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  1. #41  
    Originally posted by randyg
    while i don't pretend to understand how an airplane works, it seems that if a simple little cellphone signal could cause the plane to lose control (or whatever), what about all the other signals out there in the air that they can't control. what if some kids rc airplane control suddenly took over a 747? it's just crazy talk, that's all.
    The problem comes from the fact that todays aircrafts are loaded with electronic equipments, and there are long and mostly unprotected buses transmitting the signals between the various computers/systems controlling the aircraft. If you have any kind of device which can emit radio waves (like cell phones, of course, but also CD & DVD players because of the builtin laser and associated electronic, it seems), and that device happens to be close to one of these buses (there are many of them under the floor, or above the overhead compartments), chances are that it could cause some sort of interferences and that may disturb the transmitted signal. Not that it would let you completely take wirelessly control of the plane, of course, but it might be enough to cause a few seconds of disturbances.

    The key point here is the distance between the aircraft sensible electronic parts and the device potentialy causing the interference: even a (relatively) small power can cause troubles at such close range, while a strong radio transmitter located on the ground would be harmless even during take of and landing.

    This of course is a bigger problem near the ground (landings and take-off), but also in some areas where the heavy air traffic has caused the vertical separation of the aircraft to be only a tiny 1000 feet. An unexpected climb, if there's another aircraft just above you, could lead to a dangerous situation...

    Now of course, this obviously doesn't apply to devices like electronic watches or non-wireless PDAs, but the problem is that there are so many devices on the market that it's almost impossible for the flight crew to know which is (potentially) dangerous and which isn't, so they usually go on the cautious side and forbid you to use anything that remotely looks like it can emit radio waves.

    I'm sure that in a couple of years from now, when every laptop computer on the market will feature bluetooth and wifi, they'll have to do something about that problem, if only because the people traveling in business or first class expect to be able to use their laptops during the flight for some serious work (not that the economy class traveler don't also do that, but since they pay less, they might not have the same influence! ). So I suppose that the airlines will basically either have the aircraft somehow protected from this problem (cable & IC shielding, but that would add a hell of a weight to the aircraft, and cost a lot of money!), or install some wireless emission detector (imagine a red light flashing above your seat, and a loud buzzer ringing if you happen to turn on (or forgot to switch off) any wireless device in flight...

    Meanwhile, as a pilot I've used my (non wireless) PDA in the cockpit countless times with no particular problems, even during landing and take off (when I'm not on one of the front seats, of course!), but whenever I travel in the cabin as a passenger, I always switch it off when requested by the flight attendants, regardless of the fact that I know this is harmless... It's just not worth opposing their authority in flight. Better try to do some lobbying on the ground, IMHO!
  2. #42  
    Originally posted by BrianV
    If the phone can't see the tower, then the tower can't see the phone. Even though the tower has WAY more power, it's added power increases its receiver sensitivity.
    Just because the phone can't see the tower does not imply that the tower can not see the phone, and vise versa. In an airplane situation he phone won't see the tower because of the high upward angle of the tower and the use of directional antennas at the the towers limiting the upward angle that the tranmission will go. Cell phone receiver sensitivity is also not nearly as good as the cell towers. The tower could see the phone though since it has the better receiver sensitivity and can amplify the incoming signals much more than a Cell phone can amplify the signal from the tower. Cell phone transmission is omni-directional so it is transmitting at 360-degrees both horizontally and vertically (although the vertical won't be a full 360). This can allow numerous towers to see your signal while in the air even though you won't see them, and since the cell system is really only designed to see you at about three to four towers, it will get confused and could cause other issues.
  3. #43  
    http://www.caa.co.uk/srg/default.asp?page=1347

    http://www.caa.co.uk/docs/33/CAPAP2003_03.PDF

    http://newsroom.cisco.com/dlls/ts_011503.html

    My 2 cents. This first link is a summary from the CAA, the UK flight safety org, the second is its report in damnable PDF format. The third is Cisco piece describing their work with Lufthansa using onboard wi-fi.

    BKMD
  4. #44  
    http://newsroom.cisco.com/dlls/video_audio_archive/?all

    Scroll down and select the Lufthansa movie. Good description of the technology.

    (Please ignore the "Wireless Doctors" movie where the doctor is wearing a red rubber nose. One Patch Adams is enough.)

    BKMD
  5. #45  
    The Boeing information site is here:

    www.boeing.com/connexion/
  6. #46  
    Originally posted by lnichols


    Just because the phone can't see the tower does not imply that the tower can not see the phone, and vise versa. In an airplane situation he phone won't see the tower because of the high upward angle of the tower and the use of directional antennas at the the towers limiting the upward angle that the tranmission will go. Cell phone receiver sensitivity is also not nearly as good as the cell towers. The tower could see the phone though since it has the better receiver sensitivity and can amplify the incoming signals much more than a Cell phone can amplify the signal from the tower. Cell phone transmission is omni-directional so it is transmitting at 360-degrees both horizontally and vertically (although the vertical won't be a full 360). This can allow numerous towers to see your signal while in the air even though you won't see them, and since the cell system is really only designed to see you at about three to four towers, it will get confused and could cause other issues.
    You're right about the receiver sensitivity being like an amp for the incoming signal, but at the same time the tower can TRANSMIT that amplified signal and therefore the receiver on the cell phone does need to be as sensitiv, however the amplified signal is not being transmitted up in the air towards an airplane.

    So if the phone can communicate with the tower, then the tower can communicate with the phone, and vice-versa. And if one can communicate and the other can't, then you're definitely not going to be getting cellular service anyways.
  7. #47  
    Obviously if the phone can't see the tower, then you are not going to have service as it requires bi-directional communication. But if the tower can see the phone, and if a ton of towers see the same phone then it can cause issues.

    I was sitting beside of this one guy on a plane once that had his phone out. He asked me why he couldn't get a signal. I laughed and had to explain how cell phones worked and why it is illegal to operate a cell phone in an airplane. He left it on anyway as he didn't really seem to care.
  8. #48  
    I have indeed spoken to someone who was on a plane at cruising altitude on a cell phone (digital GSM service, not analog.) This person didn't know the rules and called me from the flight. Don't know how it happened, but it did. Fire away.
  9. #49  
    Another note: an author who has traveled on Air Force One related that the cell phones are on and in use constantly on that bird, takeoff, landing, or otherwise. Clearly, this plane could have quite a bit of protection that commercial airliners don't have, so that may not mean a whole lot.
  10. #50  
    Originally posted by King Hippo
    although I don't know if wifi would make them feel any more comfortable about having the device powered on.
    It wouldn't, mostly because they believe their own propaganda. Most of them really believe that it is an FAA regulation and that it really is about interference with navigation. In fact, it is an FCC regulation and is about interference with ground-based cells.

    Incidentally, my understanding is that the new Boeing on-board internet service will support both wired ethernet and Wi-Fi. It is also my understanding that a number of Lufthansa planes are already fitted out. Can anyone confirm?
  11. #51  
    Yes, Boeing and Lufthansa are doing some development (and in the case of Lufthansa, starting to deploy) WiFi in the Sky. Check this http://www.newswireless.net/articles...9-flight.html, it's a rant (a bit like in our forum ) between the ones for and against it BUT it also includes a link to an article on Lufthansa maiden WiFi flight, between Washington DC and Frankfurt. The test was in January and Lufthansa made an announcement in May detailling deployement in 80 aircrafts.
    Since people have problems with my Einstein quotes, I will now quote my true hero: Homer Simpson.

    "Doh !'
  12. #52  
    Originally posted by jaginger
    Another note: an author who has traveled on Air Force One related that the cell phones are on and in use constantly on that bird, takeoff, landing, or otherwise. Clearly, this plane could have quite a bit of protection that commercial airliners don't have, so that may not mean a whole lot.
    If I had to take a guess, Air Force One should be Electromagnetically shielded like the Navy airborne com centers to protect it from an EMP (electromagnetic pulse). This will protect all of the electronics on the plane from EM interference.
  13. #53  
    It is true and up and running, Lufthansa Wi Fi that is -
    A friend of mine has taken that trip, it seems that there were special wifi hostesses who would "lend" you a WiFi enabled laptop for the duration of the flight, in the event you were wifiless.

    I was Instant messaging with him in Real time very slick,

    They also seem to be very well priced a flat fee (i dont recall if it was 10 or 15 euro ) for the entire flight(Although they were not charging when he flew!

    L E
  14. #54  
    There was a recent announcement that the FAA will be reviewing cell phone use and was to report back by 2006 I belive. So maybe in my lifetime I can get that all important call on the flight to never never land.
  15. #55  
    While they may decide that interference is not an issue, I sincerely hope they do NOT EVER allow cell phone use during the flight. Can you imagine 30-50 people (on a plane of 250 or so) yakking away on their phones the entire flight?

    That's more interference than I'm willing to put up with!
  16. #56  
    Originally posted by jaginger
    While they may decide that interference is not an issue, I sincerely hope they do NOT EVER allow cell phone use during the flight. Can you imagine 30-50 people (on a plane of 250 or so) yakking away on their phones the entire flight?

    That's more interference than I'm willing to put up with!
    Or even worse a plane full of Nextel 2-way beeps and the conversations that go with them. I hate when people use the PTT in public place and I have to listen to both ends of the conversation.
  17. #57  
    Originally posted by jaginger
    While they may decide that interference is not an issue, I sincerely hope they do NOT EVER allow cell phone use during the flight. Can you imagine 30-50 people (on a plane of 250 or so) yakking away on their phones the entire flight?

    That's more interference than I'm willing to put up with!

    Most people wouldnt be making calls, but rather business people would be recieving them...i think you're blowing it way out of proportion...
    Treo 300, Treo 600 - Sprint

    I dream in code and TCP/IP sequence numbers.
  18. #58  
    Uhh, no I'm not blowing it out of proportion. Business people are going to be making more calls than they receive. Plus, it doesn't matter whether they're making them or receiving them -- they're talking out loud either way!
  19. #59  
    of course you're blowing it out of proportion...tell me when you sit down in a plane, how many people do you see in suits...maybe one or two, how many with laptops, one or two, hmm theres not a lot is there? You act like the use of cell phones on a plane is like a terrorist attack, and people have respect, they dont talk loudly, they'd talk as loud as you do with the person you sit next to...that's not as bad as you claim it is.
    Treo 300, Treo 600 - Sprint

    I dream in code and TCP/IP sequence numbers.
  20. #60  
    Its rude...I run a business that keeps me glued to a cell phone...but there is a time and a place that its not appropriate...too many people have no common courtesy...be it in restaraunts, stores... and plane will be no exception. Heck, people are on edge enough when flying! Dont think it was "blown out of proportion" at all.
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