Mobile Phones in the Cabin

[PyroTek]

I am pretty sure, almost 100% sure this question has been posted before, but i'm not going to sift through a crapload of results on the search function.

So i ask..
Why do they make you turn off your mobile phone in flight? well really, why do they make you turn off electronic devices during takeoff and landing?

I've heard some people say that theres no reason to turn off mobile phones during flight and other people say that its an interference thing..
Can somebody please go into depth as to why it is either pointless or not about mobile phones being off during flight?

dan

[Jabawocky]

Nobody knows...............just do it, that way you and the others around you can enjoy the safety briefing without a phone ringing!:ok:

[Wangja]

'Tis one of the few refuges.

Ever may it be thus.

[flog]

Here's some research info I found a while back relating to portable device incidents in AU.

http://spreadsheets.google.com/pub?key=p60h0dN2Vl8X-jcsFsCd_GA

[PyroTek]

ah that's helpful, ill have a look...
thanks a lot :D

[bentleg]

why it is either pointless or not about mobile phones being off during flight?

The radio waves from the mobile phone (even on standby) cause signals to be generated in nearby wires and in nearby antenna. Where these wires/antenna are important to an electronic device it can effect the results produced by that device. Simplest example is the noise you get in your headset when flying (which is annoying rather than harmful), to errors in display or failure of important radio aids (as flagged by Wanja).

It doesn't always happen, but it can and does happen.

[Blenk]

bentleg is on the right track, the long wires in aircraft actually act as antennas and pick us all kinds of interference that is emitted by electronics devices.

This is why all aircraft equipment's certification program now involves EMC testing for both EMC emission and susceptibility to know that it will not produce any harmful emissions and that it will not be effected by any. The problem is that these standards test over a common frequency range and to set limits expected in the outside world. They can not take into account all circumstances or all portable electronic devices on the market.

The reason that all electronic devices are switched off for takeoff/landing is that although a lot of the interference caused is non-critical (ie flickering of a screen), the pilots have enough to worry about during this phase of flight. Sometimes the interference can cause warnings etc. to be displayed, in cruise other systems can be checked to determine if the indication is plausible or likely due to sensor interference. On short final this is not so easy.

[Cap'n Arrr]

I've personally seen the VOR needle dancing in time with the DAT DA DAT from a searching mobile phone. Just leave it off, it does have an effect (although it can be shielded against most signals), and it is both safer, and a hell of a lot nicer.

Imagine flying SY --> LAX, spending the entire flight listening to someone going on about what happened last night, or the business deal theyre trying to close.:yuk:

[Wangja]

or "I'm on the plane, we're on time, clear blue sky, a few clouds, meal carp".

Jeeez, a plane is the one safe haven from the bloody things.

[HardCorePawn]

Jeeez, a plane is the one safe haven from the bloody things.

Reminds me of my first flight to Hong Kong (Kai Tak)... parked at a remote stand and had to bus to the terminal building...

Watching the hordes whip out the 'handphones' and start jabbering away the second they cleared the aircraft door and were walking down to the bus just reinforced how peaceful (despite the 4 giant donks) the previous 10 or so hours had been... :ugh:

Although getting a running commentary of my entire visit ("Yes, we're bus-ing to the terminal".... "I'm waiting to clear immigration".... "This giant white guy is holding up the queue"... "I'm waiting for my bags".... "The train should be here in 2 minutes"... "we're 3 stations away"... etc. etc.) was very helpful... might have had to actually pay attention without it :rolleyes:

[To infinity & beyond]

Imagine flying SY --> LAX, spending the entire flight listening to someone going on about what happened last night, or the business deal theyre trying to close.

I did't know they had telephone towers in the Pacific Ocean.

[WannaBeBiggles]

Great link flog! :ok:

Electromagnetic Radition / Frequencies from equipment is a big enough issue when designing a/c, let alone that produced by other electronic devices not designed to the same EMR guidelines aircraft systems are designed to.

Cap'n I have experienced the same behavior you described previously.

Plus I must say it $hits me to no end when someone leaves a mobile on and I keep getting the DAT DAT in my headphones! :suspect:

[vee tail]

What about the fact that when people are playing with thier phones, lap tops, ipods ( whether they interfear or not ) whilst taking off or landing ie, critcal stages of flight, are not paying attention for cabin announcements be it serious or not and miss something about the possibility of the s*&t hitting the fan. Ipods and headsets to lap tops can be pretty loud. Duty of Care should be a consideration......:ok:

Just a constructive thought.

[Jabawocky]

I have proven they interfere with the Transponder in my plane.

That incident list was interesting......not one mention of the scAirbus at all:eek:. Maybe with all the computer control they are better shielded? Who Knows:confused:

Just turn em off....all of them!

J

[ules]

this has got to be a load of crap

24-Sep-04 200403855 Makin, (IFR) WA B 737-7BX Laptop Unknown INAV & VNAV disengaged, FMA enuciated LWS R & ALT hold with AIP P/RST caution flashing. AIP B remained on. Autopiliot Yes. Pax playing DVD on laptop

laptos cannot really interfere with communications or anything, unless wireless or something is enabled. and the signal will only really interfere if it is near the cockpit,

sorrry tought playing a dvd will not have effect on any aircraft, its just propoganda crap

[WannaBeBiggles]

Wireless or bluetooth might have been enabled and remember that clock frequencies of things such as that of the system bus and the cpu do produce electromagnetic fields.

Now if the said frequency come close to any nav equipment and the associated wiring then the possibility does exist that the equipment can interfere with aircraft equipment.

Not sure if someone knows the case study, but I remember seeing a reference to a case study done on electronic interference on the F111 in the mid 80's... not sure if the doc is in the public eye (can't see why not) as I saw this while working for a defence contractor.

[flog]

It all becomes interesting when CASA start trying to put an approval process around electronic flight bags that are not rated to specific aircraft.

What happens when I buy an eFlyBook from the US and try and run it up from the left seat of the Saab340 I'm currently in to see the approach plates and use them through to land...

[Cap'n Arrr]

Another interesting thing I found out driving home today (Please don't ask how I found this out, I was bored:E)

Try tuning your radio to a very low AM frequency, where there is only static, no station. Turn it up a bit and drive around. Hear the pitch of the static change with your engine RPM. Try turning on your lights, wipers etc, and hear the interference in the otherwise clean static. Reach out and put your hand near the aerial. The fact that these things change the sound of the static is proof enough for me that nearly all electronics make EM fields which can and are transmitted through wires in various forms, whether it is to make a noise of dit di dit, or to give the autopilot the 5000'/min RoD command. (No my car doesn't have autopilot, so I can't prove that one:E)

I think the other people forget is that airliners have wires running down the whole length, it's not like all the electronics are isolated in the pointy end, so when you put the laptop near the wall, it could (for all you know) be an inch away from the elevator servo wires.:eek:

[WannaBeBiggles]

Cap'n, I have experienced that same when I have my Bearcat frequency scanner on and the airconditioning compressor kicks in, or when wipers are turned on :8

[ules]

hmm you do have some strong points there..
but seriously a laptop.. cant meerly have that much power to interfere with such high electronics of a large aircraft.

if a laptop can interfere with a large aircrafts equipment. why not our equipment, our hearts ,, brain,, give us cancer ., or something .
if a laptop did produce that much electronic interference ,, why doesnt it interfere with its own parts,,
laptop comes in diff bits, diff voltages, etc,different parts,,
cpu , cd rom, ram , gfx card, other ports, see they all run of the same fine, why dont each part clash with eachother.

i dunno guys but i find it really hard to believe a laptop to really interfere that bad with a large aircraft, such as auto pilots and other nav equip.

i think the reason why they mainly ask to pack up everything at take off and ladings, is to back up their own ass. as into safety, so no laptops or phones go flying around the cabin hittin someone in the head and then them sewin the airlines,

:}:}

[QSK?]

This link might help, at least with mobile phones

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

[Cap'n Arrr]

What you're forgetting, ules, is that a large aircraft is essentially an assembly of a sh**load of very small parts. You may or may not be aware, but the servo tab I was talking about is used on airliners, and it is a sort of reverse trim tab (the servo tab is deflected by the controls, not the elevator, and the airflow over the tab causes the elevator to move in the desired direction). On Fly By Wire aircraft (e.g. the A380) that tab is controlled by electric impulses sent in much the same way as how you moving your mouse causes the cursor on the screen to move. Sure, it's technologically advanced, but a mouse doesn't require a nuclear plant to power it, neither do many jet systems.

I guess the point I'm trying to make is that it only takes the laptop to interfere in the right way with one tiny system, and send one tiny, erroneous signal that was not commanded by the flight or cabin crew. This may be a dat da dat sound over the radio, or changing the 7th waypoint in the FMS from Melbourne to Moscow. Granted, it is unlikely, but it is also entirely possible, so in my opinion, just listen to the cabin crew.:ok:

Another interesting story, I used to have a toy fire truck (back in the day:E) which had all the flashy lights and sounds, and a good close lightning strike would set it off.

[PyroTek]

Like many enthusiasts, such as the ones on FlightLevel350. I like to video takeoffs and landings etc. while flying.. what effect would this have, if any?

I mean, many many people do that. and Its up to the discretion of the flight attendants to allow it or not, but what are your views?