Mobile Phones

[rockon tommy]

Can anybody name the systems or equipment on airliners that are affected by the mobile phone and demonstrate that effect on the ground and in the air.
I have heard from the 'What if army' and the 'Better save than sorry brigade',the guy who new a guy who operated a discharge valve with his mobile, and the'I cocked up the approach and landing but it was not my fault as a mobile, laptop. elec toothbrush etc' was in use in 16c.
But never any facts.
Regards to all. Rock on. Tommy :)

[Willie Eckerslike]

It is very difficult to say for sure that any incident has been caused by mobile phones or laptops. However we have all heard the back ground noise over the RT as mobile phones interfere with transmissions. I also know someone who lost the entire content of the FMC database during flight. Shortly afterwards a passenger was found reprogramming his mobile phone directory.

The simple answer is that mobiles could interfere. Just because a young child is playing with matches doesn't meen he will get burnt but he could! Would tou let your child?

[captain]

Try to hold your operating mobile phone close to this PC monitor and see what happens.
Incidently, also aircraft systems may interfere: operating the electric hydraulic pump on a F-100 will cause the (electric) tap of the rear toilets to run spontaneously; when switching on the Logo lights on a B763 will cause the CVR test light to illuminate momentarilly.
Go figure, but switch those mobiles off please!!!!!
SJ

[fen boy]

The CAA has actually scientifically proved that mobile phones interfere with aircraft systems and instrumentation. I beleive they are planning some further research to test with specific bits of kit.

[Rotorbike]

But then again after much trouble using a radio frequency, we rigged up a mobile phone to a headset for traffic reporting in a helicopter.

No bleed to the radio.

Will admit a Bell 206 isn't all singing and dancing glass cockpit.

:eek: :eek:

[criticalmass]

It depends on the type of transmissions from the mobile phone. The packetised transmissions from GSM mobiles are especially troublesome because they are reputed(!) to have a similar structure to messages sent by FBW control computers and their peak power is relatively high. These are the mobiles that are frequently heard "burping" in audio gear etc. The whole GSM mobile thing is, in my opinion, a real pain!

Analogue mobiles radiate less power and there is no packetised structure whilst the CDMA phones have different transmitter characteristics to GSM and don't "get into" electronic gear nearly as badly even though they are also digital transmissions.

FWIW I will be abandoning the kludgy, bug-infested Australian GSM mobile network soon and going totally CDMA. But I still won't be turning my CDMA on in any aircraft. Apart from anything else, a mobile aloft can totally confuse several cell-sites and cause problems for multiple users.

For some odd reason the mobile phone manufacturers are a little coy about these problems...does that remind you of the tobacco industry? I work with radio waves all the time and I'm convinced they will become the asbestos of the 21st century.

[Pointer]

On the Fokker50 a mobilephone can trip the 'auto elevator feel control' this relates directly to the flight controls and therefore is a very big NO NO ! and yes i've had it happen on my flight. It takes a maintance reset and if not possible to reset there is a maintance procedure to disconect it and whe'll have to climb in the books to find the penalty in weight and CG loading.

Many times people hev had theire phone on and are playing games on the D@#%#$mnd things, and after being 'asked' to switch it of, saying things like;"the phone is not on, i'm just playing a game". When they are reluctant to switch it off, i'll make a PA like;" i hope every body likes to end up in our destination"

so yes it has a profound effect !

[radeng]

There's two factors to consider: one is the field strength produced by the phone, and the other is the immunity level of the a/c equipemnt.

A GSM phone producing 1 watt gives about 3 volts/metre field strength at 1.8 metres distance. Power control in the system reduces the transmitted power in areas of strong received signal, so the 1 watt doesn't get used that often. Incidentally, the average power is a maximum of 1/8 of a watt - not enough to properly light a torch bulb. Going out in the sun on a mediterranean beach puts you in a power density of 1140 watts/sq metre, which would be 650volts/metre. The microwave safety limit is 50 watts/ sq. metre.

The international level for immunity for 'light industrial and domestic premises' is 3 volts/metre, except for conventional telephones and domestic radio, TV, hi - fi and the like. Within the EU, any equipment sold after 1996 should meet these immunity levels. For safety of life equipment, such as maritime radio comms equipment, the level is 10 volts/metre.

Many aircraft equipments are of such age that they have little immunity, and the only way to make sure is to switch off the interferer. This is akin to saying 'my roof leaks, so you have to stop it raining', and begs the question of the inherent safety of the aircraft systems.

No one has yet explained to me how the big radars, such as the 25cm wavelength one at Heathrow, (over 1000 MWatts)don't screw up the aircraft systems, while the 1 watt GSM does - the field strengths of the GSM at 1metre are equalled by the Heathrow radar at 31 kilometres! The attenuation of the a/c fuselage isn't that great, because of the holes in it for windows.

A report to CEPT (the European conference on post and telecomms) the otehr year suggested that it will probably be about 2015 before airliners will all have equipment that is insusceptible to electromagnetic fields of 20volts./metre, and so there are recommendations on limiting the use of electronic news gathering equipment near airports - they can radiate appreciable powers at about 2.4GHz.

It has been suggested that there can still be a problem on aircraft, because it's hard to ensure that cables in the wiring looms don't chafe and lose their screening effectiveness, thus compromising the system immunity. Corrosion can cause discontinuities which are also very harrd to find.

Because of the effectively intermittent nature of some of these problems - the radio has to be transmitting in the correct time slot to interfere with the FMC or whatever at the same time as the FMC is doing something that can be interfered with - tracing the exact problem isn't easy. It could well take 40 or 50 hours of flying, and trying every possible manoeuvre while using the phone in every possible mode. Even then, there's a good chance you could miss something.

Incidentally, it's been claimed that a number of RAF Tornadoes have crashed because they got to close to high power broadcast transmitters....

But those big radars still slightly worry me in their possible effects.....

[CCAero]

Even if they didn't interfere with aircraft systems, can you imagine 14 hours of non-stop ringing mobiles and text message bleeps. I say ban 'em anyway!!