Mobile phone signal interference... all lies??
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rmc, i'm always amazed by how little you aviation guys know about computers and telecoms 
you know a bazillion of very difficult things then stumble on the very basics .. never mind, it's quickly said.
wi-fi is what sets us free of these damned network cables.
It is what these people are using when they sit waiting to board, and now it works on the airplane too. With it you automatically have a phone because of somethign called skype, so we can envision anyone willing to spend $9.95 happily chatting away his trip.
I think it's the greatest invention after butter on the sliced bread.
you know a bazillion of very difficult things then stumble on the very basics .. never mind, it's quickly said.
wi-fi is what sets us free of these damned network cables.
It is what these people are using when they sit waiting to board, and now it works on the airplane too. With it you automatically have a phone because of somethign called skype, so we can envision anyone willing to spend $9.95 happily chatting away his trip.
I think it's the greatest invention after butter on the sliced bread.
Avoid imitations
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I get a bit tired of saying this (because a search of this website should reveal plenty of previous discussion on the matter) BUT a mobile phone on a UK network will set off the Aft Baggage Smoke/Fire warnings on our aircraft (S-76).
There is no fire extinguisher system in the bay so if this occurs, the Emergency Checklist requires us to land as soon as possible. This may mean landing in the nearest farmer's field. If we are IMC at the time, this is a very awkward situation.
The 737 pilot's answer is worrying and seems to stem from ignorance of the broader picture. He should be asked how he would feel about un-certified electrical transmitting equipment being used in his aircraft.....
We specifically emphasise that phones MUST be switched off before flight. Pax wanting to put luggage in the baggage compartment are asked to confirm that any phones therein are removed or switched completely off.
There is no fire extinguisher system in the bay so if this occurs, the Emergency Checklist requires us to land as soon as possible. This may mean landing in the nearest farmer's field. If we are IMC at the time, this is a very awkward situation.
The 737 pilot's answer is worrying and seems to stem from ignorance of the broader picture. He should be asked how he would feel about un-certified electrical transmitting equipment being used in his aircraft.....
We specifically emphasise that phones MUST be switched off before flight. Pax wanting to put luggage in the baggage compartment are asked to confirm that any phones therein are removed or switched completely off.
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ShyTorque, I completely agree with you, but wouldn't be time also for the Fire Warning system to be modified/shielded so not to trigger false alarms ?
Not to allow people to use their phone in fly, but to prevent you guys from having to land in a farm in case someone accidentally forgets the phone switched on.
Not to allow people to use their phone in fly, but to prevent you guys from having to land in a farm in case someone accidentally forgets the phone switched on.
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I am an avionics engineer and some years ago I was called to a 737 classic cockpit where the captain explained that the mcp (auto pilot mode control panel on the glareshield) was going nuts with the heading select and both course select displays changing wildly with confirmation on both ehsi's. Neither the crew or I had ever seen anything like it and after discussion believed it had to be some sort of interferance. On departing the cockpit to check things out downstairs in the electronics compartment I bumped into a passenger who was answering his mobile phone and had moved into the front galley to finish the call (right above electronics compartment). When the phone was switched off - problem disappeared. The phone brand/info was collected by crew and sent off thru the company channels.
I know airbus aircraft consider their aircraft to be impervious to such interferance, probably due to better shielding for their fly by wire setup. But maybe the the restriction on use of phones is just generic due to the fact you dont know which type of aircraft you will necessarily be travelling on. Besides how important is a call that cant wait till your on the ground - wasnt that long ago that the mobile phones didn't exist.
I know airbus aircraft consider their aircraft to be impervious to such interferance, probably due to better shielding for their fly by wire setup. But maybe the the restriction on use of phones is just generic due to the fact you dont know which type of aircraft you will necessarily be travelling on. Besides how important is a call that cant wait till your on the ground - wasnt that long ago that the mobile phones didn't exist.
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El ! I use wi-fi...was being facetious. What I was asking for in my last post was some enlightenment on whether or not this technology poses similar threats to some of our poorly shielded avionics. Shielding can = weight and that is the holly grail as far as manufacturers are concerned. None of them will want to put ANY additional weight into their designs to accommodate mobile phone useage on board.
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Thoughts..
Folks are well known for not doing what they are told - I'd rather expect something more stringent than "you must turn it off" if there was a serious danger? I would presume however that the effect is cumulative, and people being good keeps it to a managable level?
You're more likely to cause a spark by wearing a nice nylon shell suit than using a mobile - perhaps shell suits should be banned (PLEASE!!)
_modern_ mobile networks connect to multiple cells as a matter of course, it's how they do geo based services. Not a problem to the network. I can't comment on older analog phone systems which (at least 3-4years ago) were quite common in the US, and I'm not current on whether they've caught up!
Can you really get a signal that far up? Every mobile cell antenna I've ever been involved with is very much ground plane polarised.. I tend to find a vibration in my pocket as I descend into circuit is indicative of having forgotten to turn the thing off - it rarely if ever buzzes in flight.. (private pilot..) Which makes the whole thing a bit irrelevant anyway!
Folks are well known for not doing what they are told - I'd rather expect something more stringent than "you must turn it off" if there was a serious danger? I would presume however that the effect is cumulative, and people being good keeps it to a managable level?
You're more likely to cause a spark by wearing a nice nylon shell suit than using a mobile - perhaps shell suits should be banned (PLEASE!!)
_modern_ mobile networks connect to multiple cells as a matter of course, it's how they do geo based services. Not a problem to the network. I can't comment on older analog phone systems which (at least 3-4years ago) were quite common in the US, and I'm not current on whether they've caught up!
Can you really get a signal that far up? Every mobile cell antenna I've ever been involved with is very much ground plane polarised.. I tend to find a vibration in my pocket as I descend into circuit is indicative of having forgotten to turn the thing off - it rarely if ever buzzes in flight.. (private pilot..) Which makes the whole thing a bit irrelevant anyway!
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Originally Posted by Mark1234
Thoughts..
Can you really get a signal that far up? Every mobile cell antenna I've ever been involved with is very much ground plane polarised..
Can you really get a signal that far up? Every mobile cell antenna I've ever been involved with is very much ground plane polarised..
It may be unusual to get reception but I certainly had it that night.
Regards
csd
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I find some of the empirical testing made here a little worrying....
Some facts:
Avionics equipment is certified for radiated RF field immunity. Notice that this is 'RF field' and is in Volts/metre.
A cellphone has an RF output power of max 2Watts. The RF field generated depends on the distance from the antenna. A few feet from the antenna and the field will be around 10V/m. A few tens of feet and it will be below 1V/m.
However the cellphone is a portable device and could be placed a few inches from aircraft wiring etc and the field at that distance is MUCH higher and 'may' exceed the certified immunity level.
Also most equipment is tested for immunity in relatively small test chambers. It is not commercially viable to made radiated RF immunity testing of fully wired and integrated systems let alone complete commercial aircraft. But the overwhelming probabilty is that the total installation complies because the individual parts do. But there is no absolute guarantee.
Radiated RF susceptibility is a phenomena that requires a specific level of RF field on a discrete frequency (ie a resonance effect).
Wi-Fi is an example of spread spectrum technology. The RF power may be 100mW but that is the total RF power that is spread across many MHz. As an analogy you can think of Wi-Fi as being 100's of RF carriers of less than 1mW each. So the RF field at any discrete frequency will not represent any RF susceptibility threat.
No doubt when DO-160 version F arrives we will find that required testing and levels for RF immunity have been increased yet again.
ps: As for the comments about 25 year old TSO transceivers being immune. Quite possible, most of those I tested in the past were so insensitive that it was not suprising that they heard so little interference
Some facts:
Avionics equipment is certified for radiated RF field immunity. Notice that this is 'RF field' and is in Volts/metre.
A cellphone has an RF output power of max 2Watts. The RF field generated depends on the distance from the antenna. A few feet from the antenna and the field will be around 10V/m. A few tens of feet and it will be below 1V/m.
However the cellphone is a portable device and could be placed a few inches from aircraft wiring etc and the field at that distance is MUCH higher and 'may' exceed the certified immunity level.
Also most equipment is tested for immunity in relatively small test chambers. It is not commercially viable to made radiated RF immunity testing of fully wired and integrated systems let alone complete commercial aircraft. But the overwhelming probabilty is that the total installation complies because the individual parts do. But there is no absolute guarantee.
Radiated RF susceptibility is a phenomena that requires a specific level of RF field on a discrete frequency (ie a resonance effect).
Wi-Fi is an example of spread spectrum technology. The RF power may be 100mW but that is the total RF power that is spread across many MHz. As an analogy you can think of Wi-Fi as being 100's of RF carriers of less than 1mW each. So the RF field at any discrete frequency will not represent any RF susceptibility threat.
No doubt when DO-160 version F arrives we will find that required testing and levels for RF immunity have been increased yet again.
ps: As for the comments about 25 year old TSO transceivers being immune. Quite possible, most of those I tested in the past were so insensitive that it was not suprising that they heard so little interference
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Even if you can prove that they do not interfere with any aircraft system nor ground network including those not standard GSM such as the US and Caribbean etc. and those are two pretty big IF's there is yet a third hurdle which according to "INFORMATION AGE" is that:-
Quote-a recent IDC study of 50,000 American passengers found only 11% were in favour of phone use irrespective of the area of the plane.-endquote
The last thing passengers want is to be doing a long night flight in economy next to some selfish individual calling all his friends telling them that "I can't talk for long because I'm on the plane".
At the moment airlines prohibit their use, and that is known to the passenger when he books.
To take it out on the cabin crew by arguing at length that "my phone is ok because of this that or the other", is not on, but such behaviour is an everyday occurrence.
Quote-a recent IDC study of 50,000 American passengers found only 11% were in favour of phone use irrespective of the area of the plane.-endquote
The last thing passengers want is to be doing a long night flight in economy next to some selfish individual calling all his friends telling them that "I can't talk for long because I'm on the plane".
At the moment airlines prohibit their use, and that is known to the passenger when he books.
To take it out on the cabin crew by arguing at length that "my phone is ok because of this that or the other", is not on, but such behaviour is an everyday occurrence.
Last edited by Seat1APlease; 3rd Aug 2006 at 09:09.
Avoid imitations
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Originally Posted by el !
ShyTorque, I completely agree with you, but wouldn't be time also for the Fire Warning system to be modified/shielded so not to trigger false alarms ?
Not to allow people to use their phone in fly, but to prevent you guys from having to land in a farm in case someone accidentally forgets the phone switched on.
Not to allow people to use their phone in fly, but to prevent you guys from having to land in a farm in case someone accidentally forgets the phone switched on.
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Again ShyTorque, I do totally agree that there is no point in having cellphones working on airplanes.
But, on the other hand, you are operating one of the few types on which, according to your experience, you can reliably reproduce the effect of a cellphone interference to an airplane system. It may seem a little thing to you but despite all the discussion here there is very little literature on the subject.
I think this is a precious opportunity to correct a potentially dangerous situation that exist in your airplane.
You know that telling people to do or not do something is never enough. Passengers can be distracted, act in hurry, or for whatever reason still leave a phone on in cabin or in the baggage holder, in perfectly good faith. And then you are confronted to the awkard situation of making a landing call because the fire alarm goes off.
I understand the reluctance by the owner/operators of doing anything that is not absolutely necessary, but consider the huge amount of safety and securty procedures that they already undertake, also for legal protection reasons.
The solution is not said to be costly or complicated, RF interferences can be often solved with a bit of intuition, experience, and a 10c ferrite bead strategically placed.
But, on the other hand, you are operating one of the few types on which, according to your experience, you can reliably reproduce the effect of a cellphone interference to an airplane system. It may seem a little thing to you but despite all the discussion here there is very little literature on the subject.
I think this is a precious opportunity to correct a potentially dangerous situation that exist in your airplane.
You know that telling people to do or not do something is never enough. Passengers can be distracted, act in hurry, or for whatever reason still leave a phone on in cabin or in the baggage holder, in perfectly good faith. And then you are confronted to the awkard situation of making a landing call because the fire alarm goes off.
I understand the reluctance by the owner/operators of doing anything that is not absolutely necessary, but consider the huge amount of safety and securty procedures that they already undertake, also for legal protection reasons.
The solution is not said to be costly or complicated, RF interferences can be often solved with a bit of intuition, experience, and a 10c ferrite bead strategically placed.
On this topic, I have used mobiles (cellphones) in Australia up to 25,000 feet and had successful phone calls. This may have been with AMPS (analogue) but it may have also been with GSM (digital) technology.
Has anyone else ever been able to make successful calls at 25,000 ft or above?
Has anyone ever been able to make successful calls at 25,000 ft or above in the US?
Has anyone else ever been able to make successful calls at 25,000 ft or above?
Has anyone ever been able to make successful calls at 25,000 ft or above in the US?
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My personal opinion fwiw is that anyone who can't live without their cellphone for the few hours of a flight really ought to get some kind of a life. Radio phone facilities are available, I believe, on long haul flights so that 'really important' people can conduct their business and lesser mortals, like me, can avail themselves if there is something really important (although I can't imagine what).
When I was a kid I made a 'mobile phone' out of 2 tin cans and a garden-length string. If I shouted and used a longer string we could manage a few gardens range. It seems to me that everyone learned that way because, despite the modern marvels with their internal amplifiers, most people still SHOUT when using them. They are consequently intensely annoying to almost everyone within a garden's (or cabin's) range.
Imagine the scenario if cellphones were allowed:
Aircraft suffers cabin fire ('clever' selfish passenger who knows how to disable smoke detector having a smoke in the toilet perhaps). Fire fed by gallons of Duty Free alcohol in overhead lockers and escalates. Pilots carry out emergency descent and immediate diversion to nearest suitable airport. Unfortunately cabin crew cannot make themselves overheard with emergency instructions to pax because of cacophany of noise from 300+ cellphone users calling loved ones, lawyers, insurance companies etc, and many or all die in the extremely toxic smoke-filled cabin and confusion that ensues.
Just a thought. And as a retired airline pilot, who has been distracted by the noise through the headphones as my own phone (inadvertently left on) called its cavalry charge (or whatever they do), I would prefer that their general use in aircraft remains banned.
Regards
rts
When I was a kid I made a 'mobile phone' out of 2 tin cans and a garden-length string. If I shouted and used a longer string we could manage a few gardens range. It seems to me that everyone learned that way because, despite the modern marvels with their internal amplifiers, most people still SHOUT when using them. They are consequently intensely annoying to almost everyone within a garden's (or cabin's) range.
Imagine the scenario if cellphones were allowed:
Aircraft suffers cabin fire ('clever' selfish passenger who knows how to disable smoke detector having a smoke in the toilet perhaps). Fire fed by gallons of Duty Free alcohol in overhead lockers and escalates. Pilots carry out emergency descent and immediate diversion to nearest suitable airport. Unfortunately cabin crew cannot make themselves overheard with emergency instructions to pax because of cacophany of noise from 300+ cellphone users calling loved ones, lawyers, insurance companies etc, and many or all die in the extremely toxic smoke-filled cabin and confusion that ensues.
Just a thought. And as a retired airline pilot, who has been distracted by the noise through the headphones as my own phone (inadvertently left on) called its cavalry charge (or whatever they do), I would prefer that their general use in aircraft remains banned.
Regards
rts
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Better safe than sorry...several years ago I had one of the presidential limos on board our trash hauler...prior to takeoff both hsi started spinning, I finally asked the loadmaster if anything was going on in the back..the secret service boys had turned on the com radios in the limo, once turned off everything returned to normal. More recently with a tower controller in the jumpseat on an A320 we were delayed for thunderstorms, both engines shutdown...apu running. The controller asked if she could use her cellphone...our procedures allow for cellphone use on the ground prior to takeoff and after landing. I had no problem with it since we were not going anywhere for awhile. She made her call, and we could hear her over ground control...I asked her to turn it off than redo it just to see if it would happen again...it did! Sorry, I think we all know from flying aircraft long enough...that just because the tech says it can not happen, doesn't mean that it won't. If your need for being in touch is so critical...don't go.
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With "ionagh" info in mind.
Lets imagine the First/Business pax seated in seat 1A on a 747.
Seat 1A pax has a laptop with blue tooth and wifi on
A palm pilot wifi enabled to sinc with laptop
A mobile phone switched on due to what ever reason.
Top of decent all pax told to turn off electronic devices and pack them away.
Seat 1A waits till being told twice to do so and throws all of the above devices still switched on into carry on luggage and places in the forward coat locker less than 6 inches away from all 3 ILS antenna which is mounted on the other side of the bulk head.
Do we really know if this will effect the system or not?
Probably not if the antenna shielding is intact but it may be chaffed and getting worse with an intermittant defect the engineers can't find.
Then on the day a full cat 3 landing in pea soup is required seat 1A pax has done the above, the ILS antenna shielding has given out.
Next thing we are reading about controlled flight into terrain.
Aircraft incidents do not happen due to one failure they happen due to multiple failures, or as risk management people say, when the holes in the swiss cheese line up.
If pax in seat 74 B did the same with their electronic devices and placed them in the locker adjacent door 5 left, they may cause un commanded flushing of the vacuum toilets, no big deal but when seat 1A does it its catastrophic
Perhaps this is why one rule for all. Turn your phones off
Something else to add. GPS landing systems will be comming into vogue more and more. GPS radio waves operate around the 1.5 Gigahertz range which is close to the mobile phone frequency.
Lets imagine the First/Business pax seated in seat 1A on a 747.
Seat 1A pax has a laptop with blue tooth and wifi on
A palm pilot wifi enabled to sinc with laptop
A mobile phone switched on due to what ever reason.
Top of decent all pax told to turn off electronic devices and pack them away.
Seat 1A waits till being told twice to do so and throws all of the above devices still switched on into carry on luggage and places in the forward coat locker less than 6 inches away from all 3 ILS antenna which is mounted on the other side of the bulk head.
Do we really know if this will effect the system or not?
Probably not if the antenna shielding is intact but it may be chaffed and getting worse with an intermittant defect the engineers can't find.
Then on the day a full cat 3 landing in pea soup is required seat 1A pax has done the above, the ILS antenna shielding has given out.
Next thing we are reading about controlled flight into terrain.
Aircraft incidents do not happen due to one failure they happen due to multiple failures, or as risk management people say, when the holes in the swiss cheese line up.
If pax in seat 74 B did the same with their electronic devices and placed them in the locker adjacent door 5 left, they may cause un commanded flushing of the vacuum toilets, no big deal but when seat 1A does it its catastrophic
Perhaps this is why one rule for all. Turn your phones off
Something else to add. GPS landing systems will be comming into vogue more and more. GPS radio waves operate around the 1.5 Gigahertz range which is close to the mobile phone frequency.
Last edited by Bolty McBolt; 7th Aug 2006 at 05:56.
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>>Something else to add. GPS landing systems will be comming into vogue more and more. GPS radio waves operate around the 1 - 2 Gigahertz range which is close to the mobile phone frequency.<<
Dunno if it's close to the GPS frequency or not, but this was tried as well on my little un-scientific test.
If have two different GPS receivers on board and neither were bothered in the slightest.
Perhaps just lucky...
Dunno if it's close to the GPS frequency or not, but this was tried as well on my little un-scientific test.
If have two different GPS receivers on board and neither were bothered in the slightest.
Perhaps just lucky...
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Try operating coms on 133.4 and have one of your passengers operate a "Blackberry" phone. Not strictly a mobile phone in the conventional sense, but a mobile phone on a different frequency nonetheless.
133.4 is an exact harmonic, and reception of this frequency is perfect, reception of the phone caller that is! As for ATC, you can't hear a damned thing!
Regards,
Old Smokey
133.4 is an exact harmonic, and reception of this frequency is perfect, reception of the phone caller that is! As for ATC, you can't hear a damned thing!
Regards,
Old Smokey
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nuisance ring tone
I don't know .. it supposed to be funny story or what.
As we made the descend-turn to final on a VOR_DME letdown , a "WHOOP WHOOP PULL UP " sound twice heard then stop.After checking the approach profile we continued to land. On the ground I found out that it came from a cellphone of another pilot who accidentally left it. It use prerecorded GPWS test calls-out as the incoming-message warning tone ! Some so called smartphone can do that.
Not so smart after all .. i guess
As we made the descend-turn to final on a VOR_DME letdown , a "WHOOP WHOOP PULL UP " sound twice heard then stop.After checking the approach profile we continued to land. On the ground I found out that it came from a cellphone of another pilot who accidentally left it. It use prerecorded GPWS test calls-out as the incoming-message warning tone ! Some so called smartphone can do that.
Not so smart after all .. i guess
More bang for your buck
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I suspect that cell phone useage in petrol stations came about not because of the danger of explosions, but from the problems caused by powerfull cb radios that, when the PTT button was pressed, could caused the petrol pump electronics to under read the ammount delivered (mind you we're talking about 1/2 KW) and petrol companies were afraid that phones might do the same so the myth was created. After all they were not likely to say it might interfere with the pumps otherwise everyone would be trying it on . 
As for aircraft who wants to take the risk, it's along way down from 30,000ft
As for aircraft who wants to take the risk, it's along way down from 30,000ft
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Some of the technically competent articles make for interesting reading. Take, for instance, this article by Dr Bill Strauss in the June edition of Avionics Magazine ....