Aids HIV FAQ

Wireless E-mail from the air

Question:

>A scanner is a bad idea. It’s prohibited, so anyone that uses one >(much less boasts about it in newsgroups) is an idiot. Don’t you >agree? >– >Craig

I was once on a Southwest flight (BWI-BDL 1hr flight) where a father and son not only had a scanner out in full view but also were scanning large airmaps. FA’s didn’t even seem to notice. They were having a ton of fun programming in the frequencies and listening around. I sure wasn’t going to point it out as illegal. Matter of fact I peeked back and got a good look at the airmaps with them. -g

Response:

>> so anyone that uses [a scanner] (much less boasts about it in > newsgroups) is an idiot. Don’t you agree? > On airlines where they’re banned, yes.

How about during takeoff and landing on an airline that only allows them in cruise?  I seem to recall JAMORAN claiming that he used his scanner even during those parts of the flight. — Put location information in your DNS! <URL:http://www.ckdhr.com/dns-loc/>

Response:

> I suppose you’ll be trying to have me call an aerial an antenna > next?

The aluminium ones are antennas; the aluminum ones are aerials. miguel — Hit The Road! Photos and tales from around the world: http://travel.u.nu

Response:

> > I suppose you’ll be trying to have me call an aerial an antenna > next? > The aluminium ones are antennas; the aluminum ones are aerials.

Except in Canada.  

Response:

> The main problem with "receivers" is that most of the receivers people > will be using these days will be FM radios… the LO of which can land > squarely in the band used for VOR, or the low edge of the VHF voice comms > range, depending on the tuned frequency.  THat may or may not be the case > also for your laptop, depending on how the clock is generated.  Usually > there is a 66, 100, or 133 MHz bus clock that gets multiplied to the CPU > internal frequency within the CPU chip itself.

Having tested a goodly number of various sorts of PC equipment on an RFI test range, I can pretty much guarantee you that (a) there will be something emitted within the VHF aviation band, and (b) that emission will be at least as strong as the LO emissions from all but the most poorly-designed FM receivers.  The difference is primarily in the internal routing and shielding of the signals; these days, practically any superhet receiver will have a teeny-tiny LO section that is virtually in the same space as the mixer it feeds – little chance for efficient radiation of the signal. >I fully agree that anything that transmits should be prohibited >(including wireless networking cards, which aren’t right now), but >banning receivers is dumb. BTW, I frequently attach a GPS receiver to my >palm just to see where we are, how high we are and how fast we’re going. >A GPS receiver is just a radio receiver (well, with a lot of extra >electronics) and no one seems to have a problem with it. > In fact, the way the FARs in this area are set up, anything the airline > doesn’t say you CAN use, can’t be used.  So according to a strict reading > of the rules, someone DOES have a problem with it.

I’ve known several people with handheld aviation GPS units, who specifically asked the captain for permission to use them in-fligh, and were granted such permission.  In fact, at least one mentioned that the captain on his flight – apparently a gadget buff himself – came back during the flight to see how well the handheld agreed with the cockpit navigational instruments.  There really SHOULDN’T be much of a problem with a GPS receiver, anyway. >So, what part about this makes me an idiot? > I don’t know — maybe you are an expert in the field of EMI, specifically > regarding avionics… and maybe you’ve even gone into the Faraday cage in > your lab, checked your GPS receiver for stray emissions, and found them > below those permitted for the aircraft’s own equipment.  (What would those > levels and frequencies happen to be, by the way?  Do you know?)  If so, > you’d have a much stronger case for your not being an idiot.  It’s > possible.

I’m not the person you were responding to – but while I wouldn’t claim to be an avionics expert, I do have some familiarity with that field, and definitely am familiar with radiated emissions testing as it relates to PCs and associated equipment.  And yes, I’ve even taken a couple of non-PC devices onto the test range, just to see how they did behave.  And that experience leads me to conclude that, if the airlines are nervous about certain pieces of electronic equipment but are happy as clams regarding laptops, palmtops, etc., it’s primarily a CYA approach produced in large part from ignorance. > But even given that, keep in mind that these effects are cumulative.  One > GPS receiver might be just fine, a dozen or so might not be.  I’ll bet > this is why Delta allows scanners (some of which can be tuned to the FM > radio broadcast band) but not AM/FM radios; scanners are pretty rare items > for travelers to carry, and it’s unlikely you’d have more than one on any > one flight; but Walkman-type portables with FM sections are everywhere.

And what’s REALLY funny is that they have no problems with someone using such a Walkman-type portable to listen to a tape while in-flight, even though there is absolutely NO assurance that the LOs are shut down (or that the tape electronics aren’t producing emissions of their own) just because the "radio" section isn’t in use at the time. And it is NOT correct, as a blanket statement, to claim that the effects are necessarily "cumulative"; how many of these radios would be emitting at the same frequency, and even if they were, that the emissions would arrive in-phase at the supposedly affected piece of avionics.  They COULD be cumulative, to be sure – but then, so could a cabin full of laptops.  And again, digital equipment of ANY sort tends to be far "dirtier" than a simple receiver. > Two-way pagers and "Blackberry" units are pretty common too.

Yes, but no one is arguing whether or not it’s a good idea to permit those items which are transmitters by design. > And given > reports like the one I linked to before (where a cabin with a few dozen FM > receivers all tuned to the same station clearly seemed to be affecting the > navigational aids)

The operative word here is "seemed to be".  Until a definitive study is presented, such reports should not be used to argue either way on this issue.  I’m not saying that the report is necessarily incorrect – but I have some reservations about it from a technical perspective. Bob M.

Response:

> >"Aeroplane"?!  Well, that takes us up to about WWI… >What do the airplane makers say about it? > I suppose you’ll be trying to have me call an aerial an antenna > next? > — > Craig

Only if you take a lift up to your flat. Alan

Response:

> >The aeroplane manufacturers have done a great quantity of research >to find (or not find) such a correlation. > "Aeroplane"?!  Well, that takes us up to about WWI… > What do the airplane makers say about it?

Well perhaps if you understood a language other than US English. "Aeroplane" is a proper English word. So, stop criticising, and go watch your colour telly. Michael

Response:

- Hide quoted text — Show quoted text ->Why? I know receivers are prohibited, primarily because they have LOs, >but if you think the 500MHz clock in your PIII isn’t an LO I’ve got news >for you. > The main problem with "receivers" is that most of the receivers people > will be using these days will be FM radios… the LO of which can land > squarely in the band used for VOR, or the low edge of the VHF voice comms > range, depending on the tuned frequency.  THat may or may not be the case > also for your laptop, depending on how the clock is generated.  Usually > there is a 66, 100, or 133 MHz bus clock that gets multiplied to the CPU > internal frequency within the CPU chip itself. >I fully agree that anything that transmits should be prohibited >(including wireless networking cards, which aren’t right now), but >banning receivers is dumb. BTW, I frequently attach a GPS receiver to my >palm just to see where we are, how high we are and how fast we’re going. >A GPS receiver is just a radio receiver (well, with a lot of extra >electronics) and no one seems to have a problem with it. > In fact, the way the FARs in this area are set up, anything the airline > doesn’t say you CAN use, can’t be used.  So according to a strict reading > of the rules, someone DOES have a problem with it. >So, what part about this makes me an idiot? > I don’t know — maybe you are an expert in the field of EMI, specifically > regarding avionics… and maybe you’ve even gone into the Faraday cage in > your lab, checked your GPS receiver for stray emissions, and found them > below those permitted for the aircraft’s own equipment.  (What would those > levels and frequencies happen to be, by the way?  Do you know?)  If so, > you’d have a much stronger case for your not being an idiot.  It’s > possible. > But even given that, keep in mind that these effects are cumulative.  One > GPS receiver might be just fine, a dozen or so might not be.  I’ll bet > this is why Delta allows scanners (some of which can be tuned to the FM > radio broadcast band) but not AM/FM radios; scanners are pretty rare items > for travelers to carry, and it’s unlikely you’d have more than one on any > one flight; but Walkman-type portables with FM sections are everywhere. > Two-way pagers and "Blackberry" units are pretty common too.  And given > reports like the one I linked to before (where a cabin with a few dozen FM > receivers all tuned to the same station clearly seemed to be affecting the > navigational aids) I really don’t want a bunch of less-tech-aware folks > noticing you with your GPS unit and deciding to follow your example with > their Walkthings.  Sometimes, a little bit of knowledge is dangerous… so > much so that we have an obligation to keep it from those who would try to > use it in areas where it doesn’t apply. >         — jeh

Jamie, You raise some very good points, especially with regards to "setting an example." I hadn’t thought of the cumulative effects of multiple receivers, and it makes sense that these could cause problems. In regards to the GPS receiver, I wouldn’t consider myself an expert in EMI, but I am pretty knowledgeable. Just for fun, I had a look at the EMI emissions from my Palm Vx both with and without the GPS receiver and found that the spectra looked pretty much the same (I consult for a wireless telecom company and have access to their facilities). Still, it’s probably best not to play with toys like that in flight for the other reasons you mention. Alan

Response:

>The aeroplane manufacturers have done a great quantity of research >to find (or not find) such a correlation.

"Aeroplane"?!  Well, that takes us up to about WWI… What do the airplane makers say about it? Our Craig–always giving us good setup lines…

Response:

>Why? I know receivers are prohibited, primarily because they have LOs, >but if you think the 500MHz clock in your PIII isn’t an LO I’ve got news >for you.

The main problem with "receivers" is that most of the receivers people will be using these days will be FM radios… the LO of which can land squarely in the band used for VOR, or the low edge of the VHF voice comms range, depending on the tuned frequency.  THat may or may not be the case also for your laptop, depending on how the clock is generated.  Usually there is a 66, 100, or 133 MHz bus clock that gets multiplied to the CPU internal frequency within the CPU chip itself. >I fully agree that anything that transmits should be prohibited >(including wireless networking cards, which aren’t right now), but >banning receivers is dumb. BTW, I frequently attach a GPS receiver to my >palm just to see where we are, how high we are and how fast we’re going. >A GPS receiver is just a radio receiver (well, with a lot of extra >electronics) and no one seems to have a problem with it.

In fact, the way the FARs in this area are set up, anything the airline doesn’t say you CAN use, can’t be used.  So according to a strict reading of the rules, someone DOES have a problem with it.   >So, what part about this makes me an idiot?

I don’t know — maybe you are an expert in the field of EMI, specifically regarding avionics… and maybe you’ve even gone into the Faraday cage in your lab, checked your GPS receiver for stray emissions, and found them below those permitted for the aircraft’s own equipment.  (What would those levels and frequencies happen to be, by the way?  Do you know?)  If so, you’d have a much stronger case for your not being an idiot.  It’s possible.   But even given that, keep in mind that these effects are cumulative.  One GPS receiver might be just fine, a dozen or so might not be.  I’ll bet this is why Delta allows scanners (some of which can be tuned to the FM radio broadcast band) but not AM/FM radios; scanners are pretty rare items for travelers to carry, and it’s unlikely you’d have more than one on any one flight; but Walkman-type portables with FM sections are everywhere.   Two-way pagers and "Blackberry" units are pretty common too.  And given reports like the one I linked to before (where a cabin with a few dozen FM receivers all tuned to the same station clearly seemed to be affecting the navigational aids) I really don’t want a bunch of less-tech-aware folks noticing you with your GPS unit and deciding to follow your example with their Walkthings.  Sometimes, a little bit of knowledge is dangerous… so much so that we have an obligation to keep it from those who would try to use it in areas where it doesn’t apply.           — jeh

Response:

>>Not that the scanner is necessarily a great idea – it would >depend on the level of spurious emissions from its local >oscillator(s), but it is without a doubt a FAR lower risk to >the avionics than a transmitter. >A scanner is a bad idea. It’s prohibited,

Well, that depends on the airline.  Delta specifically allows scanners (but mentions am/fm radios in their "banned" list).  US Airways doesn’t include scanners (or am/fm radios either) in their banned list, though they do ban TV sets. >so anyone that uses one >(much less boasts about it in newsgroups) is an idiot. Don’t you >agree?

On airlines where they’re banned, yes.         — jeh

Response:

Why? I know receivers are prohibited, primarily because they have LOs, but if you think the 500MHz clock in your PIII isn’t an LO I’ve got news for you. I fully agree that anything that transmits should be prohibited (including wireless networking cards, which aren’t right now), but banning receivers is dumb. BTW, I frequently attach a GPS receiver to my palm just to see where we are, how high we are and how fast we’re going. A GPS receiver is just a radio receiver (well, with a lot of extra electronics) and no one seems to have a problem with it. So, what part about this makes me an idiot? Alan – Hide quoted text — Show quoted text ->Not that the scanner is necessarily a great idea – it would >depend on the level of spurious emissions from its local >oscillator(s), but it is without a doubt a FAR lower risk to >the avionics than a transmitter. > A scanner is a bad idea. It’s prohibited, so anyone that uses one > (much less boasts about it in newsgroups) is an idiot. Don’t you > agree? > — > Craig

Response:

> Much like that idiot John Moran, who used to boast in this forum > that he regularly used his scanner on scheduled flights.

There’s a very significant difference between using a scanner (or other receiver) and using a device which contains a transmitter (such as a cell phone or "wireless e-mail" device). Not that the scanner is necessarily a great idea – it would depend on the level of spurious emissions from its local oscillator(s), but it is without a doubt a FAR lower risk to the avionics than a transmitter. Bob M.

Response:

>  I don’t think anyone has done any research to determine if cell phones and > e-mail really effect avionics.

And you’re wrong. Electromagnetic interference tests have been and are being done. Not so much on the effect of "e-mail" on avionics, for sure. But definitely on the effect of high-frequency electromagnetic emissions. > The signals for aircraft are so strong that it > is highly unlikely that these devices will effect aircraft signals.

The question is not whether there will be interference with ATC communications, if that is what you are referring to. The question is whether the onboard electronics are effected. > Please, if you disagree with this  cite specific studies and where to find > them, otherwise, keep quiet.

Perhaps you should first cite anything that substantiates your assertions. As for who is allowed to post here and on what topic, that is not for you to decide.

Response:

> What I disagree with is that you, or the self-centered fool quoted above, > or I for that matter, have enough information and knowledge to accurately > evaluate the risk and the effect it has on the overall risk of flying… > let alone the right to impose that evaluation on the other souls aboard > without their informed consent.  The risk may indeed be very very low — > but as with a game of Russian Roulette, it’s not a bet I can afford to > lose; it certainly isn’t a bet that I should be forcing others to make > without their even knowing it.  

I agree that this is the significant issue. Given that it MIGHT be dangerous to a whole planeload of people, anyone without specific scientific knowledge to the contrary who nevertheless uses such a device for their own convenience is sitting somewhere between despicable and evil. miguel — Hit The Road! Photos and tales from around the world: http://travel.u.nu

Response:

> Please, if you disagree with this  cite specific studies and where to find > them, otherwise, keep quiet.

I don’t disagree that there is no evidence they are dangerous. However, they have not been ruled as safe. And.. these people should be aware of the fact that they could be penalized for the activity.

Response:

– Hide quoted text — Show quoted text – > "I know you’re not supposed to do it, but it’s > easy and it works." She said she keeps her device on for only a minute > or two, and thus does not think she is causing a safety problem. > [Comments anyone?? > -tw] >How many minutes does it take to screw up an airplane??>> > I don’t think anyone has done any research to determine if cell phones and >e-mail really effect avionics.

You’re kidding, right?  You seriously believe that none of:  the aircraft manufacturers, the avionics contractors, the FAA, the airlines… have ever or would ever have conducted such tests?   See, for example, http://www.boeing.com/commercial/aeromagazine/aero_10/interfere.pdf >The signals for aircraft are so strong that it >is highly unlikely that these devices will effect aircraft signals.

Wrong.  The strength of the signals received from the ground — AT THE AIRCRAFT’S ANTENNAE — is FAR less than those picked up from mobile phones and two-way pagers within the cabin.  Sure, the ground transmitters are much more powerful, but they’re also much farther away.  Inverse square law and all that.   The document mentioned above does not cite specific power levels.  It does state that the emissions they measured from a various PEDs were, as stated for one study involving cellphones, "generally within airplane equipment emission limits", meaning that the PEDs radiated no more junk than the airplane’s own equipment is allowed to.  But there are exceptions. Cellphones, for example, were measured radiating more than 60 dB above the airplane equipment limits at the phones’ operating frequencies.   This isn’t unexpected; mobile phones (like Blackberries and other two-way pagers) do include radio transmitters, and any transmitter’s output is going to be FAR higher than the spurious emissions from most anything not intended to be a transmitter; it wouldn’t be much good as a transmitter if that weren’t the case.  The reason cellphones and Blackberries don’t instantly jam the airplane’s receivers is that their operating frequencies are many hundreds of megaHertz away from most of the airplane’s radio comms.   But that’s not an ironclad guarantee.  For that to work out, it assumes that everything in the airplane’s receivers is working correctly.  Ask any knowledgeable ham operator about "receiver desensitization" sometime — it’s a phenomenon whereby a nearby transmitter can essentially shut down your receiver, making it insensitive to the signals you want to hear, even though the transmitter is on wildly different freqs than what you’re tuned to.  Of course aircraft receivers are designed to avoid this problem, but guess what — the design elements in question can go bad.  And when they do, the problems don’t often show up under any other scenario; in the absence of a nearby transmitter, the radio works just fine… so no one will notice the problem until, well, it’s a real problem.   >Please, if you disagree with this  cite specific studies and where to find >them,

Although you’re wrong about the signal strengths, I don’t necessarily disagree with your evaluation of the risk as "highly unlikely."   In fact the Boeing document cites many studies in which they found no ill effects. What I disagree with is that you, or the self-centered fool quoted above, or I for that matter, have enough information and knowledge to accurately evaluate the risk and the effect it has on the overall risk of flying… let alone the right to impose that evaluation on the other souls aboard without their informed consent.  The risk may indeed be very very low — but as with a game of Russian Roulette, it’s not a bet I can afford to lose; it certainly isn’t a bet that I should be forcing others to make without their even knowing it.   Here’s another relevant article with some good accurate tech info: http://amulation.com/md-l-archive/199708/msg00020.html > otherwise, keep quiet.

You’re kidding, right?  You expect that to work?         — jeh

Response:

 "I know you’re not supposed to do it, but it’s > easy and it works." She said she keeps her device on for only a minute > or two, and thus does not think she is causing a safety problem. > [Comments anyone?? > -tw] >How many minutes does it take to screw up an airplane??>>

 I don’t think anyone has done any research to determine if cell phones and e-mail really effect avionics. The signals for aircraft are so strong that it is highly unlikely that these devices will effect aircraft signals. Please, if you disagree with this  cite specific studies and where to find them, otherwise, keep quiet.

Response:

 "I know you’re not supposed to do it, but it’s > easy and it works." She said she keeps her device on for only a minute > or two, and thus does not think she is causing a safety problem. > [Comments anyone?? > -tw]

How many minutes does it take to screw up an airplane??

Response:

E-mail from the air: Washington Post Sept 5, 2001 Page E01 When several Washington area commercial real estate brokers are on a flight, they’ve discovered they can still communicate with each other and their clients via e-mail, thanks to their Blackberry wireless, hand-held device. One traveler, who obviously doesn’t want to be identified, said his colleagues hold their Blackberry devices up to the window during flights and are able to collect and send e-mail as if they were in their offices. "Flying from here to San Francisco, we’re no longer out of touch with each other as long as we have a window seat," he joked. The Blackberry devices are strong enough to receive and send e-mail 30,000 feet in the air, according to these travelers. Of course this is against the airlines’ rules, since all two-way communication devices such as cell phones and pagers must be turned off, for fear of interfering with the airline’s navigation system. And Blackberry executives discourage using the devices during flights. In fact, Blackberry created an airplane icon that users are supposed to click to disable the wireless component during flights. "We want people to follow the airlines’ guidelines," said Mark Guibert, vice president of brand management for Research in Motion, Blackberry’s parent company. Guibert said he has seen fliers typing into their hand-held devices. But he said they were only writing e-mail and storing it until their plane landed. One traveler — an executive of a Washington-based, nonprofit group — said she never turns her Blackberry off. Because she links her Blackberry to her office desktop computer to read her corporate e-mail, she no longer carries a laptop on business trips. Furthermore, she said she doesn’t have to hold her Blackberry up to a window to get it to receive and send e-mail. "I’ve done it from the aisle or middle seat. I’ve never not been able to get a signal," she said. "I know you’re not supposed to do it, but it’s easy and it works." She said she keeps her device on for only a minute or two, and thus does not think she is causing a safety problem. [Comments anyone?? -tw]

Response:

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