Cell Phone Blocking.

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gnfb

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#129440 16-Sep-2013 10:46

I was just reading an article regarding the never ending question/argument regarding cell phones interfering with navigation etc on planes. The comment I use to make that "If the safety on a plane was reliant on the honesty of the chap seated in 21b turning his cell phone off and not sticking it in his pocket on,then heaven help us"
I use to work for an airline ,on the ground, but was still dragged into the argument. When passengers would still be talking on there cell as they were about to cross the tarmac to board there flight and I had to stop them telling them they were not allowed to procede until they "told me" the phone was off.

Well I have a question for the clever ones amongst us. They can make devices that "jam" cell phones making it impossible to receive and send calls. I know they are not expensive as this company sells them Phone Jammers.

So why do the airlines not use them wouldn't that solve all the problems?

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#896229 16-Sep-2013 10:48

My gut tells me that phone jamers would cause even more so called interference with plane electronics.

johnr

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#896233 16-Sep-2013 10:54

The jammer works on the same band as the cell phones and puts out more interference than a cell phone, This is why the phone is jammed from talking to the mobile network,

A jammer is far worse!

sbiddle

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#896235 16-Sep-2013 10:55

Umm.. Because it's doing exactly the opposite of what you're wanting to achieve maybe?

The reason for banning phones is RF transmissions within the aircraft interfering with plans systems. How would running a RF jammer which simply emits wideband RF noise to block cellphones actually fix anything? It would merely be making the situation far worse.

PaulBags

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#896435 16-Sep-2013 17:44

What, specifically, are cellphones supposed to mess with? Would it somehow take out avionics? Mess with the autopilot? Could it interfere with communications? Slightly drown out or distort identity beacons?

Either there is a specific concern, and people should be somewhat concerned that their fellow passengers will interfere with flight systems; or it's a baseless assumption and should be challenged.

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#896464 16-Sep-2013 18:19

I concur that if they were as dangerous as they allude, we'd be required to hand them in and get them back when we landed.

They take your wife's nail file but leave you with something that can allegedly cause havoc with the plane's flight control systems?

Sure......

johnr

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#896469 16-Sep-2013 18:23

Think about it this way, All the phones are left on during take off / landing / cruising

All the handsets combined together not just 1 handset looking for signal from a cell site could cause issues

Handsets also change power output when they have a weak signal so plane climbing and all these handsets going I have to increase power output to talk to a cell tower

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GregV

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#896479 16-Sep-2013 18:28

Some older planes have less sheilding on control wires running through/above the cabin. Active cellphones in certain areas of these planes have been shown to produce interference. Can't remember where I read this, but I'm pretty sure that was the reason.

Another possible reason given (and I'm certainly no expert on this) was the multiple cell-towers a device could 'see' while airborne, and the impact that would have on the visible cell-towers (switching/hopping between multiple towers). SO not safety-related, but one that would *perhaps* cause issues for cell providers. EDIT - I see an expert replied while I was composing this

I'm all for allowing cellphones for data/sms (on silent). Couldn't stand the thought of someone next to me talking loudly throughout the entire flight though.

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#896484 16-Sep-2013 18:31

johnr: Think about it this way, All the phones are left on during take off / landing / cruising

All the handsets combined together not just 1 handset looking for signal from a cell site could cause issues

Handsets also change power output when they have a weak signal so plane climbing and all these handsets going I have to increase power output to talk to a cell tower

That may well be the case - I do not say it is not.

Merely that there is not even a shred of logic for saying "give me your bottle of water and your nail file, you potential terrorist!" but then saying "sure, keep your cell phone that could crash the plane and kill us all! No problem! Just please make sure it's off, eh?"

Klipspringer

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#896493 16-Sep-2013 18:55

Cellphones left on while traveling on a plane probably cause more chaos on the mobile network than to the plane itself.
Imagine how many times a phone will be switching bases stations at low altitude and when travelling at speed. Who knows if they will actually work at 30 000feet? The signal from a base station can surely reach that height? Probably not? Maybe JohnR can comment?

Anyhow. I read somewhere that Air NZ pilots are now using ipads

sbiddle

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#896512 16-Sep-2013 19:34

At the end of the day it's about risk. RF interference has been shown to cause issues on older aircraft and aso with the introduction of cellphones they were banned on planes.

This clearly doesn't mean a cellphone will cause interference to a modern plane - the fact thousands on planes flying around the world with WiFi gear and picocells for mobile onboard show that it can now be used with the risk minimised.

A phone however can cause issues for a network, not to mention the fact your coverage at 33000ft between Wellington and Auckland is pretty limited - cellphone antennas are sectorised panels that point down. They don't point up at the Sky. Telecom coverage from a phone is typically better than Vodafone because they still have a lot of older omni sites around in rural areas that were never sectorised.

You then have the issue of WCDMA and LTE technology and speed limitations..

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#896535 16-Sep-2013 20:08

sbiddle: At the end of the day it's about risk. RF interference has been shown to cause issues on older aircraft and aso with the introduction of cellphones they were banned on planes.

This clearly doesn't mean a cellphone will cause interference to a modern plane - the fact thousands on planes flying around the world with WiFi gear and picocells for mobile onboard show that it can now be used with the risk minimised.

A phone however can cause issues for a network, not to mention the fact your coverage at 33000ft between Wellington and Auckland is pretty limited - cellphone antennas are sectorised panels that point down. They don't point up at the Sky. Telecom coverage from a phone is typically better than Vodafone because they still have a lot of older omni sites around in rural areas that were never sectorised.

You then have the issue of WCDMA and LTE technology and speed limitations..

I agree. But if the risk is genuine, why are phones even allowed on planes?

Guns are not allowed in carry on - they have to be checked in. Nail files ditto.

So why not cellphones?

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johnr

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#896536 16-Sep-2013 20:13

When did someone last take over a plane with a cell phone?

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#896583 16-Sep-2013 20:58

Source: Boeing Engineer

The 'interference' from electronic devices was never scientifically proven to exist in the first place (only an untested theory) and pilots routinely use iPads and cellular phones on the flight deck: flight mode or not. At the very best the FAA can only say that electronic devices 'may' cause interference.

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#896597 16-Sep-2013 21:52

I take an alternative view. If a plane is sufficiently susceptible to RF that mobile phones are a risk then that plane should not be allowed to fly.

A number of years ago most UK hospitals had signs stating that mobiles were not to be used within 10 feet of the hospital building. Again if it is life an death equipment then it should be sufficiently shielded to cope with errant RF.

I have one old phone that would occasionally turn on mid flight due to a knock or bump and pick up txt messages while flying domestically. There is plenty of random RF around regardless of cellphone use.

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MaxLV

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#896656 16-Sep-2013 23:56

Geektastic:
sbiddle: At the end of the day it's about risk. RF interference has been shown to cause issues on older aircraft and aso with the introduction of cellphones they were banned on planes.

This clearly doesn't mean a cellphone will cause interference to a modern plane - the fact thousands on planes flying around the world with WiFi gear and picocells for mobile onboard show that it can now be used with the risk minimised.

A phone however can cause issues for a network, not to mention the fact your coverage at 33000ft between Wellington and Auckland is pretty limited - cellphone antennas are sectorised panels that point down. They don't point up at the Sky. Telecom coverage from a phone is typically better than Vodafone because they still have a lot of older omni sites around in rural areas that were never sectorised.

You then have the issue of WCDMA and LTE technology and speed limitations..

I agree. But if the risk is genuine, why are phones even allowed on planes?

Guns are not allowed in carry on - they have to be checked in. Nail files ditto.

So why not cellphones?

I'm surprised cell phones are allowed on aircraft at all...

After all they do contain a Lithium battery, and we all know how dangerous they are, dont we.

(Just ask Boeing)

If you ship a lithium battery anywhere it requires special packaging, special delivery instructions, etc... and yet you can carry them on to an aircraft in a cell phone.

If electronic consumer devices (not just cell phones) are risky on aircraft, why are you allowed to use those devices once you're in the air?

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