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The Real Reasons Phones Are Kept Off Planes 642

Posted by CmdrTaco
from the flip-the-switch dept.
jcatcw writes "Mike Elgan argues that the the real reason that cell phones calls are not allowed is fear of crowd control problems if calls are allowed during flight. Also, the airlines like keeping passengers ignorant about ground conditions. The two public reasons, interference with other systems, could easily be tested, but neither the FAA nor the FCC manage to do such testing."
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The Real Reasons Phones Are Kept Off Planes

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  • Vapidity all round (Score:0, Interesting)

    by Anonymous Coward on Sunday April 08, 2007 @11:59AM (#18655503)
    First things first: the less annoying single page print-version of the article:
    http://www.computerworld.com/action/article.do?com mand=printArticleBasic&articleId=9015839 [computerworld.com]

    Now, from FTA:

    The airlines also benefit in general from passengers remaining ignorant about what's happening on the ground during flights, including personal problems, terrorist attacks, plane crashes and other information that might upset passengers.

    Yes, PH3AR teh information! Teh interweb must also be teh BANNED!!! What would happen if we let people view things like THIS [digg.com] on their cellphones?

    But the "What's wrong with the ban?" section is lame too:

    What's to stop terrorists from testing various gadgets, finding the ones with the highest levels of interferences, then turning on dozens of them at some crucial phase of flight, such as during a landing in bad weather?

    If we use cellphones, then TEH TERRORISTS HAVE WON!!!!11!!eleven!!

    At least we still have Mocha [digg.com] :-)
  • by DarkFencer (260473) on Sunday April 08, 2007 @12:01PM (#18655523)
    There are already enough planes that have satellite television (including news channels) along with air phones (at a very high cost - yes but still a source of information.

    The real reason? Its bad enough when people are yapping on their phones constantly on the ground. Getting stuck on a plane near someone who won't shut up on the phone is MUCH MUCH worse due to the duration and the captive audience. For that reason I hope cell phones are never allowed (and if they are it should be a cell phone only section kept reasonable sound proof from the rest of the plane).
  • by symonty (233005) on Sunday April 08, 2007 @12:15PM (#18655647) Homepage
    With no players anymore in the US, Verizon out and aircell now offering Wifi instead of phone calls, this is not a reason.

    Also the only phones still avaliable on planes are run by ARINC and SITA, which both now have a picocell replacements under testing for installation this year.

    There is no technical nor marketing reason you can't have a cell phone on board, if cell phones were a real danger then they would not be in carry on allowance anymore.

    FAA is very conservative, and the FCC is a political body.

    That is all
  • GSM network (Score:2, Interesting)

    by blwrd (455512) on Sunday April 08, 2007 @12:22PM (#18655707)
    At least based on this site [moo.pl], there is absolutely no GSM reception above 650m (2100ft). So I guess the plane would need an own GSM base station for the cell phones to work.
  • by Anonymous Coward on Sunday April 08, 2007 @12:26PM (#18655749)
    Hearing one side of conversation is far more distracting than hearing both sides. You can't shut your ears like you can shut your eyes - you can TRY to ignore sounds, that's about it, and your brain unavoidably tries to use a significant amount of processing power trying to reconstruct the other side of one side of a conversation. This is not deliberate, it just happens, even if you *really* don't *want* to listen in. Plus, people on the phone consciously or unconsciously talk more loudly and more clearly than in normal conversation. That is really annoying, because it makes it harder to ignore them.

  • by Jeff DeMaagd (2015) on Sunday April 08, 2007 @12:29PM (#18655779) Homepage Journal
    Reception is very weak at best in mid-flight anyway. The only decent way to prevent people from using the phone on ascent or descent is to take them away, or better, turn the passenger cabin into a faraday cage.

    I think it was Jet Blue that had the situation where passengers could see the news about their flight through satellite TV, something about damaged landing gear. I don't remember anything about a crew or passenger mutiny in the news reports.
  • by LighterShadeOfBlack (1011407) on Sunday April 08, 2007 @12:30PM (#18655799) Homepage
    Chuck them overboard?! Could we make them walk the plank aswell?

    Seriously, if that was really the reason then you'd have to ask why planes have reclining seats and music via headphones. Each of those is equally capable of being annoying.

    TFA's "they don't want testing because testing costs money" argument doesn't stand up to scrutiny either. Just because planes could be allowed to tested for phone usage doesn't mean planes would have to allow phones to be used. It would be up to the plane manufacturers to decide to have their plane designed and tested for that "feature" and then up to the airlines if they wanted to pay the inevitable extra cost for such a plane, and then of course pass that on in extra cost to the passengers.
  • by dheera (1003686) on Sunday April 08, 2007 @12:34PM (#18655839) Homepage
    I'm fine with babies screaming and people having conversations. I don't mind if cellphones can be feasibly allowed and people be required to keep their conversations to a whisper.

    What *does* bug me the most about travelling on planes:
    1. Fat people. No offense, but I feel like I have a right to my entire seat and 50% of the armrest. I don't mean to offend obese people, but if they cannot respect my rights to that space without elbows and legs brushing against me for the entire flight, they need to purchase a first class seat or two seats or something. No, it's *not* ok to plop yourself down and arrogantly and comfortably take up the entire both armrests on both sides of you. If you are fat, it's your fault. Period.

    2. Smelly people.

    3. People who aren't nice about travel needs (like having to get up to go to the bathroom, get up to walk around because you have a medical condition that requires you to), people who argue with flight attendants about stupid stuff ("No! I paid for this seat and I'm *not* moving" [even though an old woman really needs that seat])

    4. People who aren't nice to you. I was once on a flight and after the lights were turned off in cruising altitude, I slowly put my seat back to go to sleep. A couple of minutes later, the guy behind me started pounding on the seat, probably trying to tell me to put my seat back in the upright position. He didn't bother to talk at all, didn't bother to get up and at least signal at me nicely if he didn't speak English, he didn't do anything. He just kept pounding on my seat for the entire flight, periodically.

    5. People who rest their hands on the top of the seat in front of them, in a fashion that causes their fingers to touch the person's hair in front, and refuse to remove their hand.

    6. People who look so antisocial and angry-faced and silent that you can't figure out if they have some terrorist plot behind their eyes. Cheerful people are much easier to be around.

    7. People who think that a flight is the place to hit on girls.
  • Re:Rubbish (Score:3, Interesting)

    by Blahbooboo3 (874492) on Sunday April 08, 2007 @12:35PM (#18655851)

    If you are commenting about the fear of conflicts due to rude behavior, the AirFones are fine because no one uses them. I may have seen this phone used 1-2 times in the last 10 years. The fact is they are HUGELY expensive so people either don't use the service or use it for 2-3 minutes at most.

    Now, compare that with a plane full of people with cell phones that have cheap plans where they can gab on for hours and, with power adapters, the phone can last the entire flight. Awful right? Even the nicest person would be hard-pressed to not start telling the person to hang the damn thing up.

    I already see this on Amtrak between Boston and NYC. People gab loudly and for HOURS. Amtrak had to make a QUIET CAR because the amount of noise had gotten so awful due to impolite cell users.

  • by nhtshot (198470) on Sunday April 08, 2007 @12:36PM (#18655861)
    I posted this to the original article as well, but I felt the slashdot community might derive some value from it as well. The interference issue is a VERY real one. I can't emphasize this enough. It's easy to debate this issue on the ground, but try debating it 2 miles above the ground when your only lifeline is a thin needle on a panel that is controlled by a radio transmitter on the ground. I have a personal experience with cellphone nav interaction. I've also watched the mythbusters episode. Everyone here knows that mythbusters, while entertaining, is not entirely scientific. I certainly am not willing to stake my life on the thoroughness of their conclusions.

    Without further prefacing, here is my original post:

    You mention in your article that "Many headsets used by private pilots come with jacks for using them with cell phones. The manufacturers say they're for use on the ground only. But many private pilots use them in the air without incident."

    I fall into this category. However, I've also seen the dangers of airborne cell phone use. I carry a Nextel branded Blackberry. From my experience, it's not a very good phone to use on board an aircraft. About every 20 minutes or so, the phone goes into a signal frenzy. It's as if it finds multiple strong towers to connect to and is unable to choose. This results in a barrage of beeps and lights while it tries to figure out what's going on.

    Furthermore, the risks of interference are very real. When I'm using the phone, I never notice the interference. I recently let someone else use my phone and was very surprised. My headset (flight radio headset) emitted a horrible scratching noise. I was totally unable to hear anything on the radio. I quickly looked at my VOR (radio navigation, NOT a gps) , and noticed that it was off coarse as well. Now, had I not been certain that I was on the right course, I might have well thought I was off course and corrected in an ultimately wrong direction.

    I'm not sure if you're familiar with VOR technology, but it's the primary aviation navigational aid. GPS is wonderful, but it's still not the primary navigation mechanism. GPS is considered a "non-precision" navigation tool. VOR and ILS are still the primary mechanisms and they are dependent upon terrestrial radio transmissions. This is where the cellphone interference comes into play. Most cell phones operate in the 800mhz range. I'll save you a lesson in radio technology by simply stating that they can often have harmonic emissions in the same bands as used for aircraft navigation.

    While you state that countless numbers of phones are left on during flights, this is not particularly dangerous. A phone ranging a tower is only actively transmitting for a very short period of time every 20 minutes or so at regular speeds. A phone that is in active use is a source of radio emissions that is in VERY close proximity to the aircraft communications and navigation antennas and is operating on a frequency that can have interfering harmonics. I have personal experience with the reactions a nav needle can have to a cellphone.

    Imagine if the weather was bad (instrument meteorological conditions or IMC) and you were trying to land a large passenger airliner using nothing but a small needle on the panel to align with the runway. Then, a passenger starts talking to their uncle Bill about his bypass surgery and that needle jumps even 10 degrees off position. Now, instead of aligning with a runway, you're aligning with a corn field.

    To answer your thoughts about shielding, that's not a viable solution. You would either have to shield the passenger cabin from radio emissions or shield the comm/nav antennas from it. In either case, the shielding to protect them from each other would seriously impair their usefulness. A passenger cabin shielded from RF emissions wouldn't allow your cell signal to get out, thereby negating the purpose. Shielding the comm/nav antennas sounds like a good idea until you realize that oftentimes nav aids and aircraft controllers a
  • by koreth (409849) * on Sunday April 08, 2007 @12:40PM (#18655891)
    Plus, Europe doesn't have a bunch of competing cell phone standards to deal with. It's much easier to equip planes with cell-tower equivalents when you only have to do GSM. An American carrier that wanted to provide all its customers with cell service would have to support a couple of extra signal types, presumably making it more expensive.
  • Not quite (Score:5, Interesting)

    by WindBourne (631190) on Sunday April 08, 2007 @12:40PM (#18655895) Journal
    My father is a retired Pilot (Air Force, then the American Airlines). Since I used to work for Jeppesen, we have had some interesting conversations about this. He has said that he has seen nav equipment messed with that the FAA said was cell phones. Now it was early 90's, and likely to be one of the analog phone, but they were not certain. But some of his old co-pilots (now all senior captains for American), says that several instruments will be interfered with from time to time and they believe it to be cell phone. In general, they claim that most of the interference occurs on the ground (i.e. as soon as the phones are turned on). Now, I do not know why that is, but I would want to make certain before allowing them to be used. It is possible that it is just one frequency or type of phone that is causing the issue. My question is, why has the FAA not determined where the issue is? ALPA is actively pushing against allowing the phone usage until FAA or FCC can explain what is causing this.
  • by GroundBounce (20126) on Sunday April 08, 2007 @12:41PM (#18655905)
    I believe this hits the real point. I travel a fair amount on business and spend enough time in airports to know that there are a significant number of people who would probably talk on their phones as continuously in flight as they do on the ground if given the chance, and these aren't just businesspeople. Either way you handle this in flight will be a problem. If cells can be used anywhere on the plane, there will be a big backlash of annoyed passengers; if they are confined to a few rows, they will annoy and interfere with each other which will encourage many of them to ignore the row designations and still cause problems for others; plus even if they don't, it will still be a problem for several "normal" rows adjacent to the cell phone section.

    Wifi on planes will be MUCH less of a problem in terms of annoyance to other passengers.

    Unfortunately, the best solution is the one that is already in place on some planes - a public pay phone in the seat. It costs money to use, so people won't use it idly, but important business and personal calls that justify the cost can still be made.

  • by freeweed (309734) on Sunday April 08, 2007 @01:31PM (#18656245)
    I just flew on a bunch of different planes in the past week, and a couple of them had the control tower chatter actually broadcast on one of the channels of the in-flight entertainment system.

    It was actually pretty cool to hear the various airplanes yak with the tower. O'hare is a busy airport (to say the least), and it was astounding to listen to them juggle all the incoming planes. What was particularly funny was listening to them berate our pilot - the guy mumbled a bit, so the flight number kept getting cut off. The tower had to repeatedly ask him to repeat, and eventually they started making fun of him. Things like "well, this particular pilot doesn't feel he's important enough to respond to us". Tres droll.

    Also cool was listening to the tower give directions (turn left, etc) and feel the plane immediately respond. All in all, it sounded pretty much exactly like it does on TV/movies. I'm sure if there were any actual flight emergencies, it would have been broadcast for the passengers to hear - unless there's some protocol to shut that channel down when things go amiss - which would just alert passengers to a problem anyway.
  • by Dun Malg (230075) on Sunday April 08, 2007 @01:33PM (#18656259) Homepage

    People tend to talk louder on cell phones than regular phones. [npr.org] There is no feedback of their own voice.
    Indeed. On regular landlines it's called "sidetone". It's an artifact of the single shared copper loop heritage of the POTS system that dates back to the 1870's. Cell phones lack sidetone because they use two separate circuits for transmit and receive. The problem arises from people not being self-aware enough to realize that the lack of sidetone is causing them to unconsciously raise their voices. I strongly urge all people to be mindful of their voice volume on cell phones. Seriously, consciously will yourself to use a low conversational volume level. You might be surprised to find people can understand you better.
  • IEEE Spectrum had an article about this last year ( http://www.spectrum.ieee.org/mar06/3069 [ieee.org] ); the authors actually sampled in-flight RF data and reviewed some related publications. They also discussed the current reporting methods for HED interference and discussed some of the reports. Bottom line for those that don't want to read the whole article: some cell phones and other devices emit innocuous signals that pose no significant danger, while _other_ cell phones and devices pose significant risks of interfering with avionic electronics, depending on the frequencies they use. This inconsistency alone is a problem. "Sure, you can use your AT&T phone, ma'am. I'm sorry sir, you have to turn your Sprint phone off or we're all going to die". The FCC and FAA do not work with each other (as a rule of thumb), so both the technical and regulatory issues can conflict with one another.

    It's a good article for the layperson, I'd encourage reading it.
  • by tcgroat (666085) on Sunday April 08, 2007 @01:45PM (#18656361)

    TFA says:

    Also: If real testing were done, and the nature of the problem fully understood, it would become obvious that airplanes could be designed or retrofitted with shielding and communications systems that would enable safe calling through all phases of flight. But that would cost money.

    Real testing has been done. Unintended emissions from the phone have been identified as the culprit, not a deficiency in the navigation equipment. The aircraft's receivers are doing exactly what they are supposed to, responding to signals of certain frequencies arriving at the antenna. Once the phone pollutes the spectrum with spurious signals, nothing can protect the receiver. The shielding and filtering must be applied at the problem, which is the phone. Since the competitive consumer phone market demands the lowest possible cost, once a phone meets the minimum legal requirements they won't add another dime of product cost for further interference control.

    Intereference does not occur every time, but when it does occur there has been a demonstrable cause and effect relationship. Start with this NASA case study [nasa.gov](long pdf warning).

    In July 2003, it was reported to the Federal Aviation Administration (FAA) that a cellular phone when turned on simultaneously interfered with three different aircraft GPS receivers, causing complete signal loss. The three GPS receivers were using three separate antennas, and were installed on a small aircraft. The phone was on, however, calls were not made during the incidents and subsequent tests. [emphasis added]

    In an email message to the FAA, the company who owned the airplane reported the subsequent tests taken to prove a clear and convincing direct relationship between the phone being in ON-mode, and interference with the three onboard GPS systems. The company verified several times, in multiple flights over different days, that the interference problem could be recreated reliably in the air by having the phone turned on. The interference disappeared when the phone was turned off or covered behind a metal object, and re-appeared when turned on or brought into the open again. In addition, the company conducted tests at two different places to ensure that it was not dependent on location, and were able to reproduce the interference effects at both. The interference occurred when the plane was in the air, but not on the ground. Tests using other phones did not create interference problems on the same aircraft and systems.

    Then consider this article from Spectrum [ieee.org]. On page 3:

    Our data and the NASA studies suggest to us that there is a clear and present danger: cellphones can render GPS instrument useless for landings. Clearly, the cause of the problem is that the FCC issues RF emission standards for consumer electronics, conferring only minimally with the FAA and with no formal consideration of the implications of those standards for the aircraft environment. For its part, the FAA relies on the airlines to initiate safety plans and, like other government agencies, defers to the FCC on questions of electromagnetic radiation.

    And from page 4:

    All in all, we found 125 entries in the ASRS [Aviation Safety Reporting System] database that reported PED interference. Of these, 77 were considered highly correlated, based on the description of observed PED use and interference occurrence.[emphasis added] The reports included cases of critical aircraft systems such as navigation and throttle settings being affected. Based on the random sample entries from 1995 to 2001, we estimate that the average number of reported interference events might be as high as 23 per year.

    It's no conspiracy, and no urban lege

  • What I want... (Score:4, Interesting)

    by The Living Fractal (162153) <`banantarr' `at' `hotmail.com'> on Sunday April 08, 2007 @01:46PM (#18656365) Homepage
    So this is like.. tangentially OT.

    But, how much money could I make if I started a business that installed Faraday cages into movie theaters? Could I completely block all cell traffic with one? And could I install the cages relatively cheap and keep them invisible? See, I know there's been talk amongst movie theaters of using jammers to stop cell phone use. But the FCC is against that and it doesn't look like it's going to happen. But can the FCC stop me from constructing a faraday cage around my theater to 'ensure the highest degree of fidelity of the digital projection equipment, thereby ensuring the best viewing experience'?

    I'll tell you what, if I know one theater in town has faraday cages and the others don't.. I'm goin to the one with the cages.

    A lot of people argue that they need their cell phones during a movie in case of emergency situations. I think that's bullshit. For decades people managed to go to movie theaters without cell phones. They accepted there might be emergencies happening that they weren't aware of until after they left the theater. They accepted this because whenever an emergency happens and you are twenty minutes from the scene you are 99% of the time too late anyway.

    Someone enlighten me here, what kind of emergency can you really expect to respond to fast enough to make a difference by racing out of a theater to the scene of the emergency? By the time you get there either the emergency is over or people who are supposed to handle that sort of thing (you know, EMT, Firefighters, professionals...) have already done so. But please, give me an example of how I could be wrong. I'm curious. There has to be something.

    TLF
  • Re:funny (Score:5, Interesting)

    by w9wi (162482) on Sunday April 08, 2007 @02:14PM (#18656579)
    Yep. The coverage of even a small, low-powered VHF radio increases dramatically when operated from an aircraft.

    In the U.S., Class A FM broadcasting stations are limited to a power of 6,000 watts at a maximum antenna height of 100m. Higher antennas are allowed if the power is reduced to compensate. [fcc.gov]At an antenna elevation of 600m, power must be reduced to only 150 watts (?!) to achieve the same distance coverage. Translate those figures to a cell phone with a rated power of no more than 3 watts, and you're talking about limiting power to 0.08 watt at 600m.

    Of course, commercial aircraft fly a LOT higher than 600m!

    The cellular network has far more subscribers than it has channels. To work, it depends on the ability to reuse a channel throughout the service area. If I place a phone call from my home 40km northwest of Nashville, the same channel can be reused in downtown Nashville, and on the city's west side, and in Donelson, and Brentwood, and Smyrna, etc., etc... My phone, about 1.2m off the ground, has a range of only about 6km.

    If I place that call from an airplane flying 8,000m above my home, every base station in the greater Nashville area can receive my signals. Now, "my" channel cannot be reused at all.

    If it were just me, that wouldn't be a problem. If it were, say, 10% of the passengers on each flight - well, I don't think it's hard to see how that could use up all available channels in a hurry. New channels aren't cheap. Nextel is paying to replace [2ghzrelocation.com]almost *all* the microwave remote broadcast equipment in use by U.S. TV stations, so they can free up some remote broadcast spectrum for use as cellular-telephone channels.

    Here's an idea: allow calls from aircraft, but allow cellular providers to charge enough extra for airborne calls to cover their costs in adding more channels. I'll bet after the next billing cycle, the number of calls made from aircraft would plummet!
  • by maxwells_deamon (221474) on Sunday April 08, 2007 @02:19PM (#18656611) Homepage
    Many large cities have these things called mountians and tall buildings in the middle.

    If this was a serious problem they would at least have signs telling us not to use our cell phones in high places. Even if they could not enforce it it would help.

  • by that this is not und (1026860) on Sunday April 08, 2007 @02:48PM (#18656865)

    It's not technical but social. If that loud mouth jerk salesman doesn't shut up at 30,000 feet I will shove that phone so far up is arse that the vibrated mode will help break down his food.


    That is the way I interpreted the fear of crowd control problems if calls are allowed during flight. cited in the summary. I assumed it was the fear of controlling the crowd of fellow passengers from bludgeoning blabbermouth fellow passengers to death.

    Until there is a mechanism on each plane to jettison the bodies of cellphone users who have been thrashed to death by fellow passengers, I don't think the planes are ready. I can't see passengers having to endure long 9-12 hour flights with the bloody mess. And I certainly don't want to discourage anybody, anywhere, from smacking the viscera out of public cellphone blabbermouths.

  • by Chris Carollo (251937) on Sunday April 08, 2007 @02:56PM (#18656923)
    I fully believe that cell-phones can interfere with aircraft nav systems (the fact that they interfere with PC speakers and conference-call microphones is plenty of evidence for me).

    However, there's also a restriction on hand-held TVs/radios and GPSs, and I've always wondered why, since they're all receive-only. I don't see how it's possible for them to cause any interference (or at least no more interference than a laptop computer) since they're only picking up on signals that are already passing through the plane from an external source.

    So, does anyone have any info on why those are banned as well?
  • I doubt it (Score:4, Interesting)

    by einhverfr (238914) <chris...travers@@@gmail...com> on Sunday April 08, 2007 @03:08PM (#18656987) Homepage Journal
    Jet Blue offered live on-plane television programming, which allowed the passengers of the plane with the stuck landing gear to watch the news coverage of their problem live while on the plane.

    United often allows you to hear the flight deck communications.

    Some airplanes still have in-plane phones using something similar to a cell network (with much bigger cells). So not all phones are banned.

    If this was the real problem, these things would also have been banned, or never allowed but they are not.

    The real reasons for banning phones are:

    1) Paranoia by the FAA about malfunctioning devices (which is valid, BTW-- it doesn't usually cause a problem but I have seen radio intererence from many other devices that you wouldn't expect).

    2) Concern by the FCC about the effect on ground-based cell systems. I.e. if you use your cell on a flight high above New York, how many cells are you reserving bandwidth on?

    This article was largely typicall Slashdot incite....
  • by TermV (49182) on Sunday April 08, 2007 @03:41PM (#18657209)
    If cell phones and two-way pagers indeed had the ability to interfere with aircraft to a point where it compromises safety then the TSA should be confiscating them rather than bottled water and toothpaste. At least it's a more plausible threat than "liquid explosives". Perhaps the fact they are *not* confiscating them is telling.

    Actually I'd like to see that. Confiscating a bunch of inexpensive water bottles in the name of security is a relatively benign way of maintaining the appearance of security. Being willing to risk massive public fallout by confiscating expensive cell phones would show they are actually serious.
  • by FlamingLaird (245347) on Sunday April 08, 2007 @03:50PM (#18657249)
    I can verify from personal experience that MY cell phone does cause interference with radios. I'm a Private Pilot and I have a two year old Sony Ericsson. If I forget to turn the phone off, I can hear a cycling beep sound in my headset every time the phone is transmitting (i.e. ranging to a new cell tower or checking my email etc.) The VHF set also shows that it's receiving, so its actually picking something up through the antenna.

    It's not particularly loud, and I haven't had any trouble hearing ATC over it. On a commercial jet... with several hundred cell phones, and the much higher importance of ATC calls under IFR... I can see where it could be a major problem.

    Are there ways to solve the problem? Sure. Is it really worth spending the resources to test and resolve in light of the social factors? I'd say no. I personally consider time spent on commercial flights as downtime. I don't want people to be able to get ahold of me, I want to read a book or watch a good movie.

    If you really are important enough you HAVE to be in communication 24/7... well buy your own jet =)
  • Re:funny (Score:5, Interesting)

    by runexe (24089) on Sunday April 08, 2007 @04:01PM (#18657327)
    Cell phones do interfere with other devices - that the nature of all electronics - especially ones in which radio transmitters play a leading role. There is no getting around the fact that cell phones create radio 'noise'. Yes, they have been tested to make sure they are only creating radio emissions to some agreed upon level in the band/frequencies they are licensed to transmit on, and some (lower) agreed upon level outside of that band. However, certifying electronics for use on-board planes is a little more of a dicy issues - because the mere possibility that booting up your laptop during landing might generate enough noise to screw with the GPS, or the ILS systems that are helping the pilot guide the giant metal tube full of jet fuel and fragile humans to a concrate surface is a scary enough scenario that the FAA has decided its easier to just have a blanket ban on such things during take-off/landing. The ban on cell phones is a similar conservative (or paranoid if you prefer) move: its easier to say its not allowed than to test its enough to be reasonably certain its safe. In reality modern digital cell phones inside a modern jet could be perfectly safe - but there are a large number of models of airframes out there, and a much much larger number of cell phone models - many of which can operate in several different modes and corresponding frequencies. Certainly I'd prefer they spend the time to check it out some more so that in the future they can certify my cell phone is safe to use on the particular plane I'm stepping onto so I can talk during particularly long flights. In the meantime I have to wait until the plane taxis to a full stop by the gate before powering it up and making the call to say we've landed. An inconvenience, but I don't mind the fact that they're focusing more energy on the making the plane safe part and haven't devoting their full energy to making it easier to make phone calls during the flight part.
  • Calling bullshit... (Score:4, Interesting)

    by Ididerus (898803) on Sunday April 08, 2007 @05:36PM (#18657887) Homepage
    I can tell you the TRUE reason cell phones are not allowed on airplanes.

    I fly on Air Force flights, which are not subject to FAA regulations, and the main problem with cell phones on airplanes is the fact that they DO NOT WORK. The transmitter in your phone is not powerful enough to reach more than say, 1000m. Your phone will go dead at less than 10,000 ft of elevation. Add this to the fact that cell towers are not powerful enough to reach the average cruising altitude of ~30,000 ft.

    Fear of instrument interference was due to older, analog units with less defined spectrum. With ALL equipment in aircraft being shielded these days there is almost NO possibility of a disturbance in flight.

    Besides, your 50mW transmitter is no match for, oh, the sun. And all the other background noise that is present in our atmosphere these days. I would bet that the electric motors on the landing gear ( or hydraulic pumps that may power them) put out more EMF in just about every frequency known to man than all the cell phones that might be in call at once.
  • by cmd (56100) on Sunday April 08, 2007 @05:45PM (#18657933)

    I need to point out that VOR navigation has gone the way of the DoDo bird. I cannot imagine anyone in a modern aircraft spending the time to fiddle around with triangulating VOR's when the GPS is sitting there telling the pilot the current position within 10 meters, current groundspeed, and the exact distance to any point on the planet (within 10 meters). The nav radios are now used as a backup to the GPS, if at all. (Autopilots rely solely on GPS.)

    I suppose one could make an argument that VOR's are useful in case the GPS fails, but I would retort that one would be much better off with a second redundant GPS on a separate power supply. Which system sounds more reliable: one based on a collection of a couple dozen satellites with no moving parts located *above* the aircraft where there is no weather or terrain and cannot be vandalized, or a system based on hundreds of rotating VHS radios scattered around on the ground, subject to weather, terrain, vandalism, and maintenance problems? Also, it is a simple and prudent matter to mount the GPS receiving antenna so that it is looking up and shielded from RF radiated from below. (A secondary receiver can be located below for extended inverted flight, if that is a concern.) GPS is in all ways better than VOR.

    Secondly, the whole interference argument is moot. It doesn't matter. Out of the 137 passengers on a 737, how many of them have mobile phones? I'll guess 30%, or 41. How many of them actually turn their phones OFF when told to do so? I'll guess 50%, leaving 20 phones actively seeking cell towers for the duration of the flight. As far as interference goes, there is really very little difference between a handset trying to negotiate with a tower and one that is locked on and transmitting data. In fact, the device typically radiates more power when negotiating. The only way to prevent this situation is to be absolutely positive all the devices are OFF (including the ones in the baggage hold) -- an impossible task, or move the devices out of range of the towers (five miles UP) -- an inevitable task. So the solution is either impossible or inevitable, neither requiring any action on anyone's part.

    Furthermore, radio communication is most critical during takeoff and approach. This is precisely when the devices onboard are the most active -- low altitude over populated areas, within range and transitioning cell tower coverage at a rapid clip. And guess what? Not a single significant incident reported. There have been anecdotal reports, but nothing more than mild curiosities.

    This whole argument is a bunch of hooey. The airlines just want to figure out a way to monetize the connections, others want people to just shut the hell up and let them sleep, and the FAA is (as usual) in a state of paralysis. (This is usually a good thing.) The only thing I am pretty sure about is that it has nothing to do with radio interference.

    However, if passengers did want, and were allowed, to use mobile phones openly (as opposed to furtively ;) ) in flight it would require a system to relay the signals to the network in a way that overcomes the problems of distance and speed. This will most likely (must be?) a small cell tower (picocell) located on the plane that relays the signals to a satellite link, then down to a central terrestrial hub. Once all the onboard devices discover the very nearby cell tower, they all back off to their lowest power settings and contently sit in low-power mode for the duration of the flight. Even if the picocell were not relaying the signals I think it is the only viable method to control the user devices. But this is a few hundred thousand dollars per aircraft to install, ongoing maintenance costs, and additional regulations and contracts. Not to mention media headaches when some tech blog points out that the airline is now bathing the passenger cabin with microwave RF. So it does not surprise me that this is happening slowly, but I am confident that within the next five

  • by RubberDogBone (851604) * on Sunday April 08, 2007 @06:34PM (#18658233)
    If cellphones were really really dangerous, we'd have aircraft graveyards everywhere, especially around airports.

    What do cellphones talk to? Cell towers. Where are those towers? EVERYWHERE, and they all operate at much higher power levels than any handset.

    If there was some sort of danger, cell tower signals from the ground -particularly towers near airports where they are always A LOT of such towers- would be knocking planes out of the sky on an hourly basis from miles away. Every airliner in the sky flies over hundreds of these towers on every flight. It would be like the worst anti-aircraft fire ever devised.

    But it doesn't happen.

    And cell towers are hardly the most powerful transmitters in the wild. A cell tower throws out a couple watts. A TV transmitter can throw out a million watts and there are thousands of those towers too.

    Aircraft operate happily amid a sea of RF and generally nothing goes wrong. So the idea that a wimpy little cell handset are threats are just overblown assumptions, unproven and unrealistic.
  • by Peter Simpson (112887) on Sunday April 08, 2007 @06:38PM (#18658259)
    It's generated in the part of the phone called the "network", which, among other things, contains something called a "hybrid coil", which allows the single pair of copper wires to separate the outgoing and incoming voices. In addition to that function, there's also a "sidetone coil" that couples a sample of the outgoing voice into the receiver circuit.

    In electronic phones, it's done slightly differently, but there is absolutely no reason it can't be done in cell phones, and it often is.

    The explanation is correct in one respect, though. Increasing the sidetone will cause the talker to lower their voice.

    Used to take phones apart for fun, have designed hybrid circuits.

  • by SnowZero (92219) on Sunday April 08, 2007 @06:50PM (#18658323)
    I don't think "It was the airplane's problem for having faulty shielding, not the electronic device" would be much of a comfort to relatives. Can't we just be a little patient while the last of the analog phones (which really can interfere) disappear, and the FAA/FCC test out onboard picocells? People here talk like addicts -- as though somehow its impossible to not use your phone for a few hours.
  • Cell tower troubles (Score:3, Interesting)

    by SoopahMan (706062) on Sunday April 08, 2007 @06:52PM (#18658345)
    This is more or less the case. I was watching CSpan as a bill considering the use of laptops which connect over the cell network on airplanes was debated, and the debate got straight to the point: We should allow laptops because they are not intrusive, but no one likes a cell phone call on an airplane so the nuisance should continue to be banned. At no point during the Senate debate did anyone show proof of serious harm to the airplane or cell network from cell phone use, and it's interesting that no one had any serious objections to laptops connecting wirelessly over that same network.

    Although the cell network concern is somewhat legitimate, the truth is it's a simple software problem of anticipating this kind of broad network access and handling it appropriately. It's not a serious technical challenge, it's just a limitation of SOME cell networks, for now. If the law changes, so will the software, so it can't be taken seriously.

    There is also some legitimate technical concern of radiation affecting internal plane signals. However, this kind of interference is only possible on unshielded cable on the plane, which presents a problem whether a cell phone is on or not.

    There are many reasons rumored (even by the FAA!) for the cell phone ban and the above are the only 2 with any technical basis, and even they just take a little more investigation to reveal their lack of merit. What was enjoyable was that the Senate debate didn't spend more than a few minutes pondering the technical concerns - they accepted them all as crap and moved directly to the nuisance issue, and focused primarily on that for the entire debate.
  • Re:funny (Score:1, Interesting)

    by Anonymous Coward on Sunday April 08, 2007 @09:16PM (#18659205)
    For one, I hate phones. Two, I hate people who spend their whole life on a phone. Three, flights are long and boring, perfect for a nice little nap.

    Mod this guy up.

    Seriously, folks, your life is not going to come to an end just because you can't jabber to your dullwitted "peeps" for an hour or two. You have no right to inflict said inane jabbering on those unfortunate enough to be stuck on the plane with you.

    Now if only they could enforce a requirement that the other passengers bathe, and require that infants and small children travel as checked baggage, like pets....

  • by NoMaster (142776) on Sunday April 08, 2007 @09:30PM (#18659285) Homepage Journal
    It IS an effect of the copper loop. Telephones contain a hybrid coil (hybrid network), the purpose of which is to separate / mix the sent & received audio. It's a clever application of balanced networks.

    Unfortunately, the copper loop is a complex impedance and varies with line construction. There are various balance network options (e.g. TN12, etc) which try to approximate a 'best match' to the line, but they're not perfect. The end result is imperfect isolation across the hybrid - i.e. some microphone sound appears in the earpiece.

    Oddly enough, it was found in the early days of telephony that this was in fact desirable; it made the phone sound more 'natural'. After all, when you speak normally some sound does reach your ears via the air - an effect which is reduced when you put a phone up to your ear. So, in fact, it's a happy accident that telephony hybrids are imperfect.

    Mobile phones don't have this effect (separate transmit/receive frequencies or timeslots), and the electronic hybrid in some wired phones is too good at matching the line, so some mic sound is deliberately mixed back in to the earpiece audio to create sidetone. AFAIK, the only reason why this is less effective in mobiles phones is purely a power issue - the mixed audio is reduced to an absolute bare minimum in order to shave a few microamps/milliamps off power consumption, and so extend battery life.

    (That's an overly simplified explanation - but, yes, I WAS a telephony engineer...)

  • by X-rated Ouroboros (526150) on Sunday April 08, 2007 @11:42PM (#18659915) Homepage

    Only if you've got a first generation analog brick-phone using FDMA. Since G2, the handset/cell interaction has been digital (The cell network was always digital) using TDMA or CDMA.

    TDMA on a moving target requires the handset ensure that the transmission occurs during its assigned timeslot. There is an acceptable amount of error built into the length of the guard interval between assigned timeslots. Violate the TMA assumptions of the code for calculating transmission timing significantly enough and the handset starts blabbing over into someone else's timeslot. Degradation of service occurs. This can be fixed by increasing the guard interval, but that reduces available bandwidth.

    CDMA was created with the shortcomings of TDMA in mind and does not suffer from them for the most part. The "soft-handoff" the CDMA performs as a handset moves from cell-to-cell could present a problem for the handset if it transverses through many cells rapidly and simultaneously. How the network deals with a rapid string of handoffs is entirely up to the carrier. One carrier flogged "no connection charge for dropped calls" back in the day, kept the code around, and ended up with malicious users being able to get unbilled calls by forcing handoff back and forth between cells before the tab started. The same thing happens unintentionally if you fly across a city and are legitimately changing cells fast enough. Who knows what other weird implementation specific things happen... The problem isn't with the technology, though.

  • by Anonymous Coward on Monday April 09, 2007 @01:02AM (#18660203)
    Great! so cell phones can disrupt airplane navigation systems? (presumably a cell phone in check-in luggage could do the same. Or an intentionally designed transmitter in luggage)
    Why the heck did my wife get her manicure set taken away before boarding the plane if the technology itself is susceptible to non-intentional interference. Bruce Schneier gets my vote for calling airline security since 9/11 what it is, "movie plot security".
  • by ysegalov (849765) on Monday April 09, 2007 @04:02AM (#18660735)
    You can redesign every plane, but still, it moves at 500mph, and the fading and Doppler effects will kill the cellular signal. Your handset is not capable of operating at these speeds.
  • Re:funny (Score:3, Interesting)

    by Falrick (528) on Monday April 09, 2007 @11:01AM (#18663127) Homepage
    Actually, you're wrong.

    Cell phones don't try to talk to as many towers as they can. They generally have a relatively short list of towers that they are interested in at a time (active set). They may scan as many towers as they can hear at once, but then they'll only keep track of perhaps the top 3. Even then, they aren't in constant communication with them. Cell scanning doesn't require any involvement on the part of the tower itself. The tower will be generating a pilot signal. The pilot is sent at a known power level and uniquely identifies each cell tower. The phone will be scanning for these pilot signals and determining their signal quality based on the ones that it can receive/decode. During a call, a phone may be in communication with as many as 3 cell towers, and even then that's not terribly common.

    You're going to have bigger problems with doppler at the plane speeds. But the most fundamental issue is going to be signal propagation.

    Most modern cell towers are going to be using directional antennas. These antennas generally split a cell into 3 or more sectors. Each sector has its own antenna that dumps the majority of its power out directly in front of it with huge loss to signals along the (60, 300) degree range (i.e. to the side and behind). This is to reduce self interference with other cell towers behind the sector in question. It will also likely have significant loss to signals being emitted in an upwards direction, the direction that you would care about in a plane. This pretty much makes the question of whether or not the FAA will allow phones on planes moot. Who cares if they'll let you turn on your phone when you can't get a signal anyway?

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