# Want to use your iPad during takeoff? Tell the FAA



## CHamilton (Aug 28, 2012)

This has been making the rounds among the tech blogs, but I thought AU travelers might be interested.

Want to use your iPad during takeoff? Tell the FAA



> The Federal Aviation Administration is asking for opinions on the use of portable electronic devices on flights — including during an airplane's take off and landing. The agency released a document today asking the public and other interested parties to comment on the use of devices that might include iPads, Kindles (a amzn) and other gadgets — a topic that has become more pressing as more people rely on such devices while traveling.
> 
> The FAA is seeking comment from passengers, airlines, flight attendants and the makers of electronic devices on a variety of topics such as procedures for testing and gathering data about how portable electronic devices interact with aircraft systems, how to build avionics systems and aircraft that don't react to Kindles or iPads, and how to build gadget that wouldn't cause such interference. The agency also wants passengers to weigh in on topics like whether or not voice calls on aircraft would be distracting or staring at your e-reader might make you less likely to pay attention to the safety briefings at the beginning of each flight.


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## Devil's Advocate (Aug 28, 2012)

History already tells us that portable electronics will not bring down a commercial jetliner. If they were capable of that then numerous aircraft would have already crashed by now as a result of phones and other devices being left on both intentionally and by accident. However, science tells us that having a bunch of phones trying to transmit and receive in a small area enclosed by metal raises the nominal radiation levels above approved levels. In addition, having a bunch of people chatting away on their phones while in the air (as some airlines are proposing) is both distracting and annoying. Personally I have no problem with people quietly using iPod's or iPad's or Kindle's or even GPS receivers during takeoff and landing, but I will not condone use of phones while traveling in public. You want to babble all day on your phone? Then you are free to drive. Otherwise you should respect the personal space of those around you and let them travel in peace.


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## Trogdor (Aug 28, 2012)

I don't think e-readers would make people less likely to pay attention during the safety briefings. Books and magazines are not prohibited at any time during the flight (including taxi, takeoff and landing) and there is no difference between a book and an ereader, as far as attentiveness of the reader is concerned.

I think phone calls would be a bad idea, though.

People on cell phones already speak louder than they normally would have to. While I don't know all of the scientific details on why that is, I gather it's because we don't have the same audio feedback of hearing our own voice on a cell phone like we do elsewhere, and also because the phone itself is hard to hear (which then makes people subconsciously speak louder, I guess). That's just in normal surroundings. When you're on a plane, there's lots of ambient noise (namely, the engines) which make the environment even louder. People will inevitably compensate for that the way they do when trying to converse in any loud environment, namely, by speaking even louder.

If they started allowing phone conversations on planes, then airlines would have to start offering "quiet zones" (or, conversely, cell phone sections) on planes where cell phones are prohibited (or allowed).

To sum up:

Small inaudible (except to user) electronic devices: yes

Cell phones: no


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## JayPea (Aug 28, 2012)

If I'm not mistaken, the FCC and not the FAA regulates the use of cell phones on planes. Thus the possibility of easing the restrictions on portable cellular devices would not extend to phones unless the FCC changed their regulations. Which I hope they don't. I get tired of hearing inane conversations about absolutely nothing of importance blabbed at top volume for all to hear.


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## the_traveler (Aug 28, 2012)

I don't fly much (if at all), but when I did/do, I agree cell phones are a bad idea. There is enough noise on a plane anyway. iPads, etc... I see no problem, unless they are making noise. Have the rules just like on trains.

As an aside, I once took a train in BC from WAS to KIN. Soon afterwards, at least 1/3 of the car was blabbing away on their cell phone, so it was anything but quiet!




(The only reason I was in BC was that it was included in the AGR award - I had just left a sleeper.) The main problem with this is that we were just boarding in WAS, the run began in WAS and the train was still at the platform in WAS! We're all those calls really that important?


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## Anderson (Aug 28, 2012)

the_traveler said:


> I don't fly much (if at all), but when I did/do, I agree cell phones are a bad idea. There is enough noise on a plane anyway. iPads, etc... I see no problem, unless they are making noise. Have the rules just like on trains.
> 
> As an aside, I once took a train in BC from WAS to KIN. Soon afterwards, at least 1/3 of the car was blabbing away on their cell phone, so it was anything but quiet!
> 
> ...


Oh, that's _nothing_. Hop in First Class on the Acela on a weekday and it can be like being stuck on a trading floor: Lots of suits, lots of phone calls...just in 2-1 seating with decent food.


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## Trogdor (Aug 28, 2012)

JayPea said:


> If I'm not mistaken, the FCC and not the FAA regulates the use of cell phones on planes. Thus the possibility of easing the restrictions on portable cellular devices would not extend to phones unless the FCC changed their regulations. Which I hope they don't. I get tired of hearing inane conversations about absolutely nothing of importance blabbed at top volume for all to hear.


Actually, they both do.

FCC regulates it due to potential problems with wireless networks on the ground (I don't know the details on that).

FAA regulates it due to potential for interference with aircraft communication and navigation systems.


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## jis (Aug 28, 2012)

Anderson said:


> the_traveler said:
> 
> 
> > I don't fly much (if at all), but when I did/do, I agree cell phones are a bad idea. There is enough noise on a plane anyway. iPads, etc... I see no problem, unless they are making noise. Have the rules just like on trains.
> ...


If Texan is right about the radiation thing (which I don;t think he is) then all those suits in Acela First Class must be coming out glowing at the end of it all :lol:


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## leemell (Aug 29, 2012)

Trogdor said:


> JayPea said:
> 
> 
> > If I'm not mistaken, the FCC and not the FAA regulates the use of cell phones on planes. Thus the possibility of easing the restrictions on portable cellular devices would not extend to phones unless the FCC changed their regulations. Which I hope they don't. I get tired of hearing inane conversations about absolutely nothing of importance blabbed at top volume for all to hear.
> ...


The FCC doesn't like it because the cell phone networks are designed for phones to be used near the ground and be in contact with at most three towers and usually just one. When taken aloft, they can connect with many more cell towers and tie up a channel on each greatly reducing the network capacity.


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## Devil's Advocate (Aug 29, 2012)

jis said:


> If Texan is right about the radiation thing (which I don;t think he is) then all those suits in Acela First Class must be coming out glowing at the end of it all :lol:


It is not yet known if or how much damage could result from a lifetime of close interaction with modern cell phones, but it's entirely possible that if damage is indeed occurring it could be substantially worsened by placing many transmitters and receivers into what amounts to a tightly packed aluminum tube. Early testing with subway cars appeared to result in radiation levels above and beyond previously tested levels. To my knowledge there is not yet much in the way of formal studies on this topic, which is why I would like to see more information gathered and distributed.

What is not in dispute is that we live in an era where cancer rates are increasing steadily. It's quite likely that our ever increasing cancer rates are a cumulative effect that results from many potential sources, which means that it will likely be very difficult to explain to the average citizen in a way they can understand and become motivated to address. In any case the first step is determining exactly how safe or how dangerous each potential source is to the best of our technology and understanding. At the moment cell phones are already suspected of increases in glioma and acoustic neuroma brain cancer in routine mobile phone users. Additional peer reviewed studies should help us to determine where we should focus our efforts to help avoid creating a society full of cancer patients depending on the world's most expensive health care system.



leemell said:


> The FCC doesn't like it because the cell phone networks are designed for phones to be used near the ground and be in contact with at most three towers and usually just one. When taken aloft, they can connect with many more cell towers and tie up a channel on each greatly reducing the network capacity.


I don't think it works that way. If you ever try to turn on your phone while at cruising speed and altitude you'll never connect to anything. You're doing close to 500MPH at 30,000 feet. Neither the phone or the tower has any hope of connecting under those circumstances. It's just too far and too fast to work, even for text messages.


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## leemell (Aug 30, 2012)

Texas Sunset said:


> leemell said:
> 
> 
> > The FCC doesn't like it because the cell phone networks are designed for phones to be used near the ground and be in contact with at most three towers and usually just one. When taken aloft, they can connect with many more cell towers and tie up a channel on each greatly reducing the network capacity.
> ...


To quote --

"A U.S. ban on airborne use of cell phones has been in place for 20 years because of concerns transmissions would interfere with cellular networks on the ground. While many airlines now offer Wi-Fi access via portable electronic devices from laptops to smartphones, cellular voice and data services on domestic airlines fall under that Federal Communications Commission ban."


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## Devil's Advocate (Aug 30, 2012)

leemell said:


> Texas Sunset said:
> 
> 
> > leemell said:
> ...


I've been flying with cell phones since the analogue era back in the 1990's. No phone I've ever owned, analogue or digital, has ever connected to any towers while in the air at cruising speed and altitude in all that time. The FCC can say whatever they want, and maybe they know something I don't, but my experience among all the major providers all over the country has been entirely consistent. Mobile phones are useless in the sky and they never connect to anything.


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## leemell (Aug 30, 2012)

Texas Sunset said:


> leemell said:
> 
> 
> > Texas Sunset said:
> ...


They do not have to connect to cause a problem. This article explains the techniques and physics from which this results

"The ... FCC currently prohibits the use of mobile telephones aboard _any_ aircraft in flight. The reason given is that mobile phone systems depend on channel reuse and operating a phone at altitude may violate the fundamental assumptions that allow channel reuse to work.

The FCC is also concerned that the use, or even non-use, of a powered cell phone could cause disruption to the cell systems' towers and has banned their use.

Mobile telephones are intentionally designed with a low power output. A tower is the center of a "cell" and due to attenuation with distance (inverse square law) cell phone transmissions can usually be received only weakly by towers in adjacent cells and not at all in cells farther away (non-adjacent cells). This allows the channel used by any given phone to be reused by other phones in non-adjacent cells. This principle allows tens or hundreds of thousands of people to use their phones at the same time in a given metropolitan area while using only a limited number of channels.

Channel reuse works because a mobile phone on the ground will only have one "closest" tower that can possibly use a particular group of frequencies, CDMA codes, or time slots. The software that manages the system assumes that the signal from a phone on a particular tower can, on other towers, only be "heard" at greatly reduced signal strength. The frequency, code, or time slot used by the phone can therefore be reused by other phones on other towers.

In the old analog cell system a channel was simply a frequency pair: There were seven groups of 35 channels each and no two adjacent cells used the same channel groups. Modern CDMA and TDMA systems are more complex: A channel in TDMA is a frequency pair, and a time slot, and a channel in CDMA is a spread spectrum key but the principle of channel reuse still applies.

If a mobile phone is operated from an aircraft in flight above a city these assumptions are no longer valid because the towers of numerous different cells may be about equidistant from the phone. Multiple towers might assume that the phone is under their control and the phone could be assigned a free channel by one tower but could also be heard on other towers using the same channel group. The channel might already be in use on those other towers and could cause interference with existing calls. Even if the software can cope with hearing the same phone on multiple non-adjacent towers the result at best is an overall decrease in system capacity.

An additional concern is the output power of the mobile handset. Because the towers might be miles below the aircraft the phone might have to transmit at its maximum power to be received. This will increase the risk of interference with electronic equipment on the aircraft."


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## George Harris (Sep 9, 2012)

If an aircraft's electronics are so fragile that cell phones and other electronics in widespread public use can interfere with them we have a major problem that needs fixing NOW. Because, if true, it would be way too easy to deliberately cause interference.


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## leemell (Sep 9, 2012)

George Harris said:


> If an aircraft's electronics are so fragile that cell phones and other electronics in widespread public use can interfere with them we have a major problem that needs fixing NOW. Because, if true, it would be way too easy to deliberately cause interference.


It is not that they are fragile, but that the signals they they operate from are quite low when they reach the aircraft and the PE transmitters while not very powerful, are very close.


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