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  1.    #1  
    Air & Space Smithsonian had an article this month about cell phone use on airplanes, and why use is banned. And possible hope for new "airline" modes on phones that will allow them to be safely used onboard airliners in the near future

    The truth is that portable electronic devices can emit powerful electromagnetic radiation that can muck up an aircraft's navigation and communication systems and actually endanger a flight.
    It's not availble on their website, but I have the scans here. (It's a great magazine! Well worth the subscription cost ) This article is 3 pages long:
    Page 1
    Page 2
    Page 3

    As you can see, there are a lot of antennas on a modern airliner, working at a lot of different frequencies.
    http://members.cox.net/sjfehr/phone/...ftantennas.jpg


    There are also a lot of spurious emissions- anything emitted with a power of over -120dBm has the potential of creating interference, and a typical cell phone puts out a wide range of frequencies with strengths over 1000x that level!
    http://members.cox.net/sjfehr/phone/PhoneEmissions.jpg
  2. #2  
    according to Cringley, pilots used cell phones to call home while in flight.

    Read:

    http://www.pbs.org/cringely/pulpit/pulpit20040729.html
    Felipe
    On the road to 5,000 posts
    Life is what happens between Firmware releases.
  3. #3  
    Does anyone know of any real study on this issue? If indeed Portable Electronic Devices are a real hazard, why is the no public evidence of it?

    The airlines do make money from the movies and onboard phones. Could that have anything to do with thier relectunace to disallow the use of competing technology?
  4. #4  
    If the emissions from a cell phone are so potentially dangerous I've never understood why they let them on planes in the first place. Do they have RF detection on the planes to alert when someone turns on their dangerous device? I don't think so.

    If phones are so dangerous why don't terrorists get on flights with a backpack full of cellphones, out of sight, transmitting away? If they did it enough (and it *was* dangerous) wouldn't it eventually cause a crash? Maybe this is already happening?

    If there was even a remote risk it would not be something I would feel comfortable trusting the average air passenger to manage.
  5. #5  
    Quote Originally Posted by JohnWilliams
    If the emissions from a cell phone are so potentially dangerous I've never understood why they let them on planes in the first place. Do they have RF detection on the planes to alert when someone turns on their dangerous device? I don't think so.

    If phones are so dangerous why don't terrorists get on flights with a backpack full of cellphones, out of sight, transmitting away? If they did it enough (and it *was* dangerous) wouldn't it eventually cause a crash? Maybe this is already happening?

    If there was even a remote risk it would not be something I would feel comfortable trusting the average air passenger to manage.
    I agree. Which is why I tend to lean towards the profit infringemnet motive of the airlines....if we can use our phones, they make less money.
    "Common sense is the collection of prejudices acquired by age eighteen."
    - Albert Einstein
  6. #6  
    i think the probability of cell phone radiation affecting the airplane communication system is so low that they cannot ban it. by asking you to switch it off they are reducing the chance even further...
  7.    #7  
    Have the people replying so far actually read the article I posted? It clearly states what the danger is, why its a danger, and the reasons for the cell phone ban and bans on portable electronics during part of the flight. The affect of electronics on aircraft communications is very real and frequently causes problems. The problems aren't the "OMG YOU TURNED A CELL ON THE PLA?NE WILL CRASH!!" type problems, but they do mean possible interference in cockpit headsets, interference with navigational system, etc. Not every cell phone is going to interfere with an aircraft system on every flight- but if 1 out of 1000 does or 1 out of 10,000, and its impossible for the airline to single that phone out, then it's enough to prohibit the use of all phones!

    Interference happens more than you think; the pilots just don't like to mention it because it would cause fear.

    For anyone who thinks interference is a myth:
    There's one way to explain what happened to Richard Innes, a pilot who flies McDonnel Douglas MD-88s fro a major airline. A year and a half ago, Innes was in cruise flight near Indianapolis, Indiana, when static over his headphones made it difficult to speak with his copilot. Innes then made what's known as a "PED announcement" to the cabin, asking passengers to turn off all portable electronic devices. The problem cleared up and Innes was inclined to leave it at that.
  8.    #8  
    Quote Originally Posted by Felipe
    according to Cringley, pilots used cell phones to call home while in flight.

    Read:

    http://www.pbs.org/cringely/pulpit/pulpit20040729.html
    heh, well, "do as I say, not as I do" certainly applies here! The pilots would know instantly if their cell phones were causing problems and could remedy it. This wouldn't be the case with the 200+ people in the cabin, over which they can't exert the instant control they can over their own phones.
  9. #9  
    Yes I did read the article. I have two points:

    Cirmstantial evidence either way does not mean that there is a risk or not. A real analysys is needed, but aparently no one is doing one.

    Yes cell phones have excess emmissions. Virtaully all all electronic devices, even the ones the airlines use have excess emmisions. Proper shielding, twisting pairs of wires and other normal techniques can protect sensitive equipment from these emmisions. Airplanes must use these methods to shield from TV, AM, FM, Shortwave, and other high power radio signals, and from any electrical noise from compressors, generators, or even the engines. There are so many types of emmisions that I cannot believe that non-transmitting devices such as FCC certified TVs, FM Radios, and CD players pose any real risk. The risk from transmitting devices like cell phones is probably higher, but acording to the article they are not banned because of emmisions, but because of problems that might be caused with the cell towers on the ground.
  10.    #10  
    Note that Cell Phones are banned in Hospitals and near construction sites using explosive detonators, too. It's not that interferences are any more or less likely in airplanes, hospitals or near blasting than anywhere else- but that the consequences of interference are literally a matter of life or death and the risks associated with the slight chance of interferences are that much higher.
  11. #11  
    There is supposedly testing going on now (or will be soon) to try to get cell phones approved for use in the air. Of course it's being spear-headed by Qualcomm who would benefit from this...
    http://www.usatoday.com/tech/wireles...t-phones_x.htm

    Jacobs said San Diego-based Qualcomm would spend the next two years testing whether electronic signals interfered with the jet's avionics system
    Treo 680 GSM since July 2007
    Treo 600 GSM from November 2003 through July 2007
    AT&T (formerly Cingular, formerly PacBell PCS) since September 1998
  12. #12  
    Steve--

    Thanks so much for posting that article. I'll have to admit, this issue always gets me so upset. It probably shouldn't -- but it does.

    Personally - my deep-down feelings for anyone who feels "slighted" by the airlines/government/etc. by not being able to use their cell phone during ... take a bus or a train. Stay off my plane with your phone, ok?

    Now, I don't have an EE degree - so I won't even try to debate the merits of the question "Does it really cause interference?" because .... quite frankly .... it doesn't appear it can be proven, conclusively, either way. I can't prove that cell phones definitively cause interference every single time (or even 1 in 10,000 times) they're used, but at the same time no one can prove that they definitively don't ever cause interference - ever. Even with folks like Brian Donham from Boeing spending over a decade researching such issues, he can't come up with a definitive answer.

    So, without a definitive answer - you've got two ways you can make your policy. You can err on the side of being cautious and protecting human life, or you can err on the side of convenience and let everyone use their phones, FM radios (you'd think it only receives signals, but if you understand how FM receivers work you'll realize they transmit a small signal as well), televisions, etc. I, for one, am glad that the FAA has decided to err on the side of protecting my life when I'm at 39,000 feet moving at 600 miles per hour.

    Is a single cell phone going to take down a flight? No. Do the pilots use their personal cell phones from time to time? I bet they probably do .... but they're the pilots. I have no major issue with that exception - if they saw some sort of odd problem I'd bet they would immediately turn off their cell phone, because a pilot wants to land on the ground in one piece just as much as I do. I think what the FAA is really worried about is an entire plane-full of passengers all using their phones at exactly the same time. So -- interference from 1 phone? Probably not an issue. Interference from 300 phones? That could definitely cause problems, IMO.

    For those who feel that there might be a profit motive behind things -- perhaps. But, why would the hospital industry also implement the same regulations in their facilities? Every hospital I've been in over the last few years, I was required to turn my cell phone off as I entered. Profit motive? By forcing me to go pay $.35 to use a pay phone? I doubt it. But out of courtesy to the sick pateints in the hospital whose lives are dependent on complex machinery at that moment in time - I gladly turn it off without question. And I view folks who blatanly choose to disregard this simple request as grossly incosiderate.

    If your business work is so important that you must talk while you fly, then pay for it. I've used the air-phone when needed ... it's not that bad. Yeah, it costs a couple bucks. So what. If you're just too cheap to use the air-phone, then don't call. Or take a bus. Just don't get on my flight, please....

    (let the flames begin)

    -Doug
    Toomer
  13. #13  
    I read some time ago that it's sometimes possible to get a cell signal at low altitudes, and that the carrier would not know who to bill if a call was made. Can't say I've tried it, being a good citizen and all.
    Defineitely a profit motive their somewhere.
    PS- Was in the hospital a few months ago visting a relative and the guard made me shut my cell in the loby when I received a call. Upstairs in the room the doctor was visiting the patient and got a cell phone call and didn't hesitate to talk. Didn't see any equipment go haywire either.
  14. #14  
    Quote Originally Posted by catbert00
    There is supposedly testing going on now (or will be soon) to try to get cell phones approved for use in the air. Of course it's being spear-headed by Qualcomm who would benefit from this...
    http://www.usatoday.com/tech/wireles...t-phones_x.htm
    A key reason to ban cell-phones from planes is that their signal could be picked up over a large area and hence at a large number of base stations on the ground, potentially blocking many cells. This is particularly true of TDMA systems like GSM - less so with CDMA where the code advantage can be used to discriminate wanted from unwanted signals. Note that mobile phones are banned in hot-air balloons (with no electronics) for that reason.

    The Qualcomm system would put a base station in the aircraft - hence the signals used for such a pico-cell would be very low power, and much less likely to cause interference.
  15. #15  
    I was visiting a hospital in downtown Minneapolis last year. All around were signs saying "Turn off your Cell Phone". Some signs suggested that cell phones might cause problems with equipment.

    To my amazement, looking out one window, I could count on near by buildings over 15 poles each with 4 or more cell phone antennas on them. I wondered that if my puny cell phone could cause problems, what problems would those puppies cause?

    It's my unscientific opinion that cell phones are banned in hospitals more for the benefits of the patients who probably don't want ring tones and noisy conversations going on all over the place, rather than any risk they might pose.
  16. #16  
    I was on a flight and got stuck on the tarmac in Chicago for about 40 minutes. They announced over the intercomm that it was OK to use your cell phone while we waited. Being board, I pulled out my T3 to do some e-book reading. Along comes a flight attendant and snipps at me to "Sir, please turn that device off until you depart the plane", as if my T3 was going to put out some nasty RF signals that all the other passengers talking on their cell phones wouldn't.
  17. #17  
    Quote Originally Posted by SteveFehr
    ...but that the consequences of interference are literally a matter of life or death and the risks associated with the slight chance of interferences are that much higher.
    Certainly the fair and unbiased opinion of The Register should suffice to prove the contrary...

    Mobiles in hospitals now safe: official
    http://www.theregister.co.uk/2004/07...pitals_health/
    Quote Originally Posted by Reg
    Today, though, the Medicines and Healthcare products Regulatory Agency (MHRA) issued new advice that a total ban on mobile phones in hospitals "is not necessary". Instead, it recommends that hospitals should "balance the risks of mobile phones interfering with critical devices and the desire for better communication in hospitals".
    Quote Originally Posted by Reg
    He argued that emergency services radios have a much greater risk of interfering with essential equipment, yet are allowed into resuscitation units and intensive care rooms. He cited a 1997 study, which found mobiles only affected four per cent of devices, and only 0.1 per cent were seriously affected.
    Chriz
  18. #18  
    Quote Originally Posted by jpahl
    A key reason to ban cell-phones from planes is that their signal could be picked up over a large area and hence at a large number of base stations on the ground, potentially blocking many cells. This is particularly true of TDMA systems like GSM - less so with CDMA where the code advantage can be used to discriminate wanted from unwanted signals. Note that mobile phones are banned in hot-air balloons (with no electronics) for that reason.

    The Qualcomm system would put a base station in the aircraft - hence the signals used for such a pico-cell would be very low power, and much less likely to cause interference.
    This is the most sensible reasoning that I have come to support. I can't imagine cell phone towers being designed to handle mass inter-tower negotiating. Really it's not that common for a person to be within range of over a dozen towers, but in an airplane one would.
    "The danger from computers is not that they will eventually get as smart as men, but that we will agree to meet them halfway." -Bernard Avishai
    "Computers are a lot like air conditioners - they both work great until you open windows." -Anonymous

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