View Full Version : Mobile Telephones in Aircraft

Stefan Stefanovic
16th Oct 2003, 21:50
Since Mobile Phones have been interduced. Airlines have banned them on being ON. But as i have found out that some airlines do not let mobile phones on in the aircraft at all. While some other Airlines let them be ON while the aircraft is on its final parking place at the airport.

So it seems some airlines let theire passengers to use theire mobile phones on the aircraft when its turned its Engines off

can any body help me on the issue

16th Oct 2003, 22:04
mobile phones don't work above a cpl of thousand feet so they might as well be off.

16th Oct 2003, 22:22
The regulations (what there are of them) regarding the use of mobile phones is a bit mixed up to say the least.
I.E. It is the CAA etc that object to their use on or near the ground (interfere with ILS Etc) but it is the phone companies themselves that object to there use in the air.
Can you imagine the poor little GSM network trying to hand over 300 mobile phones going from cell to cell at over 500 mph? The network would crash!

As was stated earlier, there are no real regulations and only guidelines which can vary from company to company and country to country. Probably from aircraft to aircraft too when you think of the implications in a fly by wire environment.

Don't know about 1000 feet limit. I would say that I can use my phone more than 1000 feet from a cell so I would say that was a load of *****!

16th Oct 2003, 22:27
Never heard of mobile phones being physically banned from an airline. Can you imagine the rigamorole (sp?) of searching every passenger? Probably 80% + of passengers take a phone onto a plane.

Incidentally, I was flying between Texas and Illinois once when a lady tried to phone back to Texas to see if the rest of her party had made the next flight. Apparently she couldn't get a signal... :rolleyes:

16th Oct 2003, 22:37

but it is the phone companies themselves that object to there use in the air.
Can you imagine the poor little GSM network trying to hand over 300 mobile phones going from cell to cell at over 500 mph? The network would crash!

The primary problem with airborne mobiles is that they can be seen on non adjacent cells on the same frequency simultaneously. This makes the network call routing problematic.

16th Oct 2003, 22:42
Here in the US, mobiles can be used until the main door is closed ... and the FAA have just introduced a new relaxation that they can be used right after landing when the aircraft is taxiing. Not sure if all the airlines have implemented this, but Continental announce it once off the runway.

The actual rules (part 91) the FAA lay down is that no electronic devices can be used on an aircraft operated by a air carrier / commercial operator or on a civil aircraft on an IFR flight plan. I guess there must be another exception for game boys or something.

As far as the effective height for cell phone use ... errrrr, text messaging works ok up to about 7000 feet though voice doesn't, so I am ... assured ;) Wasn't me, honest guv !!!

Golf Charlie Charlie
16th Oct 2003, 23:01
mobile phones don't work above a cpl of thousand feet so they might as well be off.

They clearly worked on 11 September 2001.

16th Oct 2003, 23:08
Not if you're a conspiracy theorist...

17th Oct 2003, 01:45
In Canada cell phones certainly work at all altitudes as it's the same system I am sure this is the case anywhere.

As others have said it's the phone companies themselves that have the greatest problem with airborne use. As far as interference with a/c systems I think the verdict is still out. There is a system available in the USA aimed at the corporate aircraft world called Aircell. It ties into the existing cell network while on the ground but the difference is that airborne it only hits a limited number of cells so as to not flood the system. I presume it's the same frequency spectrum so I am not sure where that leaves the whole interference thing?

Bob Brown
17th Oct 2003, 02:06
A few months ago, Mrs BB acidentally left her phone on in her bag when we flew from Gatwick to Dalaman.
Got the phone out when we arrived at the hotel and had several txt mesages from the various countries service providers welcoming us etc. The do work some of the time at least.

17th Oct 2003, 02:31
posted 16th October 2003 13:04 ___ _ _ __ _

"mobile phones don't work above a cpl of thousand feet so they might as well be off"

So no one in the Alps or any mountain area can use mobile phones? Don't think you are quite correct there. Didn't realise a mobile phone has a built in altimeter cut-off switch! Or an earth proximity switch!
The power transmitted is so low that I would be surprised if any transponder belting out around 250 watts or any aircraft electronic equipment would be affected.
Another urban myth maybe.

Aviate 1138

17th Oct 2003, 02:42
I'm just saddened that people can't be without their telephone for such short periods.

Do these people sleep with them as well?

17th Oct 2003, 03:01
OK definitive, mobile phones work at altitude (about the same as they work at most lateral distances from base stations.
The biggest risk in the air (but the vote is not out yet as has already been stated) is from the phone registering with cells and networks (that's the characteristic chattering sound you hear on nearby equipment) which is at a higher power than normal calls and messages.

There are a couple of companies out there who are working on making cell phone technology available on board as the airlines would love to be able to do away with the weight of their fixed onboard phones (and save loads of dosh in fuel savings). Since everyone takes their own phones on board anyway.
The system I am aware of would place a very small cell in each aircraft so that phones would register once and then since it is 'captured' the airline can charge the calls at the usual US$12 per minute.

There are some technicalities to work out, not to mention the approval by various authorities.

chocolate bob
17th Oct 2003, 03:09
I agree with flaps one. Why some people just go without them for the period of a flight beats me.

All countries should do as they do in Germany, that all phones are switched off as soon as the pax board the a/c and not allowed to be turned back on until they disembark

This would solve any differences and it should be made an offence to break the rule.


17th Oct 2003, 03:13
I never believed the interference excuse. But on the current aircraft I fly I can hear the static over my headset if my FO forgets to turn his phone off and he gets a phone call.

17th Oct 2003, 04:44
I couldn't use my cd player on a flight from london to mauritius (air mauritius A340-300) a few months ago! Now i dont understand why those in first class can use there laptops complete with a power point to plug them in (most come with a cd drive) when i cannot use my cd player in economy! where is the sense in that??? and why didnt the other flight attentants say anything to me even though they clearly saw it or was this guy just fussy?? i understand cd players or laptops cant be used during take off and landing.
however on the return flight (British Airways 747-400) i was allowed to use my cd player (was in world traveller plus and not economy so wondering if that might have had a part to play!!) :\

On the mobile phone issue. We were only allowed to switch our phones on once engines were off.


17th Oct 2003, 05:07
The primary problem with airborne mobiles is that they can be seen on non adjacent cells on the same frequency simultaneously. This makes the network call routing problematic.

I am not sure thats quote true. GSM phones are always seen by > 1 cell at a time, however the phone itself decides which one to work at any one time. Equally, the frequency is not an issue. A mobile phone divides its calls on timeslicing as much as anything (TDMA for GSM and CDMA for 3G). I am gonna check the real reason with a mate who is a network engineer fir a GSM operator

17th Oct 2003, 05:36
Do these people sleep with them as well?

Only if its switched to vibrate.....:}

17th Oct 2003, 05:59
Here in the US, mobiles can be used until the main door is closed ... and the FAA have just introduced a new relaxation that they can be used right after landing when the aircraft is taxiing. Not sure if all the airlines have implemented this, but Continental announce it once off the runway.

Southwest airlines has implemented the after landing use of phones policy. Folks LUV it as they can call for their rides, pickups or let the family know what time to expect them.

As for the interference of cell phones (or other transmitting devices) with aircraft systems, the issue is still cloudy. There appears to have been anecdotal stories of ILS anomalies traced directly to use of cell phones in the cabin. Yes they don't transmit much power or at the exact frequencies as our systems are set up to receive but they are a lot closer to the antennae as well as being close to wiring routed nearby.
Since we can't certify every single transmission device at all seat positions and combinations the prudent thing for the FAA etc to do is just ban them.

Let the debate rage.

17th Oct 2003, 06:14
Zaptin is this the system you have heard of or another one?


It was announced this week at ITU Telecom.

17th Oct 2003, 07:41
The relaxing of the taxi-in rule in the US was the result of a very long extensive study by American Airlines' Tulsa Tech unit and the FAA. No aircraft interference could be reproduced, blah blah...so hence the new situation.

As the SWA poster put it earlier, people love it. I actually think it can substantially reduce congestion outside Arrivals at the terminal, as Limos etc, can wait off-base and drive with perfect timing for a pick-up as the plane taxis in.

17th Oct 2003, 16:40
My boss is both an aerospace EMC engineer with many years of experience and mobile phone junkie but has absolutely no time for mobile users in aircraft. She has been known to tell off fellow passengers who try to use them.

FlapsOne: I manage to do without one all the time.

Faire d'income
17th Oct 2003, 19:51
I am not a mobile phone engineer but I am aware that the
antennae they use only have a limited angle of sweep. The angle of tilt ( something like a wx radar ) determines where a signal is available. It would seem obvious that in the UK which doesn't have any high mountains that the angle of tilt would be always very low particularly in densely populated areas.

Also in Europe where each country has licensing rights for moblile companies a higher tilt angle would result in signals crossing borders more often ( it is a problem as it is ) avoiding roaming charges or getting unwarranted roaming charges.

A combination of the above might explain why in NW Europe you don't get a signal above 1000' and also why in the USA it is possible .

17th Oct 2003, 20:18
I had just heard that because as the phone gains height it gets line-of-sight for multiple cells of the network, and this causes lots of problems so that in the end the phone provider will disconnect the phone.

I've taken my mobile glidng loads of times and it will work fine up to maybe 2000ft but after that the signal just goes.

Dave Gittins
17th Oct 2003, 21:17
I think we have run to ground that phones do work in the air - at least up to 2 or 3 thou. I can't speak about higher than that but 9/11 certainly indicates that they do as do Mrs BB's welcome messages across every country between Gatwick and Dalaman.

They also "roam" when near borders. On one Turkish trip, I got loads of messages welcoming me to Greece.

Personally I am at the beck and call of the damn thing all day and a good excuse like, I was on an aeroplane, suits me fine until I am in the terminal.

I can also attest to them interfering with aircraft equipment - at least transponders. I have occasionally forgotten to turn off the phone in my shirt pocket and on one particular occasion It blocked my transponder signal, as Luton were quick to tell me. They said they had lost my squawk (whilst I was about 2 miles away and 1500 ft), just as I heard the characteristic "chatter" of the phone in my headset. I switched the phone off, told Luton I had recycled the transponder, and they confirmed that it had just come back again.

I try and pay more attention now and it is a final check pre take off announcement to my pax - Can you please check that you've turned your phones off ???.

I would expect more safety critical systems - like the FBW to be more robust to RF intereference - FM immune indeed !!

In the past, I have found phones to interfere with all manner of electrical equipment that isn't too RF immune. The "chatter" that affects TVs, my clock radio, landline phones etc. has a hell of an effect on other things, I used to have a major effect on on-line analytical equipment in water treatment plants in a previous life and sent the dosing pumps haywire.

Have heard that easyJet's checklists have mobiles off - on the pre-take off ..... and mobiles on - on the after landing.


Pax Vobiscum
17th Oct 2003, 22:35
I'd be happy to bet that any flight with more than (say) 100 pax will have at least one (probably several) active mobiles on board - whether due to ignorance, carelessness, bloody-mindedness or whatever. Since, thankfully, we don't observe flights dropping out of the sky, I assume that any risks from the operation of such devices are minimal.

I'm all in favour of minimising the (already miniscule) risk of commercial flight, but in the real world where (it seems as though) almost everyone over the age of 7 has a mobile, you can't eliminate the possibility that one will be operating inadvertently.

18th Oct 2003, 00:15
If mobile phones are capable of posing such a serious threat to the safety of an aircraft, why do terrorists insist on trying to smuggle explosives on board???

18th Oct 2003, 07:38
The phone ban is a sensible precaution due to the miriad of avionic equipment in use and age spread.

Remember that not all avionics of the same class are born equal. Early equipment would not have endured the necessary EMC testing at the mobile/celular frequencies in use today. Also consider that the EMC issue isnt just pick up from antenna and receiver front ends, but also through wiring looms.

The same is true for the ban in hospitals, although I loose the logic there when you see mobile phone antenna on the roof of a hospital!

Personally I believe mobiles should be banned from public places full stop!! hehehe

18th Oct 2003, 11:16
Not long ago I was deadheading on WN from KLAS to KRNO. After takeoff the fellow sitting across the aisle started his laptop and called up a webpage! I then noticed a cell card in his pcmcia slot, blinking merrily. He did lose signal rather quickly, but that is pretty normal as the area between KLAS and KRNO is desolate and cell phones do not work well even on the ground. This incident has made me rethink the cell phone policies, as how do we define what is a cell phone and what is not. All sorts of devices are out there which use cell phone technology, but bear no resemblence to a "cell phone".

21st Oct 2003, 03:44
About a year ago i was watching an inquest into the RAF CH-47 that crashed into the Mull-of-Kintyre in Scotland and they mentioned the possibily of a mobile phone signal being a contributing factor. It was stated that in the UK only mobile phones connected the the Orange network could interfere with the avionics on board due to the frequency being used by that network. I don't know what frequencies are used or if things have changed since the accident but if it was brought up in an offical investigation then i must believe that there is some truth to it.
On a slightly different note egnm has just banned the use of mobile phones until pax are inside the main terminal building. They have deemed that people using a mobile are not paying full attention to their surroundings and so are a health and safety hazard to themselves and others. I wonder haw many other airports will follow suit?

21st Oct 2003, 04:01
Sounds like someone had something against Orange. Actually, all of the mobile networks use the same range of frequencies. That's why, if you try, you can attempt to log into other network providers with your phone. They then validate it throw you out if they don't like you.:)

21st Oct 2003, 23:53
sony ericcson P800 and Treo , and of course O2 XDA have an inbuilt phone. so a pax seemingly playing nintendo could be text messaging somebody if there is a connection.

my five cents worth, Fl 310, on a direct to KLARK, a pax h/p was still logged on AT & T wireless.

22nd Oct 2003, 00:29
If you think that interference from cellphones is bad, you should see what plod radios do to my TV!

I think the record I've had for 'networks available' at ground level was around 9 or 10 in Friedrichshafen - some German, some Swiss and some Austrian..... But the phone didn't get too confused!

The way forward must be approved 801.11b or g W-LAN systems in aircraft linked to the Internet. Then people could e-mail their contacts - SILENTLY!! None of this "Yeah, 'ello Jim, it's Ray. I've been to see Alec and the buyer says..zz..zz.." which you get in loud voices in most trains these days. SHUT UP you rude $ods - go and stand in the carriage entrance if you must use your spiv phone in the train!

Self Loading Freight
25th Oct 2003, 21:44

I think the real answer is coming down the line - ultrawideband, or UWB. The standard's still cooking -- 802.15.3a -- but it promises to provide hundreds of megabits a second over wireless. The really good thing is that it's ultra low power: the FCC approval for the system states that the transmitters aren't allowed to emit any more power than ordinary electronic equipment without transmitters radiate anyway. So you shouldn't be able to tell the difference between a laptop with no radio and one using UWB. On any particular frequency, it just looks like a very low level noise source.

Not that people haven't been worried -- UWB transmits on all bands simultaneously (arm wave, arm wave), and there have been worries that enough of these things in a small place could significantly raise the noise floor on the GPS frequencies. Tests so far seem to be fine, and the standard will most certainly be immune to one of the more dangerous forms of interference where a signal is picked up by a piece of equipment, rectified and turned into DC that then messes up normal functioning. There's just not enough power there to do that.

The downside to UWB is that it's low range - ten metres max. However, that's probably an advantage in an aircraft, where you can have UWB gateways in each seatback (or row of seats) and get very high densities of usage with very low overall power levels.