Cell phones in airliners

[james ozzie]

This may be an old topic but here goes...

Some years ago as a passenger into Johannesburg in an SAA Airbus (before the Boeings..before the Airbi) we were doing the taxi from Boksburg to Kempton Park & the passengers were repeatedly firing up their phones despite requests not to. Eventually the Captain came on the intercom & warned that the use of the phones could interfere with the planes braking system & cause us to come to a dead halt with locked wheels.

Could he have been spinning a story there? If it were really so then NO cell phones should be allowed in the cabin at all because of the potential for a disaster on take off?

I assume the major risk is interference with comms signals - what about nav signals? What is the present state of knowlege on this subject?

[forssi]

I've asked the same question before, and what i've been told that it affects the ILS system on board, correct me if i'm wrong...

[B Sousa]

Not being an electronic wizard, I will just have to defer to those who make the rules and say, Yes its a possibility it will interefer with navigation.......
However in the real world on non airliners folks use them all the time and survive.
One thing I feel caused the problems was the phone companies themselves. Cell phones were designed for line of sight. So when you turn on a cell at an unusual altitude it hits more than one site, thus creating confusion within the phone system....Who knows it may even cost them more money.....Wouldnt that be a shame.
Maybe someone like Rhodie could jump in and explain. He worked with this stuff for a while......

[contraxdog]

What the captain most probably meant was that, if he hears another bidi-bidi, in his head set, he will stripp his moer(nut) and stand on the brakes out of fustration, untill the F/O has found the perpetrator, and threw him out of the aircraft.
I can see THAT happening!

[barryt]

contraxdog:

I think you are absolutely correct, and was about to say the same thing.

[SebasW]

I seriously doubt that a cell phone would cause something to go majorly wrong in a plane.

The magnetic fields in and around a cellphone can however affect the compass but you have to be in quite close range to it. Put a cellphone close to the compass and see what happens, just don't tell the engineers that you did it!
;)

Apart from that I don't think it has much affect, but just think about it... If you fly the new A380 and you've got how many hundred souls in the back chatting away on the cellphones, it's gonna sound like you're listening to morse code on the radio and it's gonna annoy the living hell out of us pilots!

I have also heard that using a cellphone that high up, if you actually get a signal, you bugger up the signal for the users on the ground, don't know how true it is though...

[Rhodie]

Technical knowledge is a bit rusty - been out the business for a couple of years.. but to answer the question, a cell phone can interfere with avionics.

The wattage output is not so much the problem, but the signal being sent out from the cellphone 'looking' for a receive signal is. This signal will pulse sensitive electronics and create a disturbance ( flux) in any close proximity wiring - this is what leads to the waving needles and screens on cathode displays. It can be distracting, but worse case is that it can lead to a (LCD) display freeze (last known page scenario). Not that common on big aircraft, but I have seen it on a small business turbo-prop where a cellphone was in a bag in the closet behind the crew, right against the wall - the interference was not only on the TX, but was visible on the panel as well.

Bert and Sebas are also right in that a cellphone is designed to use a single 'cell'. It can and will cross-over in different areas, and can be carried on more than one channel on more than one base station - but - when line of sight is now a good few thousand feet up, the signal will be interogated by numerous cells and depending on antenna direction will tie up many channels while searching for the strongest signal. Cross-over is not the issue, as this happens in town and country driving all the time, but is limited in direction. A 'high density' site, as in Sandton City building (for example) may have 27 micro sites around the building - hand-over is taking place all the time depending on availability and signal strength.

Brings to mind the old story where a vehicle tracking company, using cell tracking, clocked a stolen vehicle at 600 kph...! Turn's out the car was already loaded on a freight plane and airborne..!
Not sure how true, as the aircraft height and shielding may have prevented signal, but the story's a good one.. :ok:

A cellphone has saved my but while flying tho' - complete electrical failure in a C210, at night, and, of course all Maglite batteries dead, the phone was first used for panel lighting (push any button every 30/40 seconds to turn the light back on) and then to phone the tower 1/2 an hour out..

I also used it once many years back to call Eros tower (Whk) after a mike failure in a little C152.

I see that the US stores now sell a cell-phone to headset converter, so calls can be made and received while flying - for small planes maybe, but not for big and fast.. I don't think it's legal here in sunny SA tho' - will check..

Cheers

R

[REAL ORCA]

Tried a cell phone many times during the cruise-it does not work! There is just no signal. Not completely convinced it can have an adverse effect, but have to abide by SACAA rules!!

[Kapt. Ive]

Confession: In 1995, I fired up my mobile on the flight deck one morning. Simultaneously, the FMS popped some of it's circuitry. Two hour delay !!! A few days later, thinking that it was a mere coincidence of timing, I repeated the incident in it's entirety.

No, that's NOT what I wrote in the techlog...

:ouch:

[wheels up]

Which reminds me of a rather embarrasing moment...

Co-pilot was busy briefing pax which included stern warning that all cell phones should be turned off. Just at that moment my cell phone, which was in my overnight kit in the rear of the aircraft, and on, started to ring.

Co-pilot proceeded to answer phone, walked to front of aircraft, handed me the phone and said "Its for you!"

[I.R.PIRATE]

When a cell-phone starts its irritating little morse number in my ear, my co-pilots efis screens flicker in time with it, so I am a firm believer that there is definitely some interferance caused by phones in the cockpit. And yes, it certainly does cause the brakes to lock, and for some or other weird reason, it causes my co-pilot to get up and return to the cockpit with a handfull of phones.:}

[SebasW]

That's where flying cargo has it's advantages:

-They tend not to have cellphones and they never complain.

The downside however is that the people that put the cargo on the plane generally complain more than any passenger could ever complain! :\

[Beta Light]

On the older 707's with 1st generation Anti -skid the H.F. had to be switch of until 10000ft and again on decent as some of the H.F.freq / selcall interfered with the anti skid - releasing the anti skid if memory serves me right but will have to check with the f/e 's