Talk:Mobile phones on aircraft

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The critical reason phones are banned on aircraft is when they search for a repeater station, they intefere with the electromagnetic NAV instruments such as NDB's, DME's etc. Most cells cannot be used even if turned on because of the heavy dampening effect caused by noise & wayward frequency cancellation technologies used in the aircraft's structure. This is the breifing given to pilots regarding cellphone use, for more technical info you should check with an engineering outfit. - Molloy

That is a nice theory; however, pilots often use cell phones during flight. FAA FAR's are legal requirements, but they may be ignored in times of emergency, though it is unlikely that using a cellphone in flight is the answer to an emergency. In the case of cellular phones, if the pilot is the only person with a cellular phone turned on, he can easilly turn it off if he or she notes interference.

From the first few paragraphs this article reads like it was written by someone with a personal vendetta against the banning of mobile phones on aircraft, i dont know enough about the subject to rewrite it, however. 195.172.220.162

Contents

[edit] Explaining my reversion

I came to this page because I was looking through contributions from an anonymous IP address which had vandalized the Adolf Hitler article today. I saw an edit from 24 November, and accidentally clicked the rollback button, while intending to click the diff. I tried to stop my edit, but it was too late. I would not have rolled back without checking that it was vandalism, especially since the edit could be from a completely different person. I then rolled back my own edit. I am not familiar with this article, and have no view on whether or not the NPOV tag should be on it. Someone else should look into it. I simply rolled myself back because I had not intended to use rollback. Apologies. AnnH (talk) 15:26, 28 November 2005 (UTC)

[edit] New title?

Shouldn't the title be "Use of Mobile phones on Commercial Aircrafts"? As far as I can see the whole article deals with that rather than the actualy mobile phone on aircraft. --antilived T | C 22:57, 10 December 2005 (UTC)

[edit] Cleanup

I've done some limited NPOV editing of the article. What do you guys think? Werdna648T/C\@ 07:09, 31 December 2005 (UTC)

[edit] Cingular Against Phone Use On Planes

While I'm not sure what their current policy is, this article from last June [1] says that Cingular is in favor of keeping the ban on cell phone use on airliners, due to the fact that people talking on their phones can be irritating to those around them.--Raguleader 18:38, 28 February 2006 (UTC)

[edit] Billing Idea

I can in no one verify this but I heard that companies can not properly bill people who use cell phones in planes.Tjb891 20:28, 1 June 2006 (UTC)

I work for O2 in the UK. I don't see why there would be a problem with billing. When your phone is connected to a service provider, it is connected, the billing is not affected. My other point is that because we don't know whether mobile phones interfere with sysetms, we should not use them until we know they DO NOT interfere. I accidentally left my phone swithched on on a flight from JFK to Heathrow and I am still here! But we should not play "God" with the lives of others and should be sensible.

--81.152.245.125 23:19, 13 July 2006 (UTC)

[edit] Frequency Reuse

DylanW removed the following section from the article a few months ago:

==Frequency Reuse==
Perhaps the greatest issue is, however, the principle of frequency reuse. Mobile phones are designed to transmit only as far as the closest cell tower. This allows the same frequencies to be used by different phones in any non-adjacent cells, a key component in allowing tens or hundreds of thousands of people to use their phones at the same time in a given metropolitan area. From an altitude, distant cells are visible to the mobile with no line-of-sight attenuation from intervening obstacles. Because the cells are in some cases several tens of thousands of feet below the aircraft, the phone will transmit at its maximum power (also increasing the risk of interference with electronic equipment on the aircraft), which will also significantly shorten its battery life. Since the phone is occupying its frequency and channel in all of the cells its signal reaches to (which could be many cells over many miles), that frequency and channel cannot be used by any other phones in any of those cells because of interference, resulting in an overall decrease in the cellular system's capacity. This is the primary reason the U.S. Federal Communications Commission prohibits the use of mobile phones in the air. (The U.S. Federal Aviation Administration is more concerned with interference to aircraft systems.)

I had added much of this paragraph to the original mobile phones article (which was subsequently moved to this article) based on several news articles as well as information from people inside the aviation community. A quick Google search for the topic brings up several sources for the info I posted. Here's a clip from a CNET article discussing the subject:

Why the cell phone ban?
The cell phone ban went into effect in 1991, mostly to eliminate the possibility that cell phone calls on airplanes would interfere with cell conversations on the ground, as well as with the airplane's radio communications.
The FCC cited effects of "frequency re-use," which is a fundamental cell phone principle that's helped mobile phones proliferate worldwide. The signal from a cell phone doesn't go on forever; the energy to propel it dissipates after a number of miles, and it dissipates more quickly if it bounces off buildings, hills and other obstacles. This allows the same frequencies to be re-used by operators in different markets sometimes just a few miles apart.
A cell phone signal falling to Earth from a phone aboard a plane encounters no significant obstacles to slow it down, so it's strong enough to reach the ground and find a network on its particular frequency. But if the airwaves belong to a different operator, there's likely to be "noise" and other forms of interference for everybody, the FCC believes.

DylanW put the reason for his edit as "rm section: its basis for its conclusions, "the phone is occupying its frequency and channel in all of the cells its signal reaches to", is false)." Perhaps the idea that using cell phones from the air reduces the overall cellular system's capacity IS a falsehood. Regardless, that argument is the primary one the FCC is basing its decision on, so regardless of whether it is true or not, I believe it deserves discussion in this article (albeit perhaps modified from the original version above--perhaps to indicate that this is the FCC's argument, not necessarily reality). Unless someone can show that the FCC has since rescinded that argument, I plan to add back that paragraph (with some edits). I will attempt to search for a verifiable source (perhaps a paper published by the FCC) quoting their argument to lend credence to my edit.

I'm not saying that the idea is true; I'm saying that as long as the FCC says it believes it is true, it should be discussed, even if it is false. The reality of the principle is a separate issue that can also be discussed by someone more knowledgeable about radio frequencies and electromagnetic interference (and/or studies and reports that discuss the principle).

I'm not disputing that many are against cellular usage in aircraft due to potential disturbances to navigational equipment, etc. There are TWO major federal agencies that have enacted bans on cellular usage onboard aircraft: the FCC and the FAA. The FAA implemented the ban because of concerns of interference; the FCC's ban is due to what I've said above. Both agencies (and perhaps others as well) will need to modify their regulations regarding cellular usage before mobile phones will be able to be used on aircraft. The FAA could find that cellular frequencies do NOT cause interference, but as long as the FCC believes that frequency reuse will be harmed, mobile phones will not be allowed on aircraft in the U.S.

This is my interpretation of the case based on my reading and research. As always, you are welcome to show where I am wrong--just support your challenges. I also believe it is in the spirit of Wikipedia to provide a detailed explanation/argument before removing an entire substantial paragraph, which DylanW did not do.

Sorry for being cranky--I'm a bit tired at the moment! Perhaps I'll be more cheerful come morning... cluth 02:23, 18 July 2006 (UTC)

I think this is well written and what I have heard from my aeronautics professors at college. So why is there no mention of this in the actual article? If I don't see any good reasons in the next day or so, I am going to just add it back. Like CLuth mentioned, even if the conclusions are false, we should mention what the FCC says.

[edit] There are 3 potential reasons for the non-use of mobile phones in aircraft

mobile phone types

GSM TDMA phones cause more problems to sensitive equipment than CDMA phones. This is because the GSM phones actually transmit quite high powered "pulses" of RF energy, typically several watts. A CDMA phone will only produce a maximum output of +22dBm (slightly less than 200 milliwatts). This will explain why a GSM phone will cause a loud buzz if placed near any audio equipment while being used on a call. Due to its much lower power output, a CDMA phone is less likely to cause this problem.

There are 3 primary concerns related to the use of mobile phones in aircraft.

1. The potential high energy pulses from some phones will effect the sensitive navigational and audio equipment on an aircraft.

2. A mobile phone situated thousands of feet in the air could have an effect on the phone carriers network of base stations on the ground. This is primarily because of frequency re-use as mentioned in the above information from cluth.

3. The antenna systems used on the phone carriers base station networks are designed to work with signals from either down or out from the base station (and not up). As the base stations often use very high gain and/or directional antennas, not much of the signal from the base station is radiated up towards aircraft flying above (or received at the base station from a mobile in an aircraft). As a mobile phone in an aircraft would be receiving a weak signal, it will automatically "turn" its transmit power up to maximum in an attempt to connect to the base station on the ground, hence creating the worst effect on the aircrafts sensitive systems.

While CDMA phone technology is more capable of dealing with frequency re-use, the base stations are mainly on the same RF channel (frequency), the base station antenna situation mentioned above will prevent the phones from working effectively. --Ericdog 03:38, 27 July 2006 (UTC)

3a. It's also the case that a phone moving at over 100 mph to or from a base station is going to have problems due to Doppler shift. This sounds far-fetched, as the frequency shift is not that many Hz -- but all digital phone systems use a modulation scheme that includes phase shift keying, and the Doppler shift is more than enough to corrupt the incoming data by changing its phase. The towers do have Doppler shift compensators that are good to about 100 mph but they can't begin to cope with 500 or 600 mph! Of course, just because the a/c is moving at 500 mph doesn't mean you're necessarily moving to or from the tower you're hitting at that speed; if the tower is abeam of the aircraft and at a moderate distance the relative speed may be quite low (of course, the distance is a problem too). The point though is that it's yet another reason why mobiles are just not going to work reliably at cruise speed and altitude.

The systems that are being experimented with do NOT involve letting pax just fire up their phones in flight; they work by installing a "microcell" in the a/c. So the pax's phones communicate with the microcell (using extremely low transmit power since everything is inside the a/c metal shell), and the microcell's external radios communicate with its own ground network or satellites using links that aren't bothered by the a/c's movement, just is done for the seatback phones today. Jeh 07:29, 1 August 2006 (UTC)

[edit] Aeroplane Mode

Not sure how relavent this is, but on all the flights I have been on recently (from the UK to Cyprus) the cabin crew have request that all phones be switched off even if they do have an 'In-flight mode'. --82.37.34.177 17:57, 16 August 2006 (UTC)

This is very interesting, as, when "in flight mode" is selected on a mobile phone, the whole RF (radio frequency) section is disabled and the phone can not transmit any signals. It would seem like an over-reaction on the part of the airline company.. Ericdog 12:30, 19 August 2006 (UTC)

[edit] Links to reports and other information

I'm not going to get into editing this article, but here are some links to relevant reports - make of them what you will. Jeh 20:17, 20 July 2006 (UTC)

http://asrs.arc.nasa.gov/report_sets/ped.pdf

http://www.avionicswest.com/myviewpoint/airlinecellphone.htm

http://www.airnig.co.uk/emi.htm

http://aviation-safety.net/database/events/ped/ped-case.htm

http://www.rvs.uni-bielefeld.de/publications/Incidents/DOCS/Research/Rvs/Article/EMI.html

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20010066904_2001108092.pdf

http://www.caa.co.uk/docs/33/capap2003_03.pdf

http://web.archive.org/web/20031218092141/http://md-l.amulation.com/archive/199708/msg00020.html

http://www.aviationnow.com/avnow/news/channel_awst_story.jsp?id=news/VIEW04136.xml

http://www.airlinecrew.net/vbulletin/archive/index.php/t-168185.html

http://asrs.arc.nasa.gov/callback_issues/cb_237.htm (last two items)

http://eep.burdell.org/tech/ped2.php

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