Mobile Phones on Aircraft CAA Report
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I arrange and observe EMC/EMI tests on flightdecks as part of the supply of our Electronic Techlogs (which use GSM technology to leave TechLog, etc on ground).
Our systems will not be allowed to even trial if the basic flightdeck test is not successfully completed - and these tests cannot happen without our DDP (Data & Design Performance test) being in place.
Flightdeck tests involve doing transmissions with flightdeck fired-up with engines off, then repeated with all engines on idle.
Results are tested visually (by two engineers) and electronically by a PCMCIA card in the avionics bay. This is then removed and analysed.
Each new aircraft (and variant) that is added to the fleet needs to be tested.
Finally, to emphasise radeng's post, these tests are only valid for that build of computer/phone card combination. It is our responsibility to verify each build of all equipment used. The DDP only covers one type of build; new build = new DDP = new EMI/EMC test.
All tests on all a/c covered (typically 737s and A320s) have been completely clear of any interference - but that's only because of the effort that goes into making sure that's the case!
Many of the electronic equipment allowed on f/decks at the moment don't need to undergo these tests as 'flightbag'solutions are not considered to be an integral part of the operation of a commercial a/c. The TechLog is a vital part of operating procedures, hence different standards of test.
Cello
Our systems will not be allowed to even trial if the basic flightdeck test is not successfully completed - and these tests cannot happen without our DDP (Data & Design Performance test) being in place.
Flightdeck tests involve doing transmissions with flightdeck fired-up with engines off, then repeated with all engines on idle.
Results are tested visually (by two engineers) and electronically by a PCMCIA card in the avionics bay. This is then removed and analysed.
Each new aircraft (and variant) that is added to the fleet needs to be tested.
Finally, to emphasise radeng's post, these tests are only valid for that build of computer/phone card combination. It is our responsibility to verify each build of all equipment used. The DDP only covers one type of build; new build = new DDP = new EMI/EMC test.
All tests on all a/c covered (typically 737s and A320s) have been completely clear of any interference - but that's only because of the effort that goes into making sure that's the case!
Many of the electronic equipment allowed on f/decks at the moment don't need to undergo these tests as 'flightbag'solutions are not considered to be an integral part of the operation of a commercial a/c. The TechLog is a vital part of operating procedures, hence different standards of test.
Cello
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The old "it must be the A/C designers fault" argument
411A misses one vital point; a lot of systems and even aircraft still in regular daily use were developed BEFORE mobile phones, CDROMS, Laptops or other modern gizmos were even thought of. So it is fairly pointless to say it is a problem for the design authority or manufacturer as they had no knowledge of potentially disruptive technology at the time the unit was signed off! They did the best with available information at the time, and considering the amount of RF emissions in the ether these days, did a good job IMHO. I for one perfer to err on the side of caution, having seen some interesting AP effects on a Saratoga which seemed to be related to a powered-up PCS phone in the R/H pax bag. And yes I do normally ask that pax turn off any electronics as part of the pre-flight safety briefing.
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I have personally had two cases of RF interference with the A/C systems. The first many moons ago approaching TOD for Man in a 737-200 and the A/P pitch channel dropped out. It was re-engaged, and a few seconds later dropped out again, with a momentary stickshake (It is supposed to disconnect on stickshake activation). Continued uneventfully to MAN. Sitting scratchiing heads as to how to write it up---enter the Engineer, whio takes one look at the beginning of the entry (A/P Problem) and says "What's that, a stickshake and pitch channel dropout? Third one this morning fellas, we reckon it's the military in North Wales testing radars or somesuch!" All were on 737-200's and would look like signal injection into the stall warning system.
The second was on a 744, Short Finals Singapore. I heard a very distinct series of dialing tones on my headset-(the F/O didn't) and all the #2 ILS & Nav. info blanked with associated flags and warnings. I happened to be on the PA at the time securing the cabin, so added a request for whoever was using the phone to desist. Nav info came back after about 30 sec. The Cabin Crew confirmed that a passenger was using a phone at the time, but they were secured, so unable to stop her.
These two incidents are enough to make me a believer!
The second was on a 744, Short Finals Singapore. I heard a very distinct series of dialing tones on my headset-(the F/O didn't) and all the #2 ILS & Nav. info blanked with associated flags and warnings. I happened to be on the PA at the time securing the cabin, so added a request for whoever was using the phone to desist. Nav info came back after about 30 sec. The Cabin Crew confirmed that a passenger was using a phone at the time, but they were secured, so unable to stop her.
These two incidents are enough to make me a believer!
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There is a simple way of avoiding 99% of these occurences.
A good PA, either fromt the CC or the pilots.
When I first made Purser, I realised after 2 weeks/35 stretches that the standard company text about moblie phones was useless, since no pasengers ever checked their phones.
So I modified it to the following:
For the benefit of the non-English speakers I hold up my own mobile,wave it around a bit and at the end of the sentence make the universal throat-slashing movement.
And each & every stretch at least 2 or 3 pax get up and take out their phones from the overhead luggage bin to check/switch it off! 
I've proposed to change the standard non-funtional text, but comp not interested. Claiming that it is too much text and will bore the pax. Since I leave out most of the obfuscating commercial blah-blah, my text is actually much shorter than most Pursers', and the whole safety spiel always has people's attention, even the safety demo is watched with wry amusement and or alacrity.
I am satisfied that on "my" flights at least, the danger of this particular phone sh!t happening is well reduced. Added benefit is passengers who appreciate understanding why they have to do certain things.
They don't like being talked down to, the way we often do on-board. They are not kindergarten inmates, but will behave as such if we treat them condescendingly.
Passengers are just like humans, treat them with respect, appeal to their understanding and they actually enjoy playing an active role in the safety effort.
<end of ride on hobby horse>
A good PA, either fromt the CC or the pilots.
When I first made Purser, I realised after 2 weeks/35 stretches that the standard company text about moblie phones was useless, since no pasengers ever checked their phones.
So I modified it to the following:
Ladies and gentlemen, your mobile phone on stand-by, even if you are NOT talking into it, WILL search for contact with a ground station. This continuing search CAN interfere with the navigational equipment in the cockpit. That is potentially dangerous. We don't want that, you don't want it, so please make sure that your moblie phone is switched off COMPLETELY!
For the benefit of the non-English speakers I hold up my own mobile,wave it around a bit and at the end of the sentence make the universal throat-slashing movement.
And each & every stretch at least 2 or 3 pax get up and take out their phones from the overhead luggage bin to check/switch it off! I've proposed to change the standard non-funtional text, but comp not interested. Claiming that it is too much text and will bore the pax. Since I leave out most of the obfuscating commercial blah-blah, my text is actually much shorter than most Pursers', and the whole safety spiel always has people's attention, even the safety demo is watched with wry amusement and or alacrity.
I am satisfied that on "my" flights at least, the danger of this particular phone sh!t happening is well reduced. Added benefit is passengers who appreciate understanding why they have to do certain things.
They don't like being talked down to, the way we often do on-board. They are not kindergarten inmates, but will behave as such if we treat them condescendingly.
Passengers are just like humans, treat them with respect, appeal to their understanding and they actually enjoy playing an active role in the safety effort.
<end of ride on hobby horse>
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FlapsForty - Good for you. As a passenger I'd be very happy to hear you say that.
BBC reports a Siemens airborne trial of 3G mobile equipment - sounds like they are so worried by the absence of demand for 3G on the ground that they want to use it in the sky instead.
http://news.bbc.co.uk/1/hi/technology/2991977.stm
BBC reports a Siemens airborne trial of 3G mobile equipment - sounds like they are so worried by the absence of demand for 3G on the ground that they want to use it in the sky instead.
http://news.bbc.co.uk/1/hi/technology/2991977.stm
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I would like to support radeng’s comments about EMC. For products placed on the market in Europe there is a New Approach Directive numbered 89/336/EEC. This pertains to the limiting of emissions from and immunity of every, well almost every (with small exceptions), piece of electrical equipment, which is “Placed on the market” or “Taken into use” within the European Union.
Sounds OK in principle, BUT a couple of points to consider…….
The EMC Directive (89/336EEC) and the statutory instruments that enshrine this into law in member states DO NOT prescribe that the manufacturer makes ANY measurements; it just states that the product must comply with what are called the ‘Essential Protection Requirements’ of the said Directive. Now most manufacturers will make measurements in order to gain evidence that they have satisfied the principles of due diligence in their application of this Directive. But remember all the manufacturer has to do, as a minimum, is make a declaration that their product complies. These declarations are normally supplied with the product when sold and are the pieces of paper we all throw away when we open the box!
This principle is called manufacturer "Self - Declaration" and it does not have to be confirmed by any body independant of the manufacturer prior to the goods being available for sale and (ab)use in aircraft.
The second problem is that although the Directive does state that ALL products must comply i.e. each and every product that comes of the line; in manufacturing, however, there are always tolerances. Commercialism being what it is means that the design of the product is such that the measurements are made and results accepted right up to the limit without any thought of measurement uncertainty. This ensures that the bill of materials and component count remains as low as possible and the profits as high as possible. The reason this is important is that if you want to reduce the ‘level of emission’ this might mean the inclusion of an extra component (capacitor, choke, screen, bonding, can etc) not a problem in small production run, but if you make a million products week as some mobile phone manufacturers do, then this extra component is going to cost you maybe $100K a week (assuming the extra component costs only 10 cents).
The reason I thought was worthwhile posting is because there almost certainly WILL be some samples of the product run that FAIL these protection requirements. The police(ing) of the EMC directive is in Europe at best patchy, in some areas even relying on competitors measuring each other’s products in order to gain commercial advantage by forcing withdrawal of sale.
In my view this means two things
a) There most definitely ARE samples of products out there that fail to meet limits prescribed in the technical standards supporting the statutory legal instruments. I have quoted the example of the EMC directive but the principles apply equally to CFR 47 – FCC Rules parts 15, 18, 22, 24, Industry Canada regulations, JATE/TELEC, AUS/NZ, 3GPP specifications or whatever region of the world or technology sector you care to mention.
b) Be aware that when using the term ‘regulation’ in the context of commercial products the reasons for regulation are different i.e. in the world of aviation the primary drive for EMC regulation may be that of safety, in the commercial world the primary drive for EMC regulation may NOT be. There are two reasons why the EMC Directive, 89/336/EEC was brought in Europe in 1996. Firstly, to provide free passage of goods throughout Europe and ONLY secondly to try to minimize ElectroMagnetic pollution. Furthermore, equipment is said to be fit for purpose IN IT’S INTENDED ENVIRONMENT. The intended environment for mobile phones for example is not in an aircraft and therefore the limits in the standards are not designed with aircraft operations is mind.
Sorry if this is a boring post but there is a good reason. The reason is that someone once said to me that there is a perception amongst PPLs that there is an ATCO out there clearing the skies for me. I know this is not true. Commanders and F/Os don’t think there is a heavy weight regulatory body out there with the primary objective of making sure that all products are compatible and that they will not interfere with your aircraft systems……..there is no such beast. Assume all products fail and all possibilities of interference exist in your aircraft.
Regards
Barney
P.S. Just as an after thought the above only applies to unintentional radiation and does not cover intentional radiation e.g. Code Division/Frequency Modulation/Gaussian Minimum Shift Keying type intentional signals mentioned above that are used in cell phones. The fact that a particular phone does not interfere can be because the type of modulation involved does not interfere, the frequency is not related/inter-related with aircraft systems, positioning in the cabin, power output of the transmitter etc etc etc. All these factors are not controlled by either of the pilots. Permitting this at perhaps 300ft AGL at 200 kts is a sailing a little close to the wind I would say
Sounds OK in principle, BUT a couple of points to consider…….
The EMC Directive (89/336EEC) and the statutory instruments that enshrine this into law in member states DO NOT prescribe that the manufacturer makes ANY measurements; it just states that the product must comply with what are called the ‘Essential Protection Requirements’ of the said Directive. Now most manufacturers will make measurements in order to gain evidence that they have satisfied the principles of due diligence in their application of this Directive. But remember all the manufacturer has to do, as a minimum, is make a declaration that their product complies. These declarations are normally supplied with the product when sold and are the pieces of paper we all throw away when we open the box!
This principle is called manufacturer "Self - Declaration" and it does not have to be confirmed by any body independant of the manufacturer prior to the goods being available for sale and (ab)use in aircraft.
The second problem is that although the Directive does state that ALL products must comply i.e. each and every product that comes of the line; in manufacturing, however, there are always tolerances. Commercialism being what it is means that the design of the product is such that the measurements are made and results accepted right up to the limit without any thought of measurement uncertainty. This ensures that the bill of materials and component count remains as low as possible and the profits as high as possible. The reason this is important is that if you want to reduce the ‘level of emission’ this might mean the inclusion of an extra component (capacitor, choke, screen, bonding, can etc) not a problem in small production run, but if you make a million products week as some mobile phone manufacturers do, then this extra component is going to cost you maybe $100K a week (assuming the extra component costs only 10 cents).
The reason I thought was worthwhile posting is because there almost certainly WILL be some samples of the product run that FAIL these protection requirements. The police(ing) of the EMC directive is in Europe at best patchy, in some areas even relying on competitors measuring each other’s products in order to gain commercial advantage by forcing withdrawal of sale.
In my view this means two things
a) There most definitely ARE samples of products out there that fail to meet limits prescribed in the technical standards supporting the statutory legal instruments. I have quoted the example of the EMC directive but the principles apply equally to CFR 47 – FCC Rules parts 15, 18, 22, 24, Industry Canada regulations, JATE/TELEC, AUS/NZ, 3GPP specifications or whatever region of the world or technology sector you care to mention.
b) Be aware that when using the term ‘regulation’ in the context of commercial products the reasons for regulation are different i.e. in the world of aviation the primary drive for EMC regulation may be that of safety, in the commercial world the primary drive for EMC regulation may NOT be. There are two reasons why the EMC Directive, 89/336/EEC was brought in Europe in 1996. Firstly, to provide free passage of goods throughout Europe and ONLY secondly to try to minimize ElectroMagnetic pollution. Furthermore, equipment is said to be fit for purpose IN IT’S INTENDED ENVIRONMENT. The intended environment for mobile phones for example is not in an aircraft and therefore the limits in the standards are not designed with aircraft operations is mind.
Sorry if this is a boring post but there is a good reason. The reason is that someone once said to me that there is a perception amongst PPLs that there is an ATCO out there clearing the skies for me. I know this is not true. Commanders and F/Os don’t think there is a heavy weight regulatory body out there with the primary objective of making sure that all products are compatible and that they will not interfere with your aircraft systems……..there is no such beast. Assume all products fail and all possibilities of interference exist in your aircraft.
Regards
Barney
P.S. Just as an after thought the above only applies to unintentional radiation and does not cover intentional radiation e.g. Code Division/Frequency Modulation/Gaussian Minimum Shift Keying type intentional signals mentioned above that are used in cell phones. The fact that a particular phone does not interfere can be because the type of modulation involved does not interfere, the frequency is not related/inter-related with aircraft systems, positioning in the cabin, power output of the transmitter etc etc etc. All these factors are not controlled by either of the pilots. Permitting this at perhaps 300ft AGL at 200 kts is a sailing a little close to the wind I would say
Last edited by Barney_Gumble; 6th May 2003 at 19:24.
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Perhaps there is another safety aspect: that of the passenger making the call.
Despite all the publicity and griping large numbers of people are still incapable of speaking into a mobile phone at a normal volume: they have to shout.
Aircraft are noisy inside: maybe not as loud as a train but more or less constant background white noise. At least on a train you can get up and walk around or lean out of the way. Being stacked for 40 minutes over London and having someone blathering away about what he did/will do in Amsterdam with whom will drive even the calmest person insane.
And then there's the ring tones. Can you imagine trying to sleep on a long haul flight, say LHR <-> HKG, and having that ghastly Nokia tune going every few minutes? At the Nokia default volume of too-bloody-loud? Bad enough down the front - imagine what it's like in cattle class where your head is sandwiched between up to 10 people.
Now add a few beers into the mix....
Incidentally, anybody know how much you could be stung for in roaming charges on a flight from UK to Australia? That's a lot of networks to connect to.....
Despite all the publicity and griping large numbers of people are still incapable of speaking into a mobile phone at a normal volume: they have to shout.
Aircraft are noisy inside: maybe not as loud as a train but more or less constant background white noise. At least on a train you can get up and walk around or lean out of the way. Being stacked for 40 minutes over London and having someone blathering away about what he did/will do in Amsterdam with whom will drive even the calmest person insane.
And then there's the ring tones. Can you imagine trying to sleep on a long haul flight, say LHR <-> HKG, and having that ghastly Nokia tune going every few minutes? At the Nokia default volume of too-bloody-loud? Bad enough down the front - imagine what it's like in cattle class where your head is sandwiched between up to 10 people.
Now add a few beers into the mix....
Incidentally, anybody know how much you could be stung for in roaming charges on a flight from UK to Australia? That's a lot of networks to connect to.....
Ohcirrej
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From the ATC point of view if I may.......
Was the witness first hand a couple of years ago Down Under. A certain ATC Assistant who was flying during the many hours he was working outside Air Services Australia, used to walk about the old Brisbane AACC with his phone on. On walking past a radar screen once (it was the old IRDS RAS/RIS screen on the Approach Team...) it went all "Scooby Doo" in front of everybody. At the time, it was kind of a laugh. But a few day later, the signs went up around about the centre, instructing people to turn phones off.
IMHO, nobody is that important they need to be "contactable"!. And if you think you do.....well, let it not be up to me to judge.
J.
Was the witness first hand a couple of years ago Down Under. A certain ATC Assistant who was flying during the many hours he was working outside Air Services Australia, used to walk about the old Brisbane AACC with his phone on. On walking past a radar screen once (it was the old IRDS RAS/RIS screen on the Approach Team...) it went all "Scooby Doo" in front of everybody. At the time, it was kind of a laugh. But a few day later, the signs went up around about the centre, instructing people to turn phones off.
IMHO, nobody is that important they need to be "contactable"!. And if you think you do.....well, let it not be up to me to judge.
J.
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Short Review of the Report
Having just had a brief read of the report, I think that this represents an excellent start to a full investigation. The boundaries of this particular report are narrow for practical measurement reasons and I feel that they have only really scratched the surface insofar as.......
1. Only a single frequency per band was used for each measurement. In reality many frequencies are used in each band in mobile communications and the affect of changing the frequency can be marked and dependant on the unintentional "Q" of the reception mechanism within the avionics. This means how easy the system will respond to an interfering frequency and how accurate the accidental tuning has to be. The higher the "Q" the lower the "chances" of interferences, but when the tuning is on target the worse the interference possibilities.
2. Only single frequency simplex has been simulated and in real life half or full duplex possibilities are involved.
3. Only circuit switching on single timeslot transmission has been simulated. Present and future communications protocols are/will be using multi-slot and packet switching techniques.
4. The field strengths do represent that which would be expected at 30cm from the source, but this level of field strength increases remarkably as the source is brought closer to the victim (i.e. the phone is brought closer to the avionics). This can be as a square or cube law relationship depending on the distance and the interfering frequency and the interfering mechanism either low impedance current flowing through the cable or high impedance voltage presented across two points in the control circuits presenting an interfering potential difference
3. Lastly and probably most importantly is that the measurements have been necessarily restricted to Gaussian Min Shift Keying (i.e. GSM). There are other widely used schemes in different areas of the world.
Code Division Multiple Access (CDMA) - US
Wide Band Code Division Multiple Access (WCDMA/3G/UTRA/CDMA2000)
TDMA - Time Division Multiple Access - US
AMPS - US
DAMPS - US
TACS - South America/China/Middle East etc
PDC - Japan
Again probably boring and techy BUT my point is that even with the sub-set of possible interferences mechanisms that this report has focused on the measurements and the report still give supporting evidence of interference effects.......I wonder what happens in the real world!
In summary, IMHO we should keep mobile phones switched off during all phases of flight as there are currently too many unknowns and variables to make a proper scientific judgement
Cheers Andy
1. Only a single frequency per band was used for each measurement. In reality many frequencies are used in each band in mobile communications and the affect of changing the frequency can be marked and dependant on the unintentional "Q" of the reception mechanism within the avionics. This means how easy the system will respond to an interfering frequency and how accurate the accidental tuning has to be. The higher the "Q" the lower the "chances" of interferences, but when the tuning is on target the worse the interference possibilities.
2. Only single frequency simplex has been simulated and in real life half or full duplex possibilities are involved.
3. Only circuit switching on single timeslot transmission has been simulated. Present and future communications protocols are/will be using multi-slot and packet switching techniques.
4. The field strengths do represent that which would be expected at 30cm from the source, but this level of field strength increases remarkably as the source is brought closer to the victim (i.e. the phone is brought closer to the avionics). This can be as a square or cube law relationship depending on the distance and the interfering frequency and the interfering mechanism either low impedance current flowing through the cable or high impedance voltage presented across two points in the control circuits presenting an interfering potential difference
3. Lastly and probably most importantly is that the measurements have been necessarily restricted to Gaussian Min Shift Keying (i.e. GSM). There are other widely used schemes in different areas of the world.
Code Division Multiple Access (CDMA) - US
Wide Band Code Division Multiple Access (WCDMA/3G/UTRA/CDMA2000)
TDMA - Time Division Multiple Access - US
AMPS - US
DAMPS - US
TACS - South America/China/Middle East etc
PDC - Japan
Again probably boring and techy BUT my point is that even with the sub-set of possible interferences mechanisms that this report has focused on the measurements and the report still give supporting evidence of interference effects.......I wonder what happens in the real world!
In summary, IMHO we should keep mobile phones switched off during all phases of flight as there are currently too many unknowns and variables to make a proper scientific judgement
Cheers Andy
Last edited by Barney_Gumble; 8th May 2003 at 15:18.
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Some excellent points being made here. In particular, Flaps' on-board PA is excellent. The PA system should be used for safety briefings and only safety briefings. There is no place for "If you would like to book a hire car, we suggest you go to Fred's in the arrivals hall - or if you need a hotel we've arranged special rates with the XYZ Hotel..." which just tend to persuade the passengers to blank it all out. I want to be sure that pax sit up and listen when it comes on.
Those of the pro-phone lobby who rest their claims on "Well, I've flown x thousands of hours with my mobile phone on and I haven't had a problem" do not assist the argument, in that it does not establish that other people haven't had problems.
What does anyone think of the suggestion that I've seen elsewhere that mobile phones should be switched off before boarding? It is quite possible to install archway detectors that will scan a passenger as he goes through.
Since in LVP's, aircraft rely quite considerably on the avionics to navigate successfully to the end of the (hopefully) correct runway, how would people feel about having mobile phone use permitted before takeoff?
I feel that the CAA paper is a very welcome starting point. I suggest that ICAO should be involved in this, so that a set of rules that is coherent across airlines and national boundaries should be encoded.
Those of the pro-phone lobby who rest their claims on "Well, I've flown x thousands of hours with my mobile phone on and I haven't had a problem" do not assist the argument, in that it does not establish that other people haven't had problems.
What does anyone think of the suggestion that I've seen elsewhere that mobile phones should be switched off before boarding? It is quite possible to install archway detectors that will scan a passenger as he goes through.
Since in LVP's, aircraft rely quite considerably on the avionics to navigate successfully to the end of the (hopefully) correct runway, how would people feel about having mobile phone use permitted before takeoff?
I feel that the CAA paper is a very welcome starting point. I suggest that ICAO should be involved in this, so that a set of rules that is coherent across airlines and national boundaries should be encoded.
Fortunately, immunity is being recognised as being important, although it has been said that it will be several years before all civil aircraft reach an immunity level of 20Volts/metre. The International Electrotechnical Committee recommend an immunity level of 3V/m for domestic and light industrial environments: 10V/m is used for maritime electronics. Domestic radio and TV sets only need to meet 1.8V/m, while normal telephone manufacturers have been pressing for no limits at all on telephones! Tough for anyone living near a broadcast station. many years ago now, the microphones in the telephones at Manchester airport were replaced by the then new 'electret' ones: the result was that everyone telephoning had a strong background of Manchester ATC! So much for the telephone manufacturers arguments!
Radiation is another matter: even without cell phones, the current proposals on Power Line Telecommunications, connecting your computer via the power network are likely to mean that a lot of HF radio becomes unuseable. Because of the number of radiators involved, that's quite likely to mean that HF from mid Atlantic won't make it - hopefully, all aircraft will be using (more expensive) satellite comms by then........
Radiation is another matter: even without cell phones, the current proposals on Power Line Telecommunications, connecting your computer via the power network are likely to mean that a lot of HF radio becomes unuseable. Because of the number of radiators involved, that's quite likely to mean that HF from mid Atlantic won't make it - hopefully, all aircraft will be using (more expensive) satellite comms by then........
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radeng: I though the ITU spectrum rules (as well as regional and national ones) stated tha tcertain services, for example aeronautical mobile communications, were allocated certain frequencies and anyone who did things (like communications over power lines) that resulted in emissions that interfered with the service had to change their way of doing things so as to not interfere or knock it off.
In the real world I know it is never this clean or simple, but even ITU should recognize that this kind of interference is a problem. Then again, maybe they want to push everybody to satcom and cell phones so "service providers" can charge by the minute, bit or whatever.
In the real world I know it is never this clean or simple, but even ITU should recognize that this kind of interference is a problem. Then again, maybe they want to push everybody to satcom and cell phones so "service providers" can charge by the minute, bit or whatever.
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While I've no experience of avionics, I do work for a major mobile phone manufacturer as an RF design engineer, working on handsets.
The reason I'm posting is to second Radeng, and Andy. To the anecdotal tales of "well I've used my phone in an airliner and never had a problem", I'd say "Yet!".
Part of the problem is that with a metal box the signal from the phone or CDrom or whatever gets reflected around creating peaks and troughs of signal. If you get constructive interference at the wrong point energy will get conducted onto wiring looms etc. So a small change in the position of the radiating object can create large changes to effect on other equipment. And as such it is going to be difficult to test in a lab/EMC house environment.
In addition because basestations tend to beam the signals they produce horizontally rather than vertically, a phone in an aeroplane will spend a lot of time trying to camp onto a network. As a phone tries to camp on it broadcasts to the basestation to try and register. Therefore lots of potential for interference...
I've seen phones interfere with other phones, PCs, televisions, and radios, and spent months of my life trying to shield and screen things. To my mind it's just not worth the risk of switching a phone on in a plane. It is as simple as that.
Cheers
John
The reason I'm posting is to second Radeng, and Andy. To the anecdotal tales of "well I've used my phone in an airliner and never had a problem", I'd say "Yet!".
Part of the problem is that with a metal box the signal from the phone or CDrom or whatever gets reflected around creating peaks and troughs of signal. If you get constructive interference at the wrong point energy will get conducted onto wiring looms etc. So a small change in the position of the radiating object can create large changes to effect on other equipment. And as such it is going to be difficult to test in a lab/EMC house environment.
In addition because basestations tend to beam the signals they produce horizontally rather than vertically, a phone in an aeroplane will spend a lot of time trying to camp onto a network. As a phone tries to camp on it broadcasts to the basestation to try and register. Therefore lots of potential for interference...
I've seen phones interfere with other phones, PCs, televisions, and radios, and spent months of my life trying to shield and screen things. To my mind it's just not worth the risk of switching a phone on in a plane. It is as simple as that.
Cheers
John
Join Date: Dec 1999
Location: Hertfordshire UK
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Well said SSC. Use of the mobile phone is a highly anti-social behaviour in close proximity to strangers and can be banned on those grounds alone without reference to the safety arguments.
As far as risk management goes, someone mentioned the dangers of smoking in aircraft toilets as being equivalent to using a mobile. Surely it can't be beyond the wonders of modern technology to provide "safe booths" on larger aircraft where passengers can make calls and smoke to their hearts content under the watchful eye of the cabin staff. This would satisfy consumer demand and stop the problems being driven underground.
I readily admit to leaving my mobile accidentally switched on in the flight deck "da da da...da da da...da da da" so there must be dozens of passengers doing the same thing. I always permit passengers to use mobiles on the ground in cases of delay or unusual circumstances etc.
As far as risk management goes, someone mentioned the dangers of smoking in aircraft toilets as being equivalent to using a mobile. Surely it can't be beyond the wonders of modern technology to provide "safe booths" on larger aircraft where passengers can make calls and smoke to their hearts content under the watchful eye of the cabin staff. This would satisfy consumer demand and stop the problems being driven underground.
I readily admit to leaving my mobile accidentally switched on in the flight deck "da da da...da da da...da da da" so there must be dozens of passengers doing the same thing. I always permit passengers to use mobiles on the ground in cases of delay or unusual circumstances etc.
Iron City,
The ITU are unfortunately always way behind in these matters. In fact, ITU workings are a bit like elephants mating - a lot of trumpeting and noise and then nothing happens for a couple of years. (Radeng goes to some ITU meetings, for his sins).
Currently, the FCC is investigating PLC (Power Line Communications) with a view to its interference potentials. The matter was brought up in the UK some time ago: Tony Blair's desire for 'Broadband Britain' meant that when there was a Cabinet committee meeting, the civil servants who realised that opposing the proposals would be bad for promotion rolled over with their feet in the air. NATO and the armed forces are worried about it - they are big users of HF, even in these days of military satellites: people from the UK Radiocommunications Agency, bless them, are fighting as hard as they can to keep the radio spectrum clean, but I understand that most other UK government departments would rather not rock the boat.
The European Commission also want PLC, and have various specious arguments about the users of HF being a minority. There have been mutterings about a Human Rights case, in that ethnic minorities in the EU wishing to receive broadcasts from their native countries that aren't available by satellite would have their Human Rights infringed. Whether that will get anywhere I don't know - I doubt it.
But using satellite is a good way to improve the satellite comms people's profits!
The ITU are unfortunately always way behind in these matters. In fact, ITU workings are a bit like elephants mating - a lot of trumpeting and noise and then nothing happens for a couple of years. (Radeng goes to some ITU meetings, for his sins).
Currently, the FCC is investigating PLC (Power Line Communications) with a view to its interference potentials. The matter was brought up in the UK some time ago: Tony Blair's desire for 'Broadband Britain' meant that when there was a Cabinet committee meeting, the civil servants who realised that opposing the proposals would be bad for promotion rolled over with their feet in the air. NATO and the armed forces are worried about it - they are big users of HF, even in these days of military satellites: people from the UK Radiocommunications Agency, bless them, are fighting as hard as they can to keep the radio spectrum clean, but I understand that most other UK government departments would rather not rock the boat.
The European Commission also want PLC, and have various specious arguments about the users of HF being a minority. There have been mutterings about a Human Rights case, in that ethnic minorities in the EU wishing to receive broadcasts from their native countries that aren't available by satellite would have their Human Rights infringed. Whether that will get anywhere I don't know - I doubt it.
But using satellite is a good way to improve the satellite comms people's profits!
