperate, 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:
    (1) Aircraft operated by a holder of an air carrier operating certificate or an operating certificate; or
    (2) Any other aircraft while it is operated under IFR.
    (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 operator of the aircraft has determined will not cause interference with the
    navigation or communication system of the aircraft on which it is to be used.
    (c) In the case of an aircraft operated by a holder of an air carrier operating certificate or an operating certificate, the determination
    required by paragraph (b)(5) of this section shall be made by that operator of the aircraft on which the particular device is to be used.
    In the case of other aircraft, the determination may be made by the
    pilot in command or other operator of the aircraft.

    Or.. whatever. :>
  • Its not an issue of if its bad for the aircraft, Trust me on that, 10 Years in the military as a aviation electronic tech. Cell phones don't put out enough power to be a problem, what does happen is they are "Line of sight" transmitters and receivers, when you are on the ground and use a cell phone it talk's to 4 or 5 towers to figure out who has the best strength, when you are in the air its thousands of towers, all those towers talk to each other and so forth, all to figure out who has you the best. To the guy in the air it's a one second delay but to the people on the ground it could be a lot more. My two cents.....
  • The field strength is inversely proportional to the square of the distance. A one milliwatt transmitter at a distance of 10 meters has the same field strength as a 1000 watt transmitter at a distance of 10 kilometers. This means that nearby emitters can easily jam navigation receivers that are receiving distant navigation beacons.

    p = transmitter power
    d = distance
    s = power flux density

    s = p / (4 * Pi * d^2)

  • shouldn't it be "airplanes"?
  • Check it out here [userfriendly.org]

    --buddy
  • ...on a plane (after takeoff) and I've never been able to get any service. I have a feeling results would be very poor even if allowed.

    --- Speaking only for myself,
  • I suppose that's what the Big Men Upstairs should have told us now, right?

    but they didn't.

  • is that kind of like people trying to look cool and destroying their lungs and giving themselves cancer by smoking?
  • Correct. Also, the FCC's definition of 'cellular telephone' only includes phones than transmit on the original cellular frequencies of 800mhz.

    Newer 1900mhz phones are not covered by this regulation. (however an airline can still require that you not use them.) I'm a private pilot, and have used my 1900mhz PCS phone on a few occasions from the air in a Cessna 172. I've found it can be difficult to get a good signal however.
  • Just a small point about this. If they are banned, and if the air crew can be on the lookout for violations, that will reduce the useage to one or two units.

    Now I assume cell phones use Collision Detection networking methods, hence the more phones the noiser the airwaves get. If we reduce this to a few, it's less dangerous, hopefully to the point of being almost 100 percent safe..

    And as someone else said. The nice guy sitting up top/in front in the left hand seat has done a lot of training to be there. He knows his plane VERY well. If he isn't sure about you using your cell phone, I don't think it's worth the risk..

  • I have read an article (from Finnish magazine) that real reason to avoid Cell Phones on aeroplanes is that basestations on ground can't handle cellular phones on air.

    If you are flying high enough, your phone receives too many signals and it can't handle that. Also many basestations are using same frequencies in different locations and on air you receive many of those same time.

    Also basestations can't follow your phone if you fly fast enough. Cell phone selects always best basestation which signal strenght is highest. And on aeroplane signal strenght varies a lot.

    [ Advertizing Banner Here ] dUb(at)lumi'dyndns'org
  • Uhm, because people will quite often talk a lot louder into a cell phone than they will to a person who is sitting next to them (he says rather sheepishly).
    --
  • All electronic devices create interference, but I thought that problems in using a cell phone were caused by a system that get's confused by a ambiguosus position in relation more than one close ground stations. Live and Learn. And the smoking restriction wasn't caused by the reduction of costs in air conditionina, no, it was the the wealth of costumers.
  • Two reasons:
    1) People talk more loudly on the phone than face-to-face. This is partly an unconscious reaction to the lack of non-verbal commmunication, and partly due to the fact that it's difficult to hear what's being said for both parties to the conversation.
    2) There's nothing more frustrating than hearing half a conversation.

  • Holy crap. If that's what cellphones do to you, I'm handing mine back!
  • If you want to get an idea of HOW BAD a portable device can emit interferrance, find a cheap TI calculator (you know, the one's kids these days use in the 5th grade).

    Turn it on.

    Set it next to a cheap radio receiver. Turn on the AM band. Flip around the dial until you hear a wierd regular pattern. Play with the calculator. Notice how the pattern changes as you play with it.

    This is a cheap calculator with a "processor" less powerfull than an 8088. Being powered by a watch battery.

    Do you honestly think that your laptop -- with it's lithium ion batteries powering a Pentium III/500, hard drive spinning at 7200 rpm, multiple fans, LCD screen with fleurescent backlight -- produces LESS noise than a freek'in calculator? Yeah, they're shielded; but the shielding isn't THAT good, just enough to keep it from interferring too much with your portable phone.

    (shoot, if you knew how much noise an electic motor alone made you wouldn't bring up that question...Electric RC cars have severe problems with noise from the motor if a few things arn't done to mitigate the problem [add a few capacitors in spots to eat up the sparks, basically]).
  • AM is used by aircraft because the strongest carrier signal is heard, so even if someone sits on a microphone, the tower can still talk to other aircraft.

    False.

    FM modulation results in "signal capture" i.e. the strongest signal gets through. With AM what you get is "heterodyning" [look it up] which results in an annoying squeal for everyone listening on that frequency.

    Pilots know this very well, since ATC communications are AM. Every now and then two people will speak together (referred to as "stepping on someone else") followed by someone saying "Blocked" or similar.

    AM is bad for blocking interference also. You can hear thunderstorms on AM radio.

    A very common problem with electronics close to each other is the front-end of a receiver getting overloaded by a strong RF signal. With a mobile phone this is unlikely but possible - and as someone else said, aircraft radios were never certified against mobile phones and their frequencies.

  • Here's a few articles that point out there's a tenuous relationship AT BEST between cell phone use and brain cancer. No really hard evidence at all... from the New Australian [newaus.com.au]

    an article from the Wall Street Journal at junkscience.com [junkscience.com]. I like the last paragraph of the article that says: "Car accidents resulting from using a cell phone while driving are 'much more of a problem at this point' than radio emissions".

    Another good one from junkscience.com [junkscience.com]

  • Even though you weren't transmitting with your radio, it could have interfered with airline electronics. That's why portable radios are not allowed to be used _at all_ on flights--they are banned by the FAA. IIRC, they have various oscillators that can interfere with many frequencies directly and many indirectly through harmonics.

    An old IEEE article in Spectrum from a couple years ago discussed this.

    -core
  • The Civil Aviation Authority's press release [caa.co.uk] and the full report in PDF format [caa.co.uk] are available from the CAA website (www.caa.co.uk [caa.co.uk]).

    TomV

  • Again, I do not speak for my company
    AFAIK, GPS navigation is not really widespread. None of our aircraft have it.
    GPS naviagation requires a correction signal transmitted from the ground to the air to compensate for GPS error (both artificial and natural error). The idea is to survey the exact location of the end of the runway and install a GPS receiver that listens to the GPS signals and transmits GPS error compensation data.
    GPS Navigation will never replace existing methods. Nor should it - redundency in navagation data is good. Of course, if the data do disagree, which version of the truth do you want to go with. Until somebody dies and the NTSB concludes GPS would have prevented it, it isn't likely to be mandatory.
    Commercial aviation tends to be highly regulated and the FAA inspectors tend to be reluctant to allow airlines to change procedures and processes when the operating carriers have good safety records. Everything in flight is scripted.
    What will put GPS in commercial aircraft is something called "Free Flight". Aircraft don't flight straight from point A to point B. They follow a connect-the-dots route with NavAides every one to three hundred miles. These form highways in the sky. Free Flight will allow aircraft to "Off Road." With a proposed implementation arround 2006, this will take a while.
    Another impediment is there are many carriers with aircraft fleets older than the average Slashdot reader. (FYI - not mine.) There isn't anything to plug a GPS into.
    Cheers!
  • Why is driving while talking on a cellphone dangerous? Is it because it involves the concentration of listening and talking? In that case, why do you not also complain about people talking to their passengers? Or is it because it occupies a hand? Why then do you not complain about people who only have one hand who drive?
  • El Al, widely regarded as having the tightest security of any carrier provides some insight here. Bags are checked by machine for every passenger and by hand for many. In addition, some unsmiling individuals will ask you a series of questions about your luggage. And yes, they are adequately trained for this...don't even think about lying. It's scary and it's effective. Doubtless there are other technological measures in place behind these scenes--rucksacks are tamper-sealed once checked, for a start. But it's the quality of the questioning that's key to security.

    When I was 11, I went with my family to Israel. The security guy asked my father if we'd ever been before. I piped up "no", not remembering that we'd been as a toddler. Not only did I get a look that stopped me from saying anything else till we were ground-side in Israel, but we were also delayed for 20 minutes while they checked things out more thoroughly.

    The human factor is the key factor. There are rumours that background checks are carried out on every passenger on an El Al plane (including the ultra-Orthodox guys with the beards and black hats) before you fly and that there are security agents on every El Al plane (in plane clothes) and all over the airports. It's certainly true that they have no qualms about letting you miss your plane in order to question you more thoroughly.

    Is it painful? Yes. Does it cost El Al a fortune? You bet. Do you feel secure flying with them? Yes indeed.

    [Side note: I flew with BA to Israel not so long ago. The same unfriendly faces were asking the same questions -- so it's likely that at least half the security measures are required / implemented by the government and not El Al.]

  • Re:An accident created the regulation (Score:3)

    by phliar ( 87116 ) on Monday June 12, 2000 @03:55PM (#1007628) Homepage
    The local oscillator leakage caused a false indication on one of the ILS (Instrument Landing System) instruments (I think it was called the localizer).

    Localizers use frequencies around 110 MHz. Consumer FM receivers use a first intermediate frequency (IF) of 10.7 MHz. What this means is that if you tune an FM radio to KOZY 101, the radio transmits noise at 101.1 + 10.7 = 111.8 - which is bang in the middle of the navigation band.

    Fortunately, all commercial jetliners now use inertial navigation systems, so this particular failure mode is much less likely.
    Inertial is not used for approaches, only for en-route navigation. The problem with inertial systems is that they drift, so the longer you've been airborne, the more inaccurate they are. An error of about a mile is no problem up in the stratosphere, but you can't be a mile off the runway when you touch down...

    Right now ILS is the only precision approach available in the vast majority of cases. Once the FAA puts up WAAS and LAAS augmentation for GPS, aircraft can use GPS for precision approaches.

  • ). The VHF aeronatutical band is just below the commercial FM band, by the way.

    ObNitpick -- it's above the FM band.

  • There are all sorts of problems with radio receivers as well. ... The bigger problem comes from a powered heterodyne radio receiver. [nice intermodulation discussion snipped]

    Heterodyne receivers aren't the only problem. The current-generation of power transistors are rather wideband and can up/down-convert signals. These transistors are found in DC-DC converters, notebook backlight power supplies, hard disk motor drivers, and so forth. Most gadgets larger than a Palm have some sort of switched power circuit in them. The transistors aren't as wideband as those in radio receivers, but they can still cause problems.

    This isn't theoretical either. A while back, we had to diagnose an odd problem with a pager system. There were actually two paging transmitters, and two sets of pagers, on different frequencies about 60 kHz apart. Occasionally, one set of pagers would receive something that had been broadcast on *the other frequency*. It turned out to be a computer monitor: the RF from one transmitter was getting into the monitor, being mixed with the ~60 kHz horizontal frequency, and reradiated 60 kHz up and down from the carrier. You could tune the effect by going into the Windows settings and changing the refresh rate. We engineers all thought it was pretty funny. The users, of course, were less amused.

  • Cell phones put out about 1 W of radio power. In typical circuits, that means about 5 volts of signal. That's more than enough to upset many circuits.

    So why not just shield everything? Because shielding is expensive and unreliable. The New Scientist article referred to "Faraday cages", but that's *grossly* inaccurate, since a Faraday cage only provides electrostatic shielding (by surrounding the circuit with metal). Real shielding involves seamless metal enclosures. The important thing is *seamless*. Suppose you have a perfect seamless metal box. It's a perfect Faraday cage and a good radio shield -- cell phones will not interfere with anything inside it. If you cut a narrow 0.1mmX15cm slot in it, it will still be a very good Faraday cage, but it will be a *terrible* shield. Radio waves will "shine" right through, despite the narrowness of the slot.

    And in the real world, seams and slots are hard to avoid. If a panel isn't properly screwed down or has the wrong type of gasket, radio waves will go right through. If someone yanks on a shielded cable, the shield can invisibly separate within the connector, and actually end up worse than no shield at all. So you just test the shielding, right?. Wrong! Shielding is almost impossible to test. Short of *laboriously* testing every single box and cable with a signal strength meter, you can't test shielding. I would guess that testing all the shielding in an airplane would take a few hundred hours of a radio engineer's time. Nobody could afford to do that on every plane every few years. Since shielding is *never* perfect after a few years of service, and you can't really test it, it's prudent to ban powerful transmitters in the plane.

    I also suspect that the superstructure of the planes act to channel the signal along the length of the plane rather than merely radiating uniformly out from the plane itself.

    Absolutely correct. The metal structures of the plane will guide the radio energy to surprising and unpredictable locations. The upshot is that a cell phone in the front of the passenger cabin might send much of its power to an electronics unit at the back of the plane. With radio waves, power doesn't necessarily drop off much with distance, especially in a reflective environment. If you allow a 1 watt transmitter anywhere in the plane, you have to design the plane to withstand 1 watt delievered anywhere.


  • Egads. Didn't know that..I thought it was only for takeoffs and landings that such rules applied. So much for scanning for the transponder on my return flight. ;)



    Bowie J. Poag
  • Okay, my only question is - who's so damn important that he/she/it has to be in constant communication during an airplane flight? Criminey - can't people just relax and have a $10 cocktail and enjoy an in-flight movie? Or (gasp) read a book? Who needs to be connected ALL the time? Probably the same self important twits who try and conduct business while whizzing down the freeway at 87 miles an hour.
  • The study is clearly double blind study by disinterested parties, and from the way it was conducted, it seems like the folks were simply trying to get ammunition for supporting their beliefs. In fact, from the article, it appears that many of their conclusions are based on a lot of inference.

    In any case, if airplane safety is threatened by radio transmissions in the milliwatt (PDAs) and hundreds of milliwatt (cell phone) range, there is clearly something wrong with the design of those airplanes and navigational systems. Those planes need to get grounded and upgraded. That's both because passengers won't stick to the regulations, and since an adversary can trivially build tiny devices that emit lots of power and disrupt a large part of the spectrum.

  • That should be "the study is clearly NOT a double blind study by disinterested parties"...
  • A cell phone on the ground has line of sight to maybe 2 cell towers at a time. Maybe 3 if you're downtown.

    My phone is seeing quite clearly three tower where I am right now, and I'm in a small town. In high density urban areas, you quite often have more than that.

    Just immagine the cell tower selection algorithim with an input size of 4000 possible towers.

    You are correct that using a cellular phone in a plane causes all kinds of trouble, but this isn't the reason. Remember that cellular systems rely on channel reuse to achieve high capacity. In other words, if channel x is used on tower A, it can't be used on any of the neighboring towers, but it can be used on towers that are further away. The assumption is that with the right power tuning etc, the two towers won't interfere with each other since they are not next to each other (of course sometimes if the network is too dense there are trouble spots where this isn't the case, hence crosstalk). This assumption is based on the fact that users are close to the ground. As you said, when you are in an airplane your cellular phone can see many towers, some of them using the same channels. I'm not sure how a network would respond if one of its channels was used from a phone in a plane, but I imagine that after all the users of the channel suffered from crosstalk for a while, they would either lose their calls or handed off to another channel, rendering one channel useless in a large area. Just a few people using their phones in a plane would have a devastating effect on the capacity of the system underneath, especially if flying over a large city. Not to mention that if your provider has any fraud detection system in place you would probably trigger an alarm by appearing to be in more than one place at the same time.

  • He's talking about the same studies you were.

    Ask any experimental scientist or statician about the difference between establishing a correlation and establishing causation. please.

    Critical thinking 101, people.

  • Yeah, I knew that. I also know that the skin of the planes are designed to direct & disperse the energy from lightning strikes to element which are supposed to be able to handle the charge.

    But I'm also thinking that the plane isn't a perfect Faraday cage (otherwise you wouldn't be able to hear radio signals from a walkman in the plane) and that the energy of the broadband EM radiation from a lightning strike is going to far exceed the puny 2 watt output of a typical cell phone.

    Even if every single passenger on the plane was talking on their cell phones all at once, would it even come close to the electrical disturbance caused by a lightning strike?
  • I want to give another example of why every computer user should read the Forum on Risks to the Public in Computer and Related Systems [ncl.ac.uk].

    While I recommend it to everyone who uses computers for anything of any significant importance, it is especially important to those who:

    • Design computer systems, such as software and hardware engineers, and
    • Make policy decisions involving computers, such as managers and government officials
    This post to comp.risks [comp.risks] ought to put the fear of God into most computer users and suggest that us programmers need to work hard to take responsibility for our work:

    I recently received a legal document as part of a personal negotiation that I am doing. The document was e-mailed to me in MSWord format. As I was showing it to my lawyer (who happens to be my wife), we decided to put our thoughts inline using the track changes feature of word. After selecting Tools, and Track Changes, we clicked on "Highlight changes in document" and voila, suddenly a whole bunch of red appeared on the screen. We looked at it closely and realized that everything in red represented changes in the document that my counterpart's lawyer had written. We got a good look at the previous version of the contract, as well as a bunch of comments and justifications that the lawyer wrote to his client. It was an eye opening experience.

    It appears that instead of selecting "Accept all changes" before sending it to me, the other party to the contract simply turned off the highlighting to the track changes feature.

    This is obviously a case of an unsophisticated person misusing a feature. However, it is very dangerous. Lawyers send word documents around all the time, and many of them do not really understand all the features that they use, nor should they have to. I imagine that I was not the first person to see some behind the scenes conversation in an important word document, that I was never intended to see.

    I bring it up in this discussion of cell phones and aircraft because electromagnetic interference in safety-critical systems is a frequent topic on Risks. For example,

    On 26 Feb 1998, WFAA TV (Channel 8) in Dallas turned on their new digital HDTV signal. As a result, 12 heart monitors stopped working in a Baylor University Medical Center heart surgery recovery unit; they happened to be on the same frequency. The monitors were made in the mid-1980s, and were slated for replacement. [But the patients weren't?] In the interim, WFAA has stopped transmitting -- because there are no commercial receivers yet anyway. [Source: * Dallas Morning News*, 5 Mar 1998. PGN Abstracting]

    If you're upset about the sorry state of software these days, there is in fact a lot that can be done about it. Get started by reading Risks [ncl.ac.uk].

    Mike

    Tilting at Windmills for a Better Tomorrow
  • Here is an article on the subject. The conclusion: Yes, they do.
    Do portable electronics endanger flight? The evidence mounts
    - Perry, T.S.; Geppert, L.
    This paper appears in: IEEE Spectrum
    On page(s): 26 - 33
    Sept. 1996
    Volume: 33 Issue: 9
    ISSN: 0018-9235
    References Cited: 2

    Abstract:
    According to a new study, the risk that RF emissions from carry-on electronic devices will affect avionics, although not high, is still high enough to warrant tougher government regulations. The authors discuss a study by RTCA on the problems of interference caused by portable electronic devices (PEDs). The electromagnetic emissions from PEDs and their effects on avionic systems, particularly radionavigation and communications, are discussed. Some of the PEDs and the types of problems that they can cause are then discussed. The regulations covering this issue are outlined.
  • Yeah, this is one of those things that I wouldn't put too much stock in, that cell phones cause brain cancer.

    It seems it's one of those things where people are trying to find something to blame.... and they'd do anything to believe in it. It's just like when people say that "living close to power lines" give you cancer.

    I mean, think how many people have cell phones, almost everyone. Now, those people who have brain cancer, and use a cell phone, would like to blame the cell phone.

    Hey, lets go..
    SUE MOTOROLA...
  • ...on an airplane. A cell phone on the ground has line of sight to maybe 2 cell towers at a time. Maybe 3 if you're downtown. From an airplane 30,000 feet up, you're phone's sphere of effect just got huge. Just immagine the cell tower selection algorithim with an input size of 4000 possible towers. Add to that the fact that you're going several hundred MPH and you'd be changing towers every couple seconds. You're looking at a distributed system nightmare. And there's FCC regulations that prohibit you from using your phone up there too.
  • Peter G. Neumann [sri.com], the moderator of the Risks Forum [ncl.ac.uk] wrote a book called Computer Related Risks which draws on the material from the forum and discusses it in more depth.

    It has ISBN 020155805X and you can purchase it online from:

    If you teach a course in programming at any school, I suggest you put this on your "recommended reading" list, and if you teach a course in embedded or fault-tolerant computing, I suggest you include it in the required reading.

    Mike

    Tilting at Windmills for a Better Tomorrow

  • Sheesh! (Score:2)

    by pkj ( 64294 )
    I hope I'm not the only one that is pretty freaking scared that the relatively miniscule output from cell phones can effect the electronics of a commercial passenger airliner.

    Kind of makes you wonder what could be done with a much more powerful transmitter easily disguised as a small am/fm radio, or even a land-based directional transmitter...

    -p.

  • Assuming that there is no safety issue with using cell phones on airplanes, and forgetting for the moment the legal issues, what about the technical issues?

    Sure, lots of people would love to use cell phones when the plane is on the ground waiting to take off or heading to the terminal, and that should work fine, but what about at 30+ thousand feet at 600mph? You would be changing cells every minute or two. I doubt coverage is adequate, even if there's no problem with the range.
  • Okay, so for how many years have we been hearing warnings against using electronic devices on airplanes?

    Why has nobody run such a test until now?

  • The regulation was originally put into place because of the strain that airborne cell phones put on the cell phone infrastructure.

    When you're on the ground, your cell phone transmissions are being received most likely by anywhere from 1 to 6 cells or so. When you're airborne, that number jumps dramatically...into the thousands maybe?

    The original regulation was put into place because, at least at the time, it was quite a strain on the cell phone infrastructure to sort out which cell would handle that call. Arbitrating this access between 5 or 6 cells isn't too terribly difficult...arbitrating it between thousands, well, that gets computationally expensive. :)

    I don't know what the current state of cell infrastructure is, perhaps the systems could more easily sort this out now, I'm not savvy in that area, but anyway, that's the original idea.

    Jeff
  • If you MUST make a call, there are phones you can use on the backs of the seats. So they cost a little more. boo hoo.

    --
    grappler
  • why the heck were older planes *not* build with Faraday cages and shielded wires?

    Well, in 1989 (equipment built before then has the problems, according to the article), a 'mobile' was about the size of a housebrick, was incredibly expensive to operate and didn't roam awfully well - so taking it abroad, or operating it on a plane, was something that was never envisaged.

    It's easy to ask such questions with hindsight, but what would you have said in the mid-80s if someone had told you that mobiles in 2000 would be smaller than a cigarette packet, and would work practically anywhere in the world?

  • Violation of FCC regs (Score:3)

    by AJWM ( 19027 ) on Monday June 12, 2000 @11:11AM (#1007716) Homepage
    It's a violation of FCC -- not FAA -- regulations to use cell phones aboard aircraft because of the transmitting range at altitude. Your signal covers more ground, giving greater potential for interference and confusing the multiple cells you're overlapping. FCC couldn't give a rats behind if it happens to screw up navigation equipment too. (Well, except where that nav equipment is also based on radio signals.)

    Now, the FAA and airlines may also have a legitimate beef, and maybe even some regulations, but it's the FCC who will slap you with a heavy fine if they catch you doing it.
  • Not really. There are tens of millions of wireless subscubers in America, how many are going to be in the air 'sucking up bandwidth'?

    Cell phones only tune to one control channel at a time. When you are leaving the coverage of one cell, the network tells your phone which channel to switch to to get the next radio.

    Don't think it would cause the collapse of the cell phone network, mmm k?
  • Most analog cell phone transmissions occur between 800 and 950 MHz. Youre going to have a hard time finding a scanner than will allow you to listen to that range. If I remember correctly, there was a law passed in '93 or so which made it illegal to sell scanners with capability in that range, in order to protect the privacy of analog cell phone users.

    The next time you are in Europe, stop by a local ham radio shop. Most European countries do not block the 900MHz band for general purpose recievers. That's where I bought mine! It even has the FCC ID, even though it is not supposed to because it is not to be sold in the States. I guess the company did not want to deal with the hassle of domestic and international labels. The one label has all of the testing marks ( FCC, CE, etc ). The FCC id makes it a hell of a lot easier to get through customs. ;-)

    Yes, I have heard some very interesting phone conversations on that thing. Also, don't be chattering away too freely on your digital phone either. I know a guy who was a tech at the local wireless utility, and he had access to a nice little device which he could use to track CDMA calls. I am very careful about what I say on ANY phone network after that. It's too damn spookey listening to people converse like nobody is around. I feel like a ghost! BOO!


  • What about the social aspects of cell phones?

    I was on a train from Boston to New York (the new Amtrak Acela service), and for half the trip, the person in the seat behind me was chatting on her cell phone. That was not fun. At least at $3/minute, most people will make the airphone calls short.

    I've heard that some commuter trains now have phone-free cars. Will airplanes need separate cell phone sections? Or perhaps just a noisy section (no cell phones or babies outside that section).

  • Those Damn Airplaces (Score:5)

    by Cannonball ( 168099 ) on Monday June 12, 2000 @11:14AM (#1007743)
    You know, I'd been using my cellphone in airplaces for quite sometime now, my provider hasn't said anything about it...and I pay them $30/mo for the service! Now I'm gonna have to find a fscking vacuum to talk in? Man, the nearest one is like 15 miles from here...but I hear it's expensive to get to, and you need a pretty important patron...but I hear the reception sucks :). Fix that headline Cmdr Taco.
  • Can you provide a reference to your "recent studies"?

    Yes, I can.

  • This is contrary to other studies I've seen. (Score:5)

    by ericlj ( 81729 ) on Monday June 12, 2000 @11:15AM (#1007749)
    At the link below (which goes to TELECOM Digest V19 #457) is information which directly contradicts this newer (and apparently much smaller) study.

    I believe that the tower-switching issue is genuine, but I find it hard to believe that personal electronics actually have an effect on jets (mainly because I've been on plenty of flights surrounded by people ignoring those rules -- and I've yet to be involved in a crash).

    http://hyperarchive.lcs.mit.edu/telecom-archives /archives/back.issues/1999.volume.19/V19_% 23457
  • And they don't want any competition.
    Notice that phone in the seat back in front of you
    on the 737? The one you can swipe your card through? Even if cellular phones did work on
    an in-flight aircraft, they would not want you
    using them.

    Somebody commented that "it would be nice" if you could use your phone while waiting to take off.
    I often make a call from the plane while it's still on the ground. They don't tell you to turn them off until they "secure the cabin for takeoff."
  • I wonder if the massive expense involved in the recent move to put miniature tvs on the back of all seats in third class [...] is due to the need to ensure minimal leakage?

    Some years ago I was involved in a project looking at this kind of set up.

    The problems are huge, and EMI is actually one of the more minor problems. You mostly solve it by using fibre or good co-ax for the cable runs and faraday cages for the electronics.

    The big danger is fire. Every piece of equipment has to be certified to ensure that it won't start a fire, and if one does start that the equipment won't make things worse. Cabling is the big headache here: a cable conduit full of PTFE makes a wonderful channel for fire to spread and also creates lots of poisonous smoke. Cables need to be specially rated, as do the connectors.

    Then the equipment must be safe in a crash. No broken glass, even when a passenger's head hits it. It also must not be able to fly out of the seat and hit the person in front.

    It has to be cooled, even though the seatback component is surrounded by a good insulator. But at the same time it has to withstand Junior pouring his orange juice over it, and curious passengers with pocket toolkits (hello, you know who you are...)

    It has to withstand vibration, pressure changes and temperature extremes (aircraft may be left parked in the hot sun or freezing cold). Components are rated for this sort of thing of course, but aircraft operation tends to put you in a corner of the envelope, and failures are therefore much more likely.

    Finally you are on a strict power and weight budget.

    Overall, a challenging collection of issues.

    Paul.

  • Sure... some yahoo will probably make a point about how the two are totally differemt.

    Well... they are totally different.

    Consumer RFI is not going to throw a 747 into a spin. The danger is that it will interfere with navigation sufficiently to cause an accident. For instance, missing the runway on an ILS approach.

    A lighting strike is going to produce enough RFI, and even EMP, to interfere with pretty much anything electronic unless it is very well shielded. But its over quickly. Consumer RFI can last the entire flight.

    Paul.

  • And I thought the airlines were just making all this up so people have to pay $5/minute to use the airfone in the headrest in front of you.
  • Bluetooth looks like being an even bigger headache because lots of bluetooth devices cannot be turned off, except by removing the battery. They have low power standby states, but can be woken up, or might even wake up on their own schedule.

    Paul.

  • Okay, fine -- cell phones are radio transmitters after all. But I'd really like to see a study about laptop computers -- it's ridiculous to have to keep them turned off. Airlines even make people "turn off" their palm pilots (never mind that they don't really have an "off" setting), which can't be producing much more interference than a digital watch....

    --

  • So the cell phone infrastructure has a built-in denial-of-service attack. Float a ballon that transmits a cell phone signal at high power. Watch cell phone network collapse.

    Is it that easy?

  • Funnily enough, until recently I had laughed at the idea that mobiles would cause problems. Then, one day I put my Nokia 7110 down on my desk as it wandered off to some WAP site. I put it right beside my mouse and to my suprise the pointer started wandering across the screen. I've turned off my mobile in the terminal every time since..
  • I think when Hemos asked that question ("why the heck were older planes *not* build with Faraday cages and shielded wires?") he was wondering why you wouldn't build the planes with that sort protection ANYWAY. Wouldn't it have been smarter to protect vital aircraft systems from any potential source of interference, even if it was unlikely that the interference would be around much? It seams reasonable to me to expect that an aircraft has its vital systems protected from potentially harmful interference; after all, if it could cause the major problems they allude to in the article, wouldn't you protect the systems?

    However, I really don't know much about this type of thing; then again, I doubt Hemos knows much about wiring aircrafts either.

  • We live in a confusing mess of EM signals all the time nowadays, plus of course all the natural sources of EM radiation add a considerable background level. So I'm surprised that there isn't shielding on the critical circuitry in a plane already.

    On the other hand, the power of EM emissions from a mobile phone are orders of magnitude greater than the background levels. I also suspect that the superstructure of the planes act to channel the signal along the length of the plane rather than merely radiating uniformly out from the plane itself. This has implications for the positioning of critical circuitry in the plane itself - having such mechanisms at resonance points within the plane is going to make shielding either cumbersome or ineffective.

    But this also must have implications for the future of mobile transmissions while flying. If people wish to remain connected to the internet or phone people on the ground, it's clear that the current technology quickly runs into difficulties both in routing the wireless mobile phone packets to the mobile phone towers and in keeping a strong EM emission from interfering with systems on the plane. So will we see an internal intranet made available inside the plane with some transmission system suitable for moving data between the ground and an airliner, possibly in the middle of an ocean? I could see a system arising using satellite uplinks and maybe adding Voice-over-IP to the mix to allow incoming/outgoing calls. We're already seeing a lot of Wireless LAN technologies arriving in offices, so I wonder whether we'll see some offshoot of that technology on our flights in the next five years.

    Cheers,

    Toby Haynes

  • Agreed. The one car accident I've ever been in was when I was trying to dial a cell phone and I rear-ended some mexican lady. She proceeded to sue me, but I never found out what happened with that lawsuit since I left for college before it was sorted out. That was 2 years ago :-)
    --

  • Not just cell phones... (Score:5)

    by wass ( 72082 ) on Monday June 12, 2000 @11:24AM (#1007781)
    Also understand that it's not just the cell phone transmitters that pose the threat of interference with the aircraft's electronics. There are all sorts of problems with radio receivers as well.

    The simplest problem, and also probably least likely to affect the plane, is passive non-linear antenna radiation. Basically, an antenna connected to a non-linear passive device can re-transmit the incoming RF at sum/difference frequencies (IM distortion anyone?). Although these re-transmissions are far below the incoming RF signal strenth (and most likely the noise floor) and not likely to interfere with the aircraft.

    The bigger problem comes from a powered heterodyne radio receiver. Ie, a receiver (like a standard FM radio) that down-converts the incoming RF to an IF. The mixer on board the receiver doesn't have perfect isolation, so some of the produced IF (which is heartily amplified) will leak back through to the antenna, which can re-transmit. (FYI, a mixer multiplies the incoming RF with a synthesized LO (local oscillator) to produce output at the sum/difference of those two frequencies. Work out the trigonometry if you're bored, it's pretty cool.) Once again, the re-transmitted IF power is pretty small, but it is produced, and may interfere with the aircraft's receivers. And seeing that most IF's are in the range of 10 MHz or so, there is much opportunity for interference, almost independent of device RF frequency. This is why many radios are not allowed during flights, even if they're receive only.

    That's why the aircraft-certified electronics are so expensive. (example - compare prices of a marine GPS unit versus an aircraft GPS unit). The aircraft units have had many resources spent to properly shield them not only from incoming RF (other than the GPS signals, of course), but also for outgoing IF re-transmission.

    This IF effect has it's beneficial uses, too. For instance, one of my coworkers lost his RC model airplane when some wind gusts picked up while he was flying it. One of his friends grabbed his multi-element yagi antenna, tuned his receiver (non-heterodyning) to the IF frequency, and by scanning around (and using variable attenuators) they were able to track down the plane. Even though it wasn't actively transmitting any RF signals!

  • Terrorism (Score:4)

    by SheldonYoung ( 25077 ) on Monday June 12, 2000 @11:28AM (#1007787)
    Okay, now I'm a little concerned. Smuggling a bomb on an airplane is a very difficult thing to do. What ISN'T hard it shipping a crate of electronics equipment designed to give off a wide spectrum of high energy radio waves.

    What's stopping a terrorist from cargo shipping an electronics system designed to take down one of the older planes? How would the airlines respond with a threat to turn on such a device? Would they even believe it?

  • I'm not sure about laptop emissions (what are the clocking frequencies of every all bus lines?) Keep in mind every strip of wire, over which is sent a changing voltage or current, is an antenna. The frequencies of the digital pulses, their harmonics (and PRBS sub-harmonics), as well as the configuration of shielding and nearby conductors, plays an effect on RF generation and propogation. See my post [slashdot.org] below about the curious problems of radio receivers and spurious IF re-transmission.
  • Many of the "older aircraft" have been retrofitted with newer avionics and "glass cockpits," essentially computers which ease many of the navigational and aeronotical chores pilots have to do in various phases of flight.

    When the planes were originally designed, sans faraday cages and the like, they didn't need them, because the old, standard navigational equipment (VOR receivers, DME, ADF) didn't require them. For that matter, neither did the flight instrumentation: most of it was (and, in the smaller planes those of us who fly for fun use, still are) mechanical, using vacuum driven gryroscopes, static air inlets, a pitot tube to measure air movement (and thus airspeed). My standby vacuum system is electronic (as are the lights on the panel), but the primary vac system uses induction and works even with the electronics shut off. The plane flies just fine, and one can still navigate using pilotage (their naked eyeball).

    The newer aircraft are designed to require the fancy electronics, but even they still have the old, familiar instruments most of you know from PC flight simulators.

    There was an aircraft in Canada (I forget the model) which was landed safely after it ran out of fuel midflight and lost all flight systems, except the basic, gyroscopic instruments just about every aircraft since the 30's comes equipped with.

    Loss of navigation is only a life-threatening concern in situations of low or no-visibility, such as the middle of the ocean (which way are we supposed to fly?) or in IMC (bad, foggy, rainy weather, now we can't fly the published approach, how the f*ck do we find the damn runway?). Even then, a quick call on the cell phone to the tower can probably get you the guidance you need (which is what I would do if I lost comm while in the soup, the FCC be damned). ;-)

  • There NEEDS to be a TECHNOLOGICAL solution... (Score:4)

    by SvnLyrBrto ( 62138 ) on Monday June 12, 2000 @11:33AM (#1007799)
    ... and *NOT* a legal one.

    A number of people have pointed out that it's illegal to use cellphones on aircraft anyway. And then there're the similar restrictions about discmans, gameboys, laptops, etc.

    "RF frequency can disrupt navigation / autoland / whatever, so let's ban electronics either completely or just during takeoff / landing." Yeah... Grrreat idea!!!

    What people who say "it's illegal anyway" overlook, is the fact that there is just about always some yahoo who thinks that the rules don't apply to him.

    They'll use those tiny headphones and keep the discman in their pocket. Or they'll use a headset with their cellphone (till the plane climbs out of cell tower range). Or they'll hide the game boy whenever a stewardess gets near. Or they'll say they're using a Palm III when it's really a Palm VII. Or mabye even, they don't mean to break the rules at all, but they just leave the cellphone ON during the flight (those suckers *DO* transmit even when you're not in a call, ya know).

    You know it'll happen, no matter what laws or rules or regulations you impose, and whatever safety guidelines you publish, and no matter how many times you tell someone. It WILL happen.

    And that's why the FAA needs to dump those "RF on an airplane" rules, and mandate a technological solution.

    john

  • Let's take an example. I'm not saying this is how it is, or anything like that, but it's a possibility. An example of how studies can appear to show cause even when they don't. There are certain groups of people who tend to use cellphones more than other groups. Figuring highly in the group of phone-users are business people, the ones who are always on their phone so they can keep in touch with the home office and stay informed of any changes. These people tend to lead more stressful lives than average. High stress has been shown to lead to heart trouble. It's not entirely farfetched to say that maybe high stress can cause or at least influence brain cancer as well. And there we have a situation where there is a high correlation of cell-phone use with brain cancer, and no causal effect at all. If these people stopped using their phones but otherwise continued on with their lifestyle before (assuming all I said above was true, and I claim no such thing, remember!) then they would still be at the same risk for cancer. Now, I am not saying that the causal relationship is false. However, you need to look beyond the obvious silliness of tumors causing cell-phone use before you can dismiss any causal relationship beyond the one you seek.
  • Airplane's have windows. and doors with a gap between the fuselage. (agreed it's an airtight gap, but not RF tight). I know, because I've used my GPS unit successfully on some commercial plane flights. But I've since learned of the dangers of doing so. See this post [slashdot.org] summarizing a talk I had with my boss as to why radio receivers on planes can be bad.
  • Hmph... one should also keep in mind the lifespan of aircraft. I recently got my private pilots licence in Canada (an expensive hobby, but worth it, IMHO), and I did my training on a 1969 Cessna 172. When I got my Glider Pilots Licence the year before, I used gliders built in the 1970s and was towed by aircraft used for napalm bombing in the Korean War (1953 Cessna 305 aka L-10 Bird dog... the US used a different designation. Very cool plane... it still has the trigger on the stick). There are even airliners in use in the world that were built in the 1970s. (L-1011, old 747s, etc.) And, these are planes that are used daily. Unlike cars, they can last so long because they are well made (which is why a brand new Cessna 172 costs $150k+) and well maintained. At our local flying club, the aircraft undergo inspections of varying intensity (as required by law) after every 100h of usage.

    My point is that, at the time they were built, there was no idea that EMF could be a problem. I mean, even the radio navigation system we have in place today (and the reason you can't use electronic devices during takeoff and landing) wasn't conceived until long after many of these planes were built. At the time, most of your navigation would be by maps or, at most, very non-sensitive navigation devices (ADF, etc.). Instrument landing and the percise navigation devices required to work around JFK in the states, or even Person International in Toronto couldn't have been taken into consideration with the building of the plane.

    Hmph... additionally, cellphones are bad for use on airplanes for another reason too. At higher altitudes, you can get direct line-of-sight contact with many towers at the same time, which messes with the system emmensly (which is why it is outlawed, afaik, by both Canadian and American (FCC) authorities.

    Just my $0.02 CDN worth from experience.
    -legolas

    i've looked at love from both sides now. from win and lose, and still somehow...

  • EMF on Aircraft (Score:3)

    by PotatoMan ( 130809 ) on Monday June 12, 2000 @11:54AM (#1007820)

    The use of personal electronic devices on aircraft has been debated a lot in the literature. The issue is resonance. An aircraft cabin is basically a long metal tube. So if your laptop hard disk puts out the right frequency, the signal may be amplified and interfere with the electronics. One result I've seen (I think this was IEEE Spectrum) is that a laptop hard disk put out the same frequency used by navaids. There is no consensus on this, so the FAA takes a conservative stance.

    As for Hemos' suggestion of Faraday cages, the issue is really cost. How much more are you willing to pay in ticket prices to haul around a cage so that a few passengers can play Doom? Also, remember that the flight instruments are housed in the same metal tube, so you'd have to put a second cage around that section of the aircraft. And I suspect it is far easier to say, "put a cage around it" than it is to actually do so. For one thing, people kind of like those pesky windows...

    Weight is such a big factor that aircraft manufacturers went to Kapton wiring because the insulation weighed less. And yes, all the wiring is sheilded. But I can tell you from firsthand experience that even twisted, sheilded pairs driven by differential transceivers are affected by impressed noise.

    Have you ever seen an RC plane take a 'radio hit' from some else's transmitter? Same deal with PED's; you'll never know what frequencies are being emitted, so why take chances?

  • Back in the mid to late 1980s use of ham radio and CB transmitters aboard airliners was specifically prohibited by the FCC/FAA (they did this jointly). If memory serves correctly, they had found that transmitters could cause the hatches on doors to unlock and other things that would result cabin depresurization. NOT a good thing at all. :)

    1. I work for an airline. I do not speak for them.
    2. My airline does allow cell phone use on the aircraft as long as the main door is open. When the door is close an announcement is made to discontinue cell phone use.
    3. It is a well established here that ground crew who use their two-way radios inside the cargo compartment often trigger the fire detectors. Say what you want about "That shouldn't happen," but it does. If the same thing happens in the air; first, the crew dumps halon into the cargo hold (fluffy the cat dies, too) and they land immediately. If the investigation shows a passenger cell phone caused it. That passenger will be fined lots of money.
    4. Aircraft use a landing signal system called ILS or "Glide Slope" to guide the aircraft to the end of the runway. There are big radio transmitters at each end of the runway which emit multiple finely tuned radio signals that form an interference pattern that the onboard aircraft use to determine if it is properly aligned in the runway. This is a "Good Thing." It is very good if the pilot can't see the runway. Stray radio signals from almost anything can mess up the the interference pattern. This is why you are required to switch off your laptops, palm pilots, walkmans, etc ... During takeoff and landing. In case you were wondering why takeoffs too, is because every takeoff procedure assumes that there might be an immediate emergency landing.
    5. Inside a every US flaged airplane and US airport, the FAA is god. FAA regulations are gospel. (Except for the US Secret Service, but that's another matter isn't it) If the FAA has a rule regarding radio gear, any FCC ruling doesn't mean jack. Many aviation agencies of other countries are set up the same way.
  • The point is not that RF use = instant bad air day, but that RF use - whether it be cell phones or even a regular FM receiver - changes the odds. 99.9% of the time nothing happens. (This is why you're not going to use this as a terrorist weapon.) But sooner or later, a pilot doesn't pay as much attention as he should to a warning light because of false alarms, or somebody mishears a air traffic control alitude correction and you have 300 dead people.

    Most safety regulations are built around a cold look at long term odds. For example, (pulling figures out of nowhere) imagine cars with no air bags - 100 people die in auto accidents a year. Then air bags are put in. Now only 40 people die, but 10 of which were somehow the result of being hit with an airbag. It's still better for everyone to use airbags, even though they killed 10 people.

    In the long run, it's better for you to reduce the amount of RF crap you're putting out, period.

  • It involved a passenger listening to an FM radio while a plane was on an instrument approach in the 1950s. The local oscillator leakage caused a false indication on one of the ILS (Instrument Landing System) instruments (I think it was called the localizer). The VHF aeronatutical band is just below the commercial FM band, by the way.

    Anyway, the plane crashed, the NTSB figured it out, and then made the rule about electronic devices.

    Fortunately, all commercial jetliners now use inertial navigation systems, so this particular failure mode is much less likely. A terrorist would not be able to crash a plane in this way. ILS systems are still in use, however -- and nobody wants to find out about another electromagnetic compatibility problem via an accident investigation.
  • If you're a computer user, and most especially if you're a computer programmer, then you have good reason to read The Forum On Risks to the Public in Computers and Related Systems, available as comp.risks [comp.risks] on the Usenet News, and on the web at http://catless.ncl.ac.uk/Risks/ [ncl.ac.uk]

    Cell phone interference to airliners has been discussed there extensively.

    For those of you who work where they're considering replacing a real OS installation with Windows NT [geometricvisions.com], consider this post I contributed:

    USS Yorktown dead in water after divide by zero [ncl.ac.uk]

    The Yorktown has to be towed back into port after a sailor entered "0" into a data entry field and it crashed the ship's entire NT network.

    Mike

    Tilting at Windmills for a Better Tomorrow

  • Let's get this straight, folks. Photons from cell phones (or power lines as well, for that matter) do not have even a fraction of the energy needed to generate free radicals such as singlet oxygen (responsible for most carcinogenic genetic damage), let alone to break peptide bonds directly. In short, cell phones are incapable of damaging DNA or creating chemicals which can damage DNA. They might cook your flesh if operating at sufficiently high power levels (which they don't), but they won't cause cancer. For that, you need ionizing radiation (UV and up...). Saying that cell phones can cause cancer is like saying that the wake from a surfboard can capsize a supertanker.

    If you are really worried about cancer, stay out of the sun, watch what you eat, and don't smoke. And try not to worry about the fact that there will still be a one-in-a-bazillion chance that one of the numerous stray cosmic ray gamma photons constantly bombarding your body will happen to nail the telemerase inhibitor in one of your cells and turn it cancerous...

  • I want to know how the electronics on a plane can get affected by the output of a cell phone, and not get totally roasted by flying through a lightning storm!

  • Nope, it was a brand new 767. There's an excellent story about it here [frontier.net]. Also, the pilot was commended, not fired. He flew gliders in his spare time, and had the expertise to bring the jet down when there wasn't even an official procedure on dealing with a failure of both engines.

    From that page:

    The flight crew had never been trained how to perform the drip calculations. To be safe they re-ran the numbers three times to be absolutely, positively sure the refuelers hadn't made any mistakes--each time using 1.77 pounds/liter as the specific gravity factor. This factor was written on the refueler's slip and was used on all of the other planes in Air Canada's fleet. The factor the refuelers and the crew should have used on the brand new, all-metric 767 was .8 kg/liter of kerosene.

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