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Last Updated: Monday, 26 July, 2004, 10:14 GMT 11:14 UK
'Hi, I'm on the plane'
By Jonathan Duffy
BBC News Online Magazine

Qualcomm's chief executive Irwin Jacobs
Testing American Airlines' new in-flight mobile phone system
If mobile phones are banned on planes, what's this man playing at? And why do some airlines prohibit Gameboys, but others don't? As the great summer get-away begins, travellers are no doubt confused. But change could be on the way.

"Hi, I'm on the plane."

Soon mobile phone users could be mouthing just such a greeting into their handsets, while reclining at 30,000ft.

Until now, flying has been one of the last bastions of tranquillity in the almost unmitigated conquest of mobile phones around the planet.

But earlier this month American Airlines demonstrated a new in-flight phone system that could be introduced in two years time. Airbus is working on a similar idea.

Some airlines already offer the next best thing - on-board wireless internet access for laptop users.

Yet at the same time as passengers on one plane are merrily zapping e-mails to friends on terra firma, travellers on another flight are banned from so much as one round of Pokemon on their Gameboy Advance.

Mobiles: banned outright by most British airlines; some US carriers allow use during taxiing
Laptops: banned during take-off and landing. Some airlines have on-board wireless networks
iPods/Gamesboys etc: mostly banned below 10,000ft by UK and US airlines
The rules governing the use of electronic gadgets on flights are as complex as they are contradictory.

Most UK airlines forbid the use of mobile phones on planes at all times, although some will relax the rules if there is a prolonged delay on the Tarmac.

The reason is two-fold: radiowaves emitted by handsets can interfere with the two-way radio used by pilots, and they can skew the avionics - the on-board systems which control the plane.

However, in the US passengers get more leeway after several airlines last year allowed use of mobiles during taxiing.

Other gadgets, such as laptops, MP3 players, palm tops and pocket video games are generally allowed outside of take off and landing, although, for example, the Irish national carrier Aer Lingus curiously prohibits CD players but not laptops (which house CD players). It is changing these rules.

Bluetooth, Wi-fi and a host of other emerging wireless technologies only muddy the picture further.

The various policies are down to the fact that in the UK and US at least, airlines tailor their own rules based on national guidelines.

Boy listening to CD player
CD players, allowed on some airlines, but not on others
Some passengers are highly sceptical though and have seized on inconsistencies to claim that airlines are relying on hunches rather than hard science. Disputes with cabin crew are one of the biggest causes of air rage.

In the US, a team of aviation specialists has been trying to come up with a more coherent policy.

Later this year it is expected to recommend new rules which, according to Boeing's Dave Carson, who sits on the panel of experts, could open the door to in-flight mobile phone systems such as that trialled by American Airlines, and more wireless internet systems.

But how much of a danger are mobiles and other gadgets to an aircraft's safety?

It's a hotly debated issue. After all, on any given flight there's always a handful of passengers who simply forget to turn off their mobiles. Yet last year the US body which governs aviation safety said there had never been an accident caused by interference by passenger gadgets.

However, research published last year by the British Civil Aviation Authority (CAA) found mobile phone signals skewed navigation bearing displays by up to five degrees.

The CAA says it has documented a number of incidents of electronic devices interfering with on-board avionics.

All electronic devices emit electromagnetic radiation. Some, like mobile phones, do so intentionally in order to reach a base station. Others, like CD players, do so unintentionally and have lower emissions levels.

Baby crying
Pilots over Luton picked up cries from a rogue baby monitor
When two devices are close by the electronic pulses can interfere with each other, and theoretically cause a malfunction. The potential for this was highlighted last year when pilots flying over Luton airport picked up the sounds of a crying baby as they tried to reach air traffic control. The problem was isolated to a rogue baby monitor in a nearby house.

Modern electronics have made matters worse. Digital gadgets like CD players emit more than old-fashioned personal stereos while the latest planes have substituted old fashioned hydraulics for microchips.

In addition, mobile companies say using phones on planes can play havoc with their ground networks, because the antennae can't cope with relaying the signal from a phone which is travelling at 500mph.

Yet the idea of a laptop inadvertently downing a plane is unlikely, says Peer Kerry, who heads an international panel on radio interference.

"In reality there appears to be very little problem. During my time I've never received any requests from the CAA or airlines to reduce emissions from these types of products. If there had been serious worries they would doubtless have come to us to discuss it," says Mr Kerry.

"Airlines have to be over-cautious, but that's no bad thing. No matter how small the risk, no one wants to be responsible for a plane falling out of the sky."

Add your comments to this story using the form below:

As a frequent business traveller to the Middle East and Africa, to me the thought of mobile phones being allowed on aircraft is horrendous. I can imagine being on an eleven-hour flight to South Africa only to be woken up every five minutes by phones ringing or to hear my fellow passengers indeed shouting, "I'm on the plane".
Mike Nash, UK

Another issue that is on the horizon is the introduction of fuel cell batteries; these typically run on methanol - which is prohibited in the cabin of civilian aircraft - meaning that no one will be able to power their phones, laptops gameboys etc in a few years anyway
Chris Hoare, Leicester

I was given a hard time once for switching on a pocket-sized GPS receiver (just for the idle curiosity of checking the speed of the aircraft). I pointed out that it was simply a passive receiver of radio signals, so how could it cause interference? And besides, how would that possibly square with the fact that there was another GPS receiver operating happily in the cockpit?
Clive Tully, UK

Being a professional pilot I have had various encounters with passengers using their mobile phones. Sometimes I can hear their conversations in my headset. What is very noticeable is that when phones are ringing, there's interference in the audio circuit (a kind of annoying buzzing).
Daniel Juzi, Switzerland

The most important reason why you can't use your mobile on a plane is that the network of mobile phone cells cannot cope with a large number of mobiles moving across them so quickly. This is a much more important reason than the over-played problems about avionics interference.
Graham, UK

As an aircraft engineer, the warnings that we are given about the use of mobile phones around aircraft pertain to non- or premature operation of squibs. Squibs are pyrotechnic devices fitted to fire extinguishers which, when fired remotely, permit the fire extinguisher to reach the point of fire. These are typically used in areas where crew can not gain access, i.e. cargo holds, engines, etc.
Marcus, England

I'll be avoiding whichever airlines decide to relax these rules since they obviously have no consideration for passengers wishing to enjoy a peaceful flight.
Martin , UK

I am sick of seeing people jeopardise everyone's safety on flights by selfishly brandishing their phone around, or arguing the toss with cabin crew. What is so hard about obeying a simple safety instruction?
James Tyrell, UK, Newcastle

In my view, the banning of mobile phones whilst on air, has more to do with the fact that cell phone base stations cannot in some instances cope with the fast switching required from one base station to the other, due to the aircraft hence the mobile phone travelling at speed. The argument for interference has no solid scientific substance.
Panos , UK

Not mentioned in this article is another, lesser-known reason that mobile use is discouraged in aircraft: that handling calls from phones travelling at 600+ mph, at 20,000ft, can cause havoc to mobile phone networks. The ground antennas have limited range, which means that inflight calls have to be handed from antennae to antenna every couple of seconds, which is quite difficult
John, Netherlands

I've never had trouble playing my GameBoy Advance on the plane. I usually ask a stewardess out of courtesy. Icelandair actually offer them for loan for the duration of their flights!
Alastair, UK

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