Mobile Phones
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Mobile Phones
If you were planning to use your mobile phone in a light aircraft or microlight while in the air, how would you check on the ground that it will not cause interference with your aircrafts avionics?
Yes, I know that all CAA and Ofcom recommendations are not to use a mobile in the air unless its an emergency - life threatening – situation. Talking to pilots and passengers the reality is that there are many people out there currently doing this on a regular basis.
Let’s not go down the should you or shouldn’t you route, it’s an old and well rehearsed argument, but let’s look at what can be done to minimise any risk by identifying the checks to be made beforehand.
Yes, I know that all CAA and Ofcom recommendations are not to use a mobile in the air unless its an emergency - life threatening – situation. Talking to pilots and passengers the reality is that there are many people out there currently doing this on a regular basis.
Let’s not go down the should you or shouldn’t you route, it’s an old and well rehearsed argument, but let’s look at what can be done to minimise any risk by identifying the checks to be made beforehand.
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One could borrow an avionics tester (e.g. an IFR4000), turn the signal level down to the minimum at which the instruments don't quite flag out, and then play around with the phone.
Unless you have crap wiring/grounding (itself quite common in GA) you are unlikely to see any interference.
Unless you have crap wiring/grounding (itself quite common in GA) you are unlikely to see any interference.
You can quite often hear a phone in the aircraft on either the radio or intercom and it is identified by a rapid ticking noise when it sends packets of data. It can also go out on your transmission and be picked up by ATC. I have been told by ATC to tell my passenger to switch their phone off.
The bursts of data are more likely to be picked up by audio systems that rectify the RF, than any instrumentation.
Place you mobile near a BT phone and you will probably hear a similar noise.
The bursts of data are more likely to be picked up by audio systems that rectify the RF, than any instrumentation.
Place you mobile near a BT phone and you will probably hear a similar noise.
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Indeed, but I think this is caused by the phone's RF messing up the circuitry in the headset, or the mike.
That would not be suprising. I get that too, especially with the satellite phone.
But I have never seen interference with any VHF or UHF equipment.
Nevertheless, I switch off the satphone, and try to make sure all mobiles are switched off (and that includes the Ipad/3G
) if flying an ILS in IMC.
That would not be suprising. I get that too, especially with the satellite phone.
But I have never seen interference with any VHF or UHF equipment.
Nevertheless, I switch off the satphone, and try to make sure all mobiles are switched off (and that includes the Ipad/3G
) if flying an ILS in IMC.
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According to CAA PAPER 2003/3 “Effects of Interference from Cellular Telephones on Aircraft Avionic Equipment” the problems caused by a mobile phone 30 cm from an avionics and instrument panel are:
When asking my question I had in mind some simple practical checks a pilot could make with just a mobile phone and observing its effects on the aircraft.
There are lots of adverts in the aviation magazines for headsets that have a capability for a Bluetooth connection to a mobile phone. I thought that maybe using one of these headsets or something similar, it would be possible to hold the phone in front of the avionics stack, or in various positions around the cockpit, while making and receiving a few test calls.
Observing the avionics behavior during the test calls might then give a rough indication of any potential interference problems?
- Compass froze or overshot actual magnetic bearing.
- Instability of indicators.
- Digital VOR navigation bearing display errors up to 5 degrees.
- VOR navigation To/From indicator reversal.
- VOR and ILS course deviation indicator errors with and without a failure flag.
- Reduced sensitivity of the ILS Localiser receiver.
- Background noise on audio outputs.
When asking my question I had in mind some simple practical checks a pilot could make with just a mobile phone and observing its effects on the aircraft.
There are lots of adverts in the aviation magazines for headsets that have a capability for a Bluetooth connection to a mobile phone. I thought that maybe using one of these headsets or something similar, it would be possible to hold the phone in front of the avionics stack, or in various positions around the cockpit, while making and receiving a few test calls.
Observing the avionics behavior during the test calls might then give a rough indication of any potential interference problems?
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Compass froze or overshot actual magnetic bearing - NO.
Instability of indicators - NO.
Digital VOR navigation bearing display errors up to 5 degrees - NO.
VOR navigation To/From indicator reversal - NO.
VOR and ILS course deviation indicator errors with and without a failure flag - NO.
Reduced sensitivity of the ILS Localiser receiver - NO.
Background noise on audio outputs - YES, although nothing major.
That's purely a response from me in regard to my own aeroplane. I have considerable disdain for bad science, and have tried my level best to prove that any of these assertions hold any water by deliberating dialling my home line to maximise RF activity then shoving the phone as close to these "sensitive" instruments as possible. Nothing... absolutely nothing.
That said, as mentioned above I'm not a scientist and I'll keep them switched off during serious stuff, like flying instrument approaches. They are however very useful on a nice VMC day for calling a taxi from 20nm out.
Instability of indicators - NO.
Digital VOR navigation bearing display errors up to 5 degrees - NO.
VOR navigation To/From indicator reversal - NO.
VOR and ILS course deviation indicator errors with and without a failure flag - NO.
Reduced sensitivity of the ILS Localiser receiver - NO.
Background noise on audio outputs - YES, although nothing major.
That's purely a response from me in regard to my own aeroplane. I have considerable disdain for bad science, and have tried my level best to prove that any of these assertions hold any water by deliberating dialling my home line to maximise RF activity then shoving the phone as close to these "sensitive" instruments as possible. Nothing... absolutely nothing.
That said, as mentioned above I'm not a scientist and I'll keep them switched off during serious stuff, like flying instrument approaches. They are however very useful on a nice VMC day for calling a taxi from 20nm out.
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Is it possible that you could conduct a test as Shunter has done and find no problems, but change the frequency that the instrument is tuned to and all of a sudden find a problem?
The only problems I've seen were the audio described above, and something interferring with the compass, but can't remember if that was a mobile or something else.
dp
The only problems I've seen were the audio described above, and something interferring with the compass, but can't remember if that was a mobile or something else.
dp
With the ever increasing use of FADEC to control your engine(s), how can you ever be sure that the emi from your mobile phone will not cause the digital electronic controllers to malfunction and power down or fail the engine on your GA aircraft, or even on the heavier metal? I'm sure that it's safe on traditional carb/magneto engines, but modern stuff? There's no knowing what the risk is at present. Better safe than sorry, until they check it all out.
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Nothing in life is guaranteed (except death) but FADEC controls on big jet engines are built and tested to withstand electromagnetic radiation (both radiated and conducted) way in excess of anything that's required in industry.
It is obviously completely impossible (short of a strip search and confiscation) to make sure nobody on board has a mobile phone which is switched on. Or has some other electronic device which is radiating.
That said, I have far less faith in GA electronics than I have in the big stuff. I am an electronics engineer (35+ years' experience) and a lot of stuff that goes on in GA avionics is atrocious. A lot of the stuff is designed by complete muppets.
A friend of mine is on his 4th Aspen EFD1000, in 3 years. The last one died just outside the 1 year warranty so while they have supplied a replacement they have washed their hands of covering the labour. They suggested that there was a thunderstorm in the vicinity of his flight
So, yeah, there is an awful lot of crap out there, in the GA business.
It is obviously completely impossible (short of a strip search and confiscation) to make sure nobody on board has a mobile phone which is switched on. Or has some other electronic device which is radiating.
That said, I have far less faith in GA electronics than I have in the big stuff. I am an electronics engineer (35+ years' experience) and a lot of stuff that goes on in GA avionics is atrocious. A lot of the stuff is designed by complete muppets.
A friend of mine is on his 4th Aspen EFD1000, in 3 years. The last one died just outside the 1 year warranty so while they have supplied a replacement they have washed their hands of covering the labour. They suggested that there was a thunderstorm in the vicinity of his flight
So, yeah, there is an awful lot of crap out there, in the GA business.
If I was flying a Cat III ILS at night, into Zurich, with a 'glass cockpit' I might give this some thought, but I don't think your average, GA, recreational pilot has anything to worry about, enjoy the technology that allows you to call your girl-friend to be waiting for you as you land.
But if a student, don't start texting her before you've raised the flaps after landing - as one of mine did ! If I hadn't thought that I might damage some part of the airframe, I'd have hurled it, and him, out of the cockpit !
Damned phones, what was wrong with Morse Code ?
But if a student, don't start texting her before you've raised the flaps after landing - as one of mine did ! If I hadn't thought that I might damage some part of the airframe, I'd have hurled it, and him, out of the cockpit !
Damned phones, what was wrong with Morse Code ?
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I don't know how any of you guys can hear a damn thing from a mobile phone given the cacophany from the engine in the average light aircraft, nor for that matter, how the person at the other end can make out what you are saying either.
On the rare occasion I indulge ( only if I feel that I might have to ) I plug an earpiece and inline mic. into the thing and tuck the earpiece under my headset into my ear, then tell any caller that I'm flying, can't hear, will call back when I'm down, that usually shuts them up as they can't understand a word, but at least I know that the person I was probably expecting to call did so, and they know that I know and wasn't just ignoring them until such time as I choose to check my 'missed calls' (probably about once a week )
NOTHING ( or very rarely ) is anything that important, and it's only when it might be that I take the phone flying.
NOTHING ( or very rarely ) is anything that important, and it's only when it might be that I take the phone flying.
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I don't know how any of you guys can hear a damn thing from a mobile phone given the cacophany from the engine in the average light aircraft, nor for that matter, how the person at the other end can make out what you are saying either.
But the real issue is that the phone doesn't usually work above about 1000-2000ft.
Occassionally one can send a text message higher than that, and one often receives them much higher (it is normal to find "welcome to xxxx" messages from Belgium, Germany, Austria, Italy, Slovenia, Croatia upon landing following a flight mostly at FL140+). But one can't rely on it.
A satphone is the way to do texts, but then I find a lot of terrestrial networks do not receive them... However one can do short emails with it, which are more reliable. Its best use is for tafs/metars for various airports.
phone technology has moved on,
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Whopity is correct.
However the variable RF output cuts both ways, and aboard an aircraft at say 2000ft the received signal will be very poor, so the phone will wind its power output to maximum.
That's why phone battery life is usually much worse in the countryside
Also, most of the battery life improvements of the last decade or so have been achieved by discontinuous transmission, whereby the transmitter is cycled on/off. This also dramatically reduces the power radiated into one's brain.
They have also stretched out the interval between an inactive phone transmitting to contact the base station(s). It is now IIRC about 10 minutes. So if you have a phone just lying there, it will not radiate anything (of significant power) except for a second or two every 10 mins.
But despite all that, the peak power which a phone can put out is still as high as ever - 400mW I think, though the figure varies according to which frequency it is on (900/1800 etc).
If you want to see if a phone is interfering with avionics, you will need to do it in a low signal area, and actually make a call with it (or receive a call).
Much more common cases of avionics interference are VHF-GPS issues e.g. the 11th or 13th subharmonic of 1575MHz clobbering the GPS receiver. Try transmitting on 121.15MHz or around there and watch the GPS signal levels.
However the variable RF output cuts both ways, and aboard an aircraft at say 2000ft the received signal will be very poor, so the phone will wind its power output to maximum.
That's why phone battery life is usually much worse in the countryside
Also, most of the battery life improvements of the last decade or so have been achieved by discontinuous transmission, whereby the transmitter is cycled on/off. This also dramatically reduces the power radiated into one's brain.
They have also stretched out the interval between an inactive phone transmitting to contact the base station(s). It is now IIRC about 10 minutes. So if you have a phone just lying there, it will not radiate anything (of significant power) except for a second or two every 10 mins.
But despite all that, the peak power which a phone can put out is still as high as ever - 400mW I think, though the figure varies according to which frequency it is on (900/1800 etc).
If you want to see if a phone is interfering with avionics, you will need to do it in a low signal area, and actually make a call with it (or receive a call).
Much more common cases of avionics interference are VHF-GPS issues e.g. the 11th or 13th subharmonic of 1575MHz clobbering the GPS receiver. Try transmitting on 121.15MHz or around there and watch the GPS signal levels.
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Some interesting and useful points made here about this idea of a simple check on the ground for mobile phone interference before using it in the air. From what’s said here my idea of a few simple ground checks in the cockpit is not sufficient on its own. These are a good first step but there are also some general guidelines/principles or perhaps a code of practice for the use of the phone in the air needed as well. This would be to cater for recommendations such as turn the phone off for an ILS approach in IMC, or if tuning into a weak VOR or DME then turn of the mobile to ensure maximum receiver sensitivity, or even students should not text until the aircraft is stationary in case they get thrown out of a moving aircraft by an enraged instructor.
Much more common cases of avionics interference are VHF-GPS issues
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I remember watching a Mythbusters edition where they attempted to test this. You might find this interesting:
Annotated Mythbusters: Episode 49: Cellphones on Planes and Helium Raft
Annotated Mythbusters: Episode 49: Cellphones on Planes and Helium Raft
Let's not overthink this one.
Under VFR, make the call, you can't talk on the radio and on the phone at the same time anyway. I can garantee you that a cellphone does not effect a pitot static instrument such as altitude and airspeed. You can hold heading by looking outside. Make the call, done it numerous times.
The only restriction is your cell phone provider, my current one is not much good above 3000' AGL.
Under IFR ( and IMC) you shouldn't have time to chat on the phone with your buddies anyway
so unless it's an dire emergency I wouldn't do it.
If I have a total electrical failure I'll use my phone since there is nothing left to influence anyways...
Under VFR, make the call, you can't talk on the radio and on the phone at the same time anyway. I can garantee you that a cellphone does not effect a pitot static instrument such as altitude and airspeed. You can hold heading by looking outside. Make the call, done it numerous times.
The only restriction is your cell phone provider, my current one is not much good above 3000' AGL.
Under IFR ( and IMC) you shouldn't have time to chat on the phone with your buddies anyway
so unless it's an dire emergency I wouldn't do it.If I have a total electrical failure I'll use my phone since there is nothing left to influence anyways...
Last edited by B2N2; 27th Sep 2011 at 20:31.