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Cell Phone Usage on Airplanes == Bad Idea
gclef writes "The New Scientist is reporting on a study done by the UK's Civil Aviation Authority that shows that older planes can't handle cell phone emissions. Hackernews has a little commentary on this as well. Good to hear that the newer planes can handle this, but why the heck were older planes *not* build with Faraday cages and shielded wires? Scary...." Look a ways down the page for the HNN piece - but at least now I know that this isn't simply one of the arbitrary rules that the airlines setup.
well, GPS approach is becoming more widespread (Truckee-Tahoe even has one, and they don't have a tower!) and ILS isn't used as much. only /slight/ problem with this is that GPS approaches tend to be locked into the flight computer and done automagically (well, this is how it's set up in our 414, anyways), which makes it even MORE of a problem if there's interference.
...) as well as the use of GPS approaches, I'd guess that they're shielded with this sort of thing in mind)
do you know if GPS is as suceptable to this sort of interference? (given the flight-charts-on-the-laptop (not to mention civ:ctp on the other laptop, or the TV, or the VCR,
Lea
There was an article in the WSJ a while back about the whole air cellular thing. It covered the FCC vs. FAA regulation, the lack of any evidence ever of a cell phone or computer interfering with a plane, etc.
One thing they mentioned is that those egregiously expensive AirFones are just cell phones with the base stations farther apart. For that we pay 10-20x higher fees.
However if there is some heretofore undiscovered interference found, then we logically should refuse to fly on airlines with AirFones, no?
Let's all stand by and watch while each airplane is grounded for re-testing. Until that happens I'll take this with a grain of salt.
---- "If we have to go on with these damned quantum jumps, then I'm sorry that I ever got involved" - Erwin Schrodinger
I hate cell phones in total. No one has even proven they are safe, except for the "tests" the cell phone companies have run, which by the way are not sufficient, and just a tidbit to leave you thinking about. While nothing has shown that cell phones CAUSE cancer (yet), cell-phone users that got brain tumours/cancer/whatever have a tendency to get the disease on the same side of the head they hold their cell-phone on, and there are quite a few cases where the tumour was in the shape of the cell phone, exactly where they usually hold it! Think about it. Is it worth the risk?
"As many of you know, I was very instrumental in the founding of the Internet" --Al Gore to Katie Couric 3/99
I'm reluctant to admit to such a flagrant act of nerdiness, but, here goes:
My last airline flight happened about a month ago. I thought it would be neat to take my new portable hand-held shortwave radio with me on the plane to see if I could pick up the transponder on the aircraft's black box(es), or maybe some of the cockpit/tower discussion. The flight was pretty much empty (I always take the red-eye) so for about an hour, I sat there with my earphones on and my antenna pitched up and scanned the whole damn plane from 1 Mhz all the way up to about 400 Mhz or so in short, medium, longwave and FM.
I didn't find anything recognizable. I was seated far enough away from the engines to rule out any interference, and the whole spectrum was peppered with odd little noises generated by the aircraft (This was a Boeing 767-300 if I remember correctly) but nothing resembling any sort of communications. Considering the fact I was seated in a giant metal tube, I can also rule out ambient interference. There was a guy with a laptop about 10 rows up, and I could pick up his machine pretty easilly. Anyway, no luck.
Most analog cell phone transmissions occur between 800 and 950 MHz. Youre going to have a hard time finding a scanner than will allow you to listen to that range. If I remember correctly, there was a law passed in '93 or so which made it illegal to sell scanners with capability in that range, in order to protect the privacy of analog cell phone users.
You wouldn't believe the stuff I heard. People's conversations get sorta...weird after 9PM. It's a sick world.
Bowie
PS.. No "You didn't hear anything in the cockpit because the crew was asleep" jokes, please.
Bowie J. Poag
Bowie J. Poag
One of the first things they teach you in flight school is that interference caused by cell-phones can cause navigational radio instruments such as the VOR and ADF to go haywire or be a little off...
Actually, most of the cost of aircraft-certified *anything* is in the form of "prepaid liability". Whether its commercial or private, the lawyers will go after every manufacturer of every component in an aircraft in search of deep pockets in the aftermath of an accident.
--
Well, I've always thought that cell phone usage in cars is a bad idea, but on airplanes?? Pilots should certainly not be allowed to use cell phones.
The evaluation of an action as 'practical' . . . depends on what it is that one wishes to practice.
Wow
Eh...
Nice idea, but I don't think so.
If a technological solution is decided on, it means either every aircraft used for MPT (Mass Public Transport) or every cell phone will need to have something done to it. Neither is going to happen.
Which is why there needs to be a legal solution. After the first few people get locked up/fined large sums of money, the public will get to know the airlines mean business.
Dunno about "a study," but there are laptops certified for use on board commercial/passenger aircraft. (As I recall, it's a combination FCC/FAA thing: the FAA says "if it meets FCC code such-and-such, it's okay.") I know, because my former employer had to buy some for cockpit use.
However, the POI for that airline still has to sign off on that particular model, etc., so it isn't as if you can walk on, as a passenger, and say "See the sticker? This meets code!" and expect to be able to use it.
Of course, one laptop manufacturer cheerfully explained that although all of their laptops would meet code, they only had the rugged-built (and, more to the point, expensive) models actually certified as such.
Slashdot's token middle-aged housewife
--
Actually, lots of people use a cellphone close to two hours a day (not me, I still refuse to get one - I have a CB (and a flare gun) in my car for emergencies, that's good enough). Think of the sales and marketing types who are running around, travelling, etc... The company picks up the bill for that phone, and it's more mobile than the one in the hotel room anyway. Waiting for a meeting - 5-10 quick minutes. Family calls you... etc. And now there's those ad campaign pushes to "Make your mobile phone your only phone".
I think it's alright - generally, the people who use mobile phones the most are the least likely to be missed if they all dissapeared. I just hope they don't take me out on the road (cellphone + driving = LOOK THE ext2fsck OUT!!!).
"It's tough to be bilingual when you get hit in the head."
Yes, I believe they will tell us that Pepsi causes cancer in a few years....
Because the data about the problems has been mainly unscientific. The number of variables envolved in this is really large, ie location of the passenger in the aircraft, type of phone, location of aircraft, type of aircraft, weather conditions. It's widely accepted by pilots that these things do cause problems.
:-)
I know of a pilot who was experiancing problems which seemed to be from RF emissions from something, and suspected a mobile phone. So he had the stewards do a walkthrough of the plane and see if anyone was suing a mobile phone/computer. They didn't find anyone, and the interference continued. So he tuned the radio in cockpit to the frequency used by analog mobile phones and hey presto... "*ring*ring* Hello?" "Hi, this is James Smith calling about my appointment..". So he checked the passenger manifest, found this person's seat and asked "Can I have a look at your mobile phone?". The guy handed it over, pilot said thanks and handed back the phone, sans battery. The person had been delibrately hiding the phone when they were searching the plane.
Idiots abound in the body of an aircraft
What would happen if about 100 hackers all got some old cellphones, rigged them to some of the key frequency, and all powered up and used them at the same time?
... your seat cushions could be used to keep the sharks happy!
Wouldn't that be cool?
Talk about surfing
Will in Seattle
I think Pepsi One can actually cause cancer in a matter of days. Maybe not, but tasting that crap is just as bad as cancer.
MacSlash: News for Mac Geeks
A common mistake, but perhaps you meant "==" instead of "=" ;-)
Patch below.
-core
--- slashdot_article_orig.txt Mon Jun 12 14:11:29 2000
+++ slashdot_article_new.txt Mon Jun 12 14:11:47 2000
@@ -1 +1 @@
-Cell Phone Usage on Airplaces = Bad Idea
+Cell Phone Usage on Airplaces == Bad Idea
Assume for a moment that we don't have to deal with corrupt politicians appointed to head the appropriate government agency (FAA to do the actual orders, FCC to provide technical backup, CIA/NSA/DIA/FBI to provide some ideas about terrorists using this for a weapon like SheldonYoung said) or the industries with a vested interest in maintianing the status-quo (lawyers, mainly). The only problem then is creating a quality solution, testing it, and implementing it.
Let's say that we have most of a quality solution already, what with the newer planes having Faraday cages and shielding, we only need to do a little more work on the design, call it a month. Then the 'solutions' must be tested in a lab, say 3-6 months depending on problems and facilities. After that there must be tests on real airplanes. First you put cell phones, PDAs, walkmen, CD players, computers, cell modems, CBs, and what-not in a test plane (a plane with no passengers) and a flight crew of test pilots. After a statistically significant set of tests in these somewhat controled conditions, the tests are expanded to a few real flights with special test flight crews. These tests are the first with real conditions: read RISK OF DEATH of the flying public.
I am not trying to troll or exagerate, but when you risk loss of control of an airplane, at any altitude, you risk the death of all aboard. There are usually ways to reduce risk, such as putting fly-by-wire controls in aircraft which use hydraulics, letting you switch from the wired controls to the hydraulics if the electronics go kaput when the cell phones are turned on. Eventually, you need to install the safety systems on aircraft which do not have non-electronic backups. This is the most risky step in the progression from idea to routine use; the design has been tried & tested, but there may still be a few tiny problems. Unfortunately, 'tiny' is usually easy to fix, but deadly until fixed.
All of this means that fixes are not easy to do. However, fixes should be made. Why the FAA hasn't mandated safety devices on all airliners is unknown to me (I could guess, but ... ), but it should start a program to get a quality fix in place as soon as possible. The quality fix will be able to handle all of the current frequency and power ranges, and those which might be used in the future.
In short, for the FAA ' ... to dump those "RF on an airplane" rules, and mandate a technological solution.' is not easy to do, and it can not be done quickly for fear of loss of life.
Louis Wu
Thinking is one of hardest types of work.
...would a cellular phone one mile up cover thousands of cells?
Maybe someone could post something about that. ;-)
------
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You are in a twisty little maze of open source licenses, all different.
Aircraft navigational systems vary in frequencies
:>
and sensitivity. The real headache here could be
for a category IIIa ILS approach. The localizer will use something in the 108-114Mhz range, but
the glideslope is UHF.
Instruments like the ADF are sensitive to any
strong (And some weak) electronic signal, and will
swing to point to the strongest source of RF
emissions that pass its filters. Won't necessarily
be a cellphone, but you never know.
For me, a more convincing reason never to use
Cellular phones, or allow any passenger of mine
to do so would be:
As per FAR (15 CFR) 121.305:
(a) Except as provided in paragraph (b) of this section, no person may operate, nor may any operator or pilot in command of an aircraft
allow the operation of, any portable electronic device on any U.S.-registered civil
aircraft operating under this part.
(b) Paragraph (a) of this section does not apply to--
(1) Portable voice recorders;
(2) Hearing aids;
(3) Heart pacemakers;
(4) Electric shavers; or
(5) Any other portable electronic device that the part 119 certificate holder has determined will not cause interference with the navigation or communication system of the aircraft on which it is to be used.
And per 91.21:
(a) Except as provided in paragraph (b) of this section, no person mayoperate, nor may any operator or pilot in command of an aircraft allow
the operation of, any portable electronic device on any of the following U.S.- registered civil aircraft:
(1) Aircraft operated by a holder of an air carrier operating certificate or an operating certificate; or
(2) Any other aircraft while it is operated under IFR.
(b) Paragraph (a) of this section does not apply to--
(1) Portable voice recorders;
(2) Hearing aids;
(3) Heart pacemakers;
(4) Electric shavers; or
(5) Any other portable electronic device that the operator of the aircraft has determined will not cause interference with the
navigation or communication system of the aircraft on which it is to be used.
(c) In the case of an aircraft operated by a holder of an air carrier operating certificate or an operating certificate, the determination
required by paragraph (b)(5) of this section shall be made by that operator of the aircraft on which the particular device is to be used.
In the case of other aircraft, the determination may be made by the
pilot in command or other operator of the aircraft.
Or.. whatever.
--=:: Wings and tail and snout and scales of blackest night
Its not an issue of if its bad for the aircraft, Trust me on that, 10 Years in the military as a aviation electronic tech. Cell phones don't put out enough power to be a problem, what does happen is they are "Line of sight" transmitters and receivers, when you are on the ground and use a cell phone it talk's to 4 or 5 towers to figure out who has the best strength, when you are in the air its thousands of towers, all those towers talk to each other and so forth, all to figure out who has you the best. To the guy in the air it's a one second delay but to the people on the ground it could be a lot more. My two cents.....
p = transmitter power
d = distance
s = power flux density
s = p / (4 * Pi * d^2)
Mea navis aericumbens anguillis abundat
shouldn't it be "airplanes"?
si hoc legere scis nimium eruditionis habes
Check it out here
--buddy
...on a plane (after takeoff) and I've never been able to get any service. I have a feeling results would be very poor even if allowed.
--- Speaking only for myself,
but they didn't.
"Stop whining!" - Arnold, as Mr. Kimble
is that kind of like people trying to look cool and destroying their lungs and giving themselves cancer by smoking?
si hoc legere scis nimium eruditionis habes
Correct. Also, the FCC's definition of 'cellular telephone' only includes phones than transmit on the original cellular frequencies of 800mhz.
Newer 1900mhz phones are not covered by this regulation. (however an airline can still require that you not use them.) I'm a private pilot, and have used my 1900mhz PCS phone on a few occasions from the air in a Cessna 172. I've found it can be difficult to get a good signal however.
Now I assume cell phones use Collision Detection networking methods, hence the more phones the noiser the airwaves get. If we reduce this to a few, it's less dangerous, hopefully to the point of being almost 100 percent safe..
And as someone else said. The nice guy sitting up top/in front in the left hand seat has done a lot of training to be there. He knows his plane VERY well. If he isn't sure about you using your cell phone, I don't think it's worth the risk..
I have read an article (from Finnish magazine) that real reason to avoid Cell Phones on aeroplanes is that basestations on ground can't handle cellular phones on air.
If you are flying high enough, your phone receives too many signals and it can't handle that. Also many basestations are using same frequencies in different locations and on air you receive many of those same time.
Also basestations can't follow your phone if you fly fast enough. Cell phone selects always best basestation which signal strenght is highest. And on aeroplane signal strenght varies a lot.
[ Advertizing Banner Here ] dUb(at)lumi'dyndns'org
Uhm, because people will quite often talk a lot louder into a cell phone than they will to a person who is sitting next to them (he says rather sheepishly).
--
Free Software: Like love, it grows best when given away.
All electronic devices create interference, but I thought that problems in using a cell phone were caused by a system that get's confused by a ambiguosus position in relation more than one close ground stations. Live and Learn. And the smoking restriction wasn't caused by the reduction of costs in air conditionina, no, it was the the wealth of costumers.
Two reasons:
1) People talk more loudly on the phone than face-to-face. This is partly an unconscious reaction to the lack of non-verbal commmunication, and partly due to the fact that it's difficult to hear what's being said for both parties to the conversation.
2) There's nothing more frustrating than hearing half a conversation.
Holy crap. If that's what cellphones do to you, I'm handing mine back!
No boom today. Boom tomorrow. Always boom tomorrow. BOOM!
If you want to get an idea of HOW BAD a portable device can emit interferrance, find a cheap TI calculator (you know, the one's kids these days use in the 5th grade).
Turn it on.
Set it next to a cheap radio receiver. Turn on the AM band. Flip around the dial until you hear a wierd regular pattern. Play with the calculator. Notice how the pattern changes as you play with it.
This is a cheap calculator with a "processor" less powerfull than an 8088. Being powered by a watch battery.
Do you honestly think that your laptop -- with it's lithium ion batteries powering a Pentium III/500, hard drive spinning at 7200 rpm, multiple fans, LCD screen with fleurescent backlight -- produces LESS noise than a freek'in calculator? Yeah, they're shielded; but the shielding isn't THAT good, just enough to keep it from interferring too much with your portable phone.
(shoot, if you knew how much noise an electic motor alone made you wouldn't bring up that question...Electric RC cars have severe problems with noise from the motor if a few things arn't done to mitigate the problem [add a few capacitors in spots to eat up the sparks, basically]).
False.
FM modulation results in "signal capture" i.e. the strongest signal gets through. With AM what you get is "heterodyning" [look it up] which results in an annoying squeal for everyone listening on that frequency.
Pilots know this very well, since ATC communications are AM. Every now and then two people will speak together (referred to as "stepping on someone else") followed by someone saying "Blocked" or similar.
AM is bad for blocking interference also. You can hear thunderstorms on AM radio.
A very common problem with electronics close to each other is the front-end of a receiver getting overloaded by a strong RF signal. With a mobile phone this is unlikely but possible - and as someone else said, aircraft radios were never certified against mobile phones and their frequencies.
Unlimited growth == Cancer.
an article from the Wall Street Journal at junkscience.com. I like the last paragraph of the article that says: "Car accidents resulting from using a cell phone while driving are 'much more of a problem at this point' than radio emissions".
Another good one from junkscience.com
"There is no shot you can take that I cannot simply deny." - Ertai, wizard goalie
Even though you weren't transmitting with your radio, it could have interfered with airline electronics. That's why portable radios are not allowed to be used _at all_ on flights--they are banned by the FAA. IIRC, they have various oscillators that can interfere with many frequencies directly and many indirectly through harmonics.
An old IEEE article in Spectrum from a couple years ago discussed this.
-core
TomV
Again, I do not speak for my company
AFAIK, GPS navigation is not really widespread. None of our aircraft have it.
GPS naviagation requires a correction signal transmitted from the ground to the air to compensate for GPS error (both artificial and natural error). The idea is to survey the exact location of the end of the runway and install a GPS receiver that listens to the GPS signals and transmits GPS error compensation data.
GPS Navigation will never replace existing methods. Nor should it - redundency in navagation data is good. Of course, if the data do disagree, which version of the truth do you want to go with. Until somebody dies and the NTSB concludes GPS would have prevented it, it isn't likely to be mandatory.
Commercial aviation tends to be highly regulated and the FAA inspectors tend to be reluctant to allow airlines to change procedures and processes when the operating carriers have good safety records. Everything in flight is scripted.
What will put GPS in commercial aircraft is something called "Free Flight". Aircraft don't flight straight from point A to point B. They follow a connect-the-dots route with NavAides every one to three hundred miles. These form highways in the sky. Free Flight will allow aircraft to "Off Road." With a proposed implementation arround 2006, this will take a while.
Another impediment is there are many carriers with aircraft fleets older than the average Slashdot reader. (FYI - not mine.) There isn't anything to plug a GPS into.
Cheers!
This is a boring sig
Why is driving while talking on a cellphone dangerous? Is it because it involves the concentration of listening and talking? In that case, why do you not also complain about people talking to their passengers? Or is it because it occupies a hand? Why then do you not complain about people who only have one hand who drive?
El Al, widely regarded as having the tightest security of any carrier provides some insight here. Bags are checked by machine for every passenger and by hand for many. In addition, some unsmiling individuals will ask you a series of questions about your luggage. And yes, they are adequately trained for this...don't even think about lying. It's scary and it's effective. Doubtless there are other technological measures in place behind these scenes--rucksacks are tamper-sealed once checked, for a start. But it's the quality of the questioning that's key to security.
When I was 11, I went with my family to Israel. The security guy asked my father if we'd ever been before. I piped up "no", not remembering that we'd been as a toddler. Not only did I get a look that stopped me from saying anything else till we were ground-side in Israel, but we were also delayed for 20 minutes while they checked things out more thoroughly.
The human factor is the key factor. There are rumours that background checks are carried out on every passenger on an El Al plane (including the ultra-Orthodox guys with the beards and black hats) before you fly and that there are security agents on every El Al plane (in plane clothes) and all over the airports. It's certainly true that they have no qualms about letting you miss your plane in order to question you more thoroughly.
Is it painful? Yes. Does it cost El Al a fortune? You bet. Do you feel secure flying with them? Yes indeed.
[Side note: I flew with BA to Israel not so long ago. The same unfriendly faces were asking the same questions -- so it's likely that at least half the security measures are required / implemented by the government and not El Al.]
Localizers use frequencies around 110 MHz. Consumer FM receivers use a first intermediate frequency (IF) of 10.7 MHz. What this means is that if you tune an FM radio to KOZY 101, the radio transmits noise at 101.1 + 10.7 = 111.8 - which is bang in the middle of the navigation band.
Inertial is not used for approaches, only for en-route navigation. The problem with inertial systems is that they drift, so the longer you've been airborne, the more inaccurate they are. An error of about a mile is no problem up in the stratosphere, but you can't be a mile off the runway when you touch down...Right now ILS is the only precision approach available in the vast majority of cases. Once the FAA puts up WAAS and LAAS augmentation for GPS, aircraft can use GPS for precision approaches.
Unlimited growth == Cancer.
). The VHF aeronatutical band is just below the commercial FM band, by the way.
ObNitpick -- it's above the FM band.
Banned in all the hospitals i've been in here in Australia for some time. Mind you, we're way ahead with that sort of thing.. had GSM for well over about 13 years now. They're not strict about the appliances on airplanes so much here.. mobile phones and radios are a no-no, but anything else is fair game. Interestingly enough tho, we've got the best safety record (even including Qantas' efforts in the last month or two) as far as airline safety is concerned. Mind you, every time i've heard/seen someone on a mobile phone in a plane, they've been talking with that all too familiar yankee accent. Coincidence? Oh, and talking on a mobile phone without a hands free kit in a car is illegal and has been for some time. When people obey laws such as that one, things actually are safer.. maybe some of you whinging yanks should try it sometime :)
So, you've got an O:Line? That dont impress me much du du da du.
If you've ever taken a physics course, you would know that electricity will travel the surface of a metal cylinder instead of going through it. Most EM radation (maybe all) does the same thing.
Now, getting HIT by a lightning bolt should do the same thing, but lightning is so powerful that it can actually melt the metal and go through it...(though for the most part it seems to leave a char mark on two sides of a wing while not actually going through it).
In addition to the other post, the electic motor present in the cd player also generates noise.
I've pondered this situation and the conclusion that I've come to is that noone should get into the right lane, everyone should fill all the lanes right up to the restriction. It wouldn't help traffic flow any faster, things would still get blocked off but at least it would be an equitable slow down and wouldn't benefit those arrogant arseholes who think their time is somehow more important than other peoples. Better that they cause incovenience to everyone rather than everyone else
And just for the record, even when I used to drive fast like a madman, I used to get in the correct lane since it seemed clear to me that if everyone just did the same, everyone could sail through at a decent cruising speed. My, how naive I was. Mind you, it's the people that let these pricks in that are as much to blame. It would be nice if the cops would do something about it too. There's rules about "due care and attention" in this country.
Rich
Yes. Your walkman has an electric motor in it. Electic motors are VERY noisy.
If you want to see the effect of your 'little' hp48, go to wallmart and buy a cheap TI calculator. Turn it on next to a cheap radio. Play with the radio frequencies in the AM band until you hear your calculator. Yes, you will hear that cheap TI add/subtract/multiply/divide calculator. Powered by a watch battery.
Now consider that the hp48 has a processor running at a much greater speed, by more batteries that last for less time and has actual (noisy) electronics in it and tell me if you still can't figure out why it could be a problem.
There are all sorts of problems with radio receivers as well. ... The bigger problem comes from a powered heterodyne radio receiver. [nice intermodulation discussion snipped]
Heterodyne receivers aren't the only problem. The current-generation of power transistors are rather wideband and can up/down-convert signals. These transistors are found in DC-DC converters, notebook backlight power supplies, hard disk motor drivers, and so forth. Most gadgets larger than a Palm have some sort of switched power circuit in them. The transistors aren't as wideband as those in radio receivers, but they can still cause problems.
This isn't theoretical either. A while back, we had to diagnose an odd problem with a pager system. There were actually two paging transmitters, and two sets of pagers, on different frequencies about 60 kHz apart. Occasionally, one set of pagers would receive something that had been broadcast on *the other frequency*. It turned out to be a computer monitor: the RF from one transmitter was getting into the monitor, being mixed with the ~60 kHz horizontal frequency, and reradiated 60 kHz up and down from the carrier. You could tune the effect by going into the Windows settings and changing the refresh rate. We engineers all thought it was pretty funny. The users, of course, were less amused.
-- ;-)
Kuro5hin.org: where the good times never end.
Mobile phones, laptops, personal organisers, radios, CD players.....
Does nobody read books any more ?
Cell phones put out about 1 W of radio power. In typical circuits, that means about 5 volts of signal. That's more than enough to upset many circuits.
So why not just shield everything? Because shielding is expensive and unreliable. The New Scientist article referred to "Faraday cages", but that's *grossly* inaccurate, since a Faraday cage only provides electrostatic shielding (by surrounding the circuit with metal). Real shielding involves seamless metal enclosures. The important thing is *seamless*. Suppose you have a perfect seamless metal box. It's a perfect Faraday cage and a good radio shield -- cell phones will not interfere with anything inside it. If you cut a narrow 0.1mmX15cm slot in it, it will still be a very good Faraday cage, but it will be a *terrible* shield. Radio waves will "shine" right through, despite the narrowness of the slot.
And in the real world, seams and slots are hard to avoid. If a panel isn't properly screwed down or has the wrong type of gasket, radio waves will go right through. If someone yanks on a shielded cable, the shield can invisibly separate within the connector, and actually end up worse than no shield at all. So you just test the shielding, right?. Wrong! Shielding is almost impossible to test. Short of *laboriously* testing every single box and cable with a signal strength meter, you can't test shielding. I would guess that testing all the shielding in an airplane would take a few hundred hours of a radio engineer's time. Nobody could afford to do that on every plane every few years. Since shielding is *never* perfect after a few years of service, and you can't really test it, it's prudent to ban powerful transmitters in the plane.
Absolutely correct. The metal structures of the plane will guide the radio energy to surprising and unpredictable locations. The upshot is that a cell phone in the front of the passenger cabin might send much of its power to an electronics unit at the back of the plane. With radio waves, power doesn't necessarily drop off much with distance, especially in a reflective environment. If you allow a 1 watt transmitter anywhere in the plane, you have to design the plane to withstand 1 watt delievered anywhere.
-- ;-)
Kuro5hin.org: where the good times never end.
the airlines could make money on those expensive phones in the plane.
Aide: Grant drinks too much to command an army. Lincoln: Find out what he drinks and give it to my other generals!
A Faraday Cage around the plane would only shield it plane from EM radiation coming from outside the plane itself: it would be of no help in preventing interference from sources inside the plane.
A Faraday Cage around all EM sensitive instrumentation would be unpractical and possibily unfeasible (since it would also shield radiation meant to be picked up - at least in part).
fB
Egads. Didn't know that..I thought it was only for takeoffs and landings that such rules applied. So much for scanning for the transponder on my return flight.
Bowie J. Poag
Bowie J. Poag
Currently you are allowed to use your cellphone while the plane is at the gate and the boarding door is open. It used to be that you could not use it at all, but within the last few years the restrictions have been relaxed a little.
There is a well-known problem with the King KX-155 (a common navigation/communication radio used a lot in general aviation) when tuned to certain NAV frequencies causes GPS receivers to lose satellites. The KX-165 seems to not have this problem. In the airplanes I fly no electronic devices have caused any nav/comm interference but I absolutely won't allow anyone to use them if we're IMC! [in the clouds]
Unlimited growth == Cancer.
Give me a break. My HT doesn't even radiate enough at LO or either IF freq to break squelch on a radio right next to it, and I've scanned it very thoroughly. As long as I don't hit the PTT, there's no way I'm interfering with the avionics
73 de N5VB (ex-KD5BIV) AR SK
Well, in my dictionary (Collins), it says "Aeroplanes" ;)
Rich
...richie - It is a good day to code.
Okay, my only question is - who's so damn important that he/she/it has to be in constant communication during an airplane flight? Criminey - can't people just relax and have a $10 cocktail and enjoy an in-flight movie? Or (gasp) read a book? Who needs to be connected ALL the time? Probably the same self important twits who try and conduct business while whizzing down the freeway at 87 miles an hour.
- "That's a big no can do" - B. Banzai
In any case, if airplane safety is threatened by radio transmissions in the milliwatt (PDAs) and hundreds of milliwatt (cell phone) range, there is clearly something wrong with the design of those airplanes and navigational systems. Those planes need to get grounded and upgraded. That's both because passengers won't stick to the regulations, and since an adversary can trivially build tiny devices that emit lots of power and disrupt a large part of the spectrum.
Ah, but I still have yet to see an aircrew member restricting use of 'airfone's (or whatever those damn things are called) while the plane is in flight. It's a cellular phone setup with the antenna bolted to the underside of the hull.
Steve's Computer Service, Hobbs, NM
To expand your horizons a bit... there are COUNTRIES that have made it illegal to drive while talking on a cell phone (without hands-free equipment for your phone)
(Norwegian text only, sorry)
http://www.dep.no/sd/publ/forskrift er/veil.html
This may be true in relatively simple areas, geographically speaking, but I'll present 3 examples here that show it isn't that simple:
1. San Diego, California. The place is full of mesas, valleys, and canyons. Line of Sight is often not very far because you're either on the side of a hill, or at the bottom of a hill where LOS isn't very far in most directions. If you're at the top of a hill, LOS isn't usually very far either because the land rolls so much.
2. San Francisco, California. Similar problems.
3. Seattle, Washington. Similar problems.
-ted
You're right - real risk analyses have to be broadly based. I was just trying to illustrate some of the statistical issues involved to those who felt that just because their plane didn't crash when the RF regs were broken, the regs must be bogus.
"Just once, I'd like to meet an alien menace that wasn't immune to bullets." -- The Brigadier, Dr. Who
I had that dream again, where I'm rolling a jelly donut, and a snake, wearing a vest... Nono, not *that* kind of dream!
-o Disclaimer: My employer doesn't even agree with me about C indentation style. o-
I think that illegalizing cell phones does not solve the problem, because with so many cell phones you'll always have someone who really forgets to switch the phone off.
This in my opinion gives a high credibility to the argument that the air carriers are only illegalizing cell phones in order to maximize profits from airplane phone systems.
No argument there, the original poster stated that 2-3 towers are the norm, and I was trying to demonstrate that this isn't the case. There is a lot of variability, sometimes you can only see two towers due to geography, and other time you'll be able to see more than that, especially if you're in a high usage area, with lots of microcells etc.
That should be "the study is clearly NOT a double blind study by disinterested parties"...
1. I work for the US Air Force, maintaining the navigation systems you talk about on AWACS. Of course, I don't speak for my employer, either. 2. Normally, my job is performed on the ground, but I fly on the aircraft I maintain when I go TDY to Saudi, Turkey, Las Vegas, etc. 3. The ILS system you speak of stands for "Instrument Landing System". "Glideslope" is the up/down portion of it. It does not use an "interference pattern" to determine the plane's position in relation to the runway. Instead, there are 2 different RF frequencies aimed above and below the desired landing angle. The signals overlap somewhat, and that's the place you want to be. If one signal is stronger than the other, you know you're either too far up or down. 4. These signals are nowhere near as susceptable to interference as you imply. There have been times I've done extensive testing on this system while toying with a laptop, or talking on a cell phone. In fact, the antenna for glideslope is located in the nose of the plane, right next to our Weather RADAR system, which is used up to the moment the gear hit the runway. It is my opinion that the FAA goes way overboard with their regulations for using electronic devices on aircraft. After all, if there's a possibility that my laptop could interfere with a critical navigation system, they shouldn't let me use it at all. And if they're worried about it interfering specifically with ILS, they should only require us to turn them off during IFR (bad weather) approaches and take-offs. Just my $.02, Randy
Something doesn't make sense here. Airports often have their own cell towers (to support in terminal demand). They also have a wide array of long range radio antennas. It's easy to see their effects as well, driving within 100 yards of the ones at the local airport turns all FM stations into static.
If the low emissions of a cell phone, or the even lower emissions of these receive only retransmissions are a factor, how can these high powered sources right out side the plane not be a huge problem? Even worse, they are right by the runway, affecting the most critical moments of takeoff and landing.
If an aircraft can be brought down by a cell phone we have huge problems. Terrorists need not bring bombs anymore, just carry on a cell phone, or worse a small high powered transmitter that would be trivial to build at your local radio shack. If this is a problem it is an aircraft problem, not a consumer electronics problem.
3waygeek is right - I must have been flying upside down!
Alright people. Everything causes interference. Everything has an infinite field, whose strength is dictated by 1/r^2. There's more invisible frequencies out there than most people can imagine. The point is that most electronics really are not that sensitive to noise.
For example, has anyone ever considered why laptops are not allowed during liftoff on an aircraft? People here are saying interference this, interference that. Ever consider that it is just for the safety of the person, so that heavy objects aren't flying all over the inside of the plane during a shaky takeoff?
This brings up another important point. Planes do fly over cell phone towers. There are several posts saying that the towers are not directional, and yes, they do have an up to 35km radius on them. And yes, they do put out massive RF traffic in all directions. However, what people don't seem to see is that the towers do not put out much RF traffic in a specific direction unless they are transmitting to that location. Therefore, no cell conversations on planes, minimal radiation. At least, that's how I think it works!
My phone is seeing quite clearly three tower where I am right now, and I'm in a small town. In high density urban areas, you quite often have more than that.
Just immagine the cell tower selection algorithim with an input size of 4000 possible towers.
You are correct that using a cellular phone in a plane causes all kinds of trouble, but this isn't the reason. Remember that cellular systems rely on channel reuse to achieve high capacity. In other words, if channel x is used on tower A, it can't be used on any of the neighboring towers, but it can be used on towers that are further away. The assumption is that with the right power tuning etc, the two towers won't interfere with each other since they are not next to each other (of course sometimes if the network is too dense there are trouble spots where this isn't the case, hence crosstalk). This assumption is based on the fact that users are close to the ground. As you said, when you are in an airplane your cellular phone can see many towers, some of them using the same channels. I'm not sure how a network would respond if one of its channels was used from a phone in a plane, but I imagine that after all the users of the channel suffered from crosstalk for a while, they would either lose their calls or handed off to another channel, rendering one channel useless in a large area. Just a few people using their phones in a plane would have a devastating effect on the capacity of the system underneath, especially if flying over a large city. Not to mention that if your provider has any fraud detection system in place you would probably trigger an alarm by appearing to be in more than one place at the same time.
He's talking about the same studies you were.
Ask any experimental scientist or statician about the difference between establishing a correlation and establishing causation. please.
Critical thinking 101, people.
DNA just wants to be free...
probably because it's not particularly effective i suppose... just because there is an interfearence with some navigation systems would more likely to cause a "scare" and maybe the plane landing badly.. or hell even over-shooting the runway!!! but it doesn't really ensure that the plane with be blown out of the sky and people sitting up and taking notice (which seems to be the an important reason for terrorists) planes can land with engines burning - so although there is a risk of a failure and we shouldn't tempt fate, terrorists aren't really gonna think this idea is any good
The public land mobile network (PLMN) was developed for LAND use, and a few assumptions were made in the process. Making the system available for a few (airborne) customers would simply make it less efficient for the rest. As with all engineering, the designs involve several trade-offs. The entire system was designed around keeping the mobile terminals cheap and mass-producable, so everyone can buy a cheap phone and use it 99% of the time. We do not have unlimited hardware budgets, and we are not trying to make the phones universally usable (under water, tunnels, on planes, at sea, etc).
The GSM standard assumes that the mobile station is moving at less than about 300 miles per hour. At higher speeds, the doppler shift becomes very significant. You do the math. This becomes a very hard (expensive) spatial geometry problem to solve for a simple 8-bit processor in a phone (that is already loaded down with a lot of protocol tasks).
The standards also assume that you're near the ground level. Sure, when you transmit, you'll light up several cells from a plane (typical PCS-band cell radius on the order of a mile or two, with a maximum radius of 22 miles). Likewise, you're hearing several base stations at once. Again, a hard problem to solve.
For more info on how it all works, see "The Mobile Telephony Primer" at http://alanporter.com. If you still have questions, send me an email.
// Alan Porter
There is an issue with the cellphone itself, apparently - they get upset when they find they are in range of too many base stations at once, since it upsets the cell to cell handoff algorithm. That's not the aircraft's problem, though :-)
Bomb detectors look for signs of unstable (read explosive) chemicals. The detector turns then a different color on the part of the object that is the unstable compound... (at least this was tested and shown to work by some research companies a bunch of years ago... I'm only assuming the airports were smart enough to use this stuff) It doesn't work by actual inspection. SO they don't have to know the difference just watch for the color change or anything that is obviosly a bomb/prohibited
"... That probably would have sounded more commanding if I wasn't wearing my yummy sushi pajamas..."
-Buffy Summers
Goodbye Iowa
Yeah, I knew that. I also know that the skin of the planes are designed to direct & disperse the energy from lightning strikes to element which are supposed to be able to handle the charge.
But I'm also thinking that the plane isn't a perfect Faraday cage (otherwise you wouldn't be able to hear radio signals from a walkman in the plane) and that the energy of the broadband EM radiation from a lightning strike is going to far exceed the puny 2 watt output of a typical cell phone.
Even if every single passenger on the plane was talking on their cell phones all at once, would it even come close to the electrical disturbance caused by a lightning strike?
While I dont paticulary understand the EE behind these problems, this has shed some light on it, and Im quite prepared to beleive it..
There are lots of weird things that can cause aircraft to crash, and being from Nova Scotia, Ive proably heard a little more about SwisAir (#whatever).. While the final report hasent been released, it looks like the major cause of the crash was bad wire insulation. There have shown (US) military tests on simmilar wire done in the early 80s, which cause them to rewire all of there planes.
The moral of the story is while it may seem like a fucked up regulation, theres proably a good reason, somewhere.
FAR Part 91 (general aviation) says PIC determines what electronics may be used.
FAR Part 121 (scheduled air carriers) restricts electronic devices. (121.305) The operator is the one who makes the determination, not the PIC - and the operator is the airline. These restrictions are usually in the airline's Ops. Specs., the operating manual; for a Part 121 airline, the ops specs have the full weight of FAR's. (Of course the PIC may forbid something not explicitly forbidden by the FAR's or the ops specs.)
The FCC regulation covers the AMPS cellular service; it does not cover - for instance - CDMA PCS.
Unlimited growth == Cancer.
You forgot one other important possiblity: 7. People with lifestyles that involve staying on the phone more than 2 hours a day may also be doing things that put you and higher risk to brain cancer. People who own surfboards probably have a somewhat higher skin cancer rate than the background, however it's not that the surfboards are beaming out cancer rays, it's that they're out in the sun a lot.
This Sig Intentionally left blank
One airline stewardess made me shut my TI-85 off and stick it under the seat during takeoff.
I've always assumed there was some kind of a reason. After all, people in positions of authority rarely act arbitrarily.
"Beware he who would deny you access to information, for in his heart he deems himself your master."
Moreover, the DAC (digital-to-analogue converter)in a CD player makes a ton of 'hash'; digital noise that can be heard in the RF band (and upper audio too). Its partly why CD sound is so bright and 'dirty' sounding. It also means CD players aren't good in airplanes.
-- Experience is a wonderful thing. It enables you to recognize a mistake when you make it again.
Brain cancer causes excessive cell phone use.
Joe Ganley
Actually, I read something about cell phones being banned in hospitals. It was a while ago.. I can't remeber the source. Regardless, the reasoning behind this is because some patients have wireless transmitters which send their vital signals, and it's feared that cell phones can possibly interfere with these.
When your in situations such as in hospitals or airplanes, where minor problems can mean the difference between life and death... it's better to be safe than sorry.
No, it's Performance Art Hacking. You take your life in your own hands when you do this ...
A hack is a hack. Whether it's by using a PC or electronic devices to control a plane, you're testing the limits of the system.
So hacking a plane via electronic devices of people flying it is the Ultimate Hack. You try, you die. Or you fly.
Best bet - do it over Nevada during Burning Man www.burningman.com so we can see the crash!
Will in Seattle
--
$x='S24;r)>63/* h@<5+oZ)32"5cz';$me='phroggy'x$];
$x=~y+ -xz+\0-Tx+;print$_^chop$me for split'',$x;
What might prevent this from happening is that before any cargo (and correct me if I'm wrong) gets onto an airplane, it's screened. I presume it's checked for bomb signatures (otherwise what's the point of having personel go through metal detectors and stuff). Why don't they check for whether or not a package is giving off RF frequencies? Just tossing a thought out there.
While I recommend it to everyone who uses computers for anything of any significant importance, it is especially important to those who:
- Design computer systems, such as software and hardware engineers, and
- Make policy decisions involving computers, such as managers and government officials
This post to comp.risks ought to put the fear of God into most computer users and suggest that us programmers need to work hard to take responsibility for our work: I bring it up in this discussion of cell phones and aircraft because electromagnetic interference in safety-critical systems is a frequent topic on Risks. For example, If you're upset about the sorry state of software these days, there is in fact a lot that can be done about it. Get started by reading Risks.Mike
-- Could you use my software consulting serv
Almost infallably people who are talking on cell phones are swerving all over the roads. I don't know WHY that is, but it is.
-- Dr. Eldarion --
Excellent, someone got it right! I worked in the Engine Controls software section of a major Aerospace company (nameless of course). The amount of time to EMI Lab test an engine control alone is in the multiples of HUNDREDS of hours. To think of testing an entire plane would be outrageous! The designs on the system 'boxes' are a specific art. They take into account all the inputs of the entire plane, when designed. (That's called static folks). Now take a yapping fool on a small electronic (large electronically) toy on that plane ANYWHERE inside. That's called dynamic people...it about equates to a non-deterministic real time system...ie => kiss your plans buh-bye! Just my two cents...
Well i have my little ibook, and I was wondering if i set up a point to point network on the plane would it have the same effect as a cell phone... Is the 802.11 going to have the same effect, what about blue tooth, even though it is limited range? Then what about the Irridum phones? Im sure some one can think of half a dozen other things that generate signals...
Yeah, this is one of those things that I wouldn't put too much stock in, that cell phones cause brain cancer.
It seems it's one of those things where people are trying to find something to blame.... and they'd do anything to believe in it. It's just like when people say that "living close to power lines" give you cancer.
I mean, think how many people have cell phones, almost everyone. Now, those people who have brain cancer, and use a cell phone, would like to blame the cell phone.
Hey, lets go..
SUE MOTOROLA...
There are a number of problems with this allocation of blame, but the fundamental one is this: Air traffic controllers and pilots are highly trained and highly paid to ensure air safety. Baggage handlers are not. If a baggage handler can make an error that kills 350 people, it is the fault of the system for allowing this, not the baggage handler. (McDonnell Douglas were correctly held to be responsible for the Paris crash.)
Similarly, passengers are not trained or paid to be aviation safety experts. If an untrained passenger using a cell phone at the wrong time causes the plane to crash, it is primarily the fault of the plane, not the passenger.
(Having said this, the bans will have to remain in place until the old planes are retired.)
Quattuor res in hoc mundo sanctae sunt: libri, liberi, libertas et liberalitas.
Numbers added: Which does not differentiate between 1. A causing B, 2. B causing A, 3. A and B both being caused by C, 4. A causing B indirectly through some other factor D, 5. B causing A through some other factor E, or 6. A and B occuring together more often due to chance.
Let's see...
1. Cell phones cause brain cancer.
2. Brain cancer causes people to use cell phones.
3. Solar flares cause both brain cancer and an uncontrollable desire to use a cell phone.
4. Cell phones cause brain cancer, but only because people's fingers contain trace amounts of uranium, and their fingers are too close to their brain all day.
5. Brain cancer causes cell phone use, but only because people with brain cancer need to call their doctors from unusual places at all hours of the day, so they buy cell phones.
6. It's pure coincidence that brain cancer correllates with cell phone use. On a side note, we at Brown & Williamson believe that it's pure coincidence that lung cancer correlates with cigarette smoking.
Your points on correllation and causation are technically correct. But, come on, use Occam's razor. One of these things is not like the others (hint: the others are ridiculous)
"Beware he who would deny you access to information, for in his heart he deems himself your master."
Sure it can! It depends a lot on the terrain and if you have line of sight, and when you're in the sky there's nothing between you and the tower. In flat rural areas it's not uncommon for one tower to cover (although not always very well) a much larger radius... In Australia, they had to come up with a hack that enabled them to exceed the 35km limitation of GSM (which doesn't have to do with RF propagation, but with timing. With GSM you might get a strong signal if you're 40km from the tower, but you won't be able to use the service.)
Just yesterday a hungarian plane returned to Prague shortly after takeoff and made an emergency landing after reporting a fire alarm - fortunately a false one. The media speculate about cell phone involved - we probably never find out whether this was indeed the reason.
...on an airplane. A cell phone on the ground has line of sight to maybe 2 cell towers at a time. Maybe 3 if you're downtown. From an airplane 30,000 feet up, you're phone's sphere of effect just got huge. Just immagine the cell tower selection algorithim with an input size of 4000 possible towers. Add to that the fact that you're going several hundred MPH and you'd be changing towers every couple seconds. You're looking at a distributed system nightmare. And there's FCC regulations that prohibit you from using your phone up there too.
It has ISBN 020155805X and you can purchase it online from:
- http://www.fatbrain.com
- http://www.barnesandnoble.com
- http://www.amazon.com
- http://www.chapters.ca (Canadian bookseller)
If you teach a course in programming at any school, I suggest you put this on your "recommended reading" list, and if you teach a course in embedded or fault-tolerant computing, I suggest you include it in the required reading.Mike
-- Could you use my software consulting serv
Kind of makes you wonder what could be done with a much more powerful transmitter easily disguised as a small am/fm radio, or even a land-based directional transmitter...
-p.
Of course. They've been telling us for years not to use cell phones, fm radios, and tvs in planes. Why? Because the radio waves and emr emitted from our little devices might trigger some irreversible chain of events that will send us crashing into the icy ocean to eventually meet our deaths in the forms of choking on our own vomit because we are too weak from swimming for our gag reflexes to function correctly. Now this may be a little over traumatized but think about it. It is correct (unlike most everything else they tell us on those god forsakin instruments from hell). Even if they do have shielded wires, and cages and whatever other doo-das and doohickeys and gadgets, I am still not going to use a cell phone on a plane. Why? Because it used to cause problems. People used to get hurt when lightning struck nearby and they were talking on the phone. It Rarely ever happens anymore, but people still get off the phone during the storms, because it USED to happen. Nothing is ever (something) proof. There is still a chance. People will still probably not use cellular phones and the such on airplanes because it bothers other people and if everyone had one such item, then they would all get horrendous interference. I don't think that any invention other than seats seperated by cubicles will encourage the use of items that may cause interference. Another problem I have is that since the wires in the airplane are shielded from interference, could the people please come down to my house and make it so I don't have to listen to pilots speaking to one another 100+ times a day when I am listening to the radio. Maybe it's my radio. Maybe My location. Maybe my antenna. Maybe the planes that fly above my house are special. Maybe I am special and only I hear them. But I doubt it. About 20 and one time about 100 times a day I hear, only when Listening to my favorite radio station, airline pilots calling towers. Now I don't know what you guys know about radios, but It doesn't really matter what frequency something is on as long as it is powerful enough and close enough and the conditions are clear. I wish the airlines could use some sort of directional or vectorable antenna to transfer signals to each other and the tower. Maybe even Microwave signals??? Does anybody els have this problem? I'm not one to gripe the entire spiel I am giving so here is my good thing to say: I think that airlines are doing a decent job in keeping up their security, safety, and other aspects, and this entire comment is just my personal opinion and observations. As I said earlier, It might just be me that experiances these things, but As I also said: I doubt it.
A persons true power is a combination of mind and body. To reach full potental you must get both to work as a si
Assuming that there is no safety issue with using cell phones on airplanes, and forgetting for the moment the legal issues, what about the technical issues?
Sure, lots of people would love to use cell phones when the plane is on the ground waiting to take off or heading to the terminal, and that should work fine, but what about at 30+ thousand feet at 600mph? You would be changing cells every minute or two. I doubt coverage is adequate, even if there's no problem with the range.
Why has nobody run such a test until now?
my exposure to aeronautics is (obviously) rusty - although I recall vividly the technique of cross-checking each instrument indication against the others in order to detect a contradiction.
I would hope that flight computers do this now, fusing all known data sources and calling for a missed approach if an anomaly is seen.
While I would not expect mention of anti-terrorism techniques in open sources - I doubt anyone can do what they did in the "Die Hard" sequel - hack an ILS to crash airliners.
If they're taking that stance on things, they might
as well go ahead and commit themselves to a hospital for all the other diseases they know they're going to get.
;-)
Insert mind here.
The regulation was originally put into place because of the strain that airborne cell phones put on the cell phone infrastructure.
:)
When you're on the ground, your cell phone transmissions are being received most likely by anywhere from 1 to 6 cells or so. When you're airborne, that number jumps dramatically...into the thousands maybe?
The original regulation was put into place because, at least at the time, it was quite a strain on the cell phone infrastructure to sort out which cell would handle that call. Arbitrating this access between 5 or 6 cells isn't too terribly difficult...arbitrating it between thousands, well, that gets computationally expensive.
I don't know what the current state of cell infrastructure is, perhaps the systems could more easily sort this out now, I'm not savvy in that area, but anyway, that's the original idea.
Jeff
You aren't allowed to use cellphones in hospitals for similar reasons.
Recently, I've noticed it's even forbidden to use a Walkman on an airplane during takeoff and landing... apparently because some people keep them so loud they couldn't hear any emergency announcements. I thought that was a bit silly. it's not like you wouldn't notice an emergency and turn the damn thing off!
"Sorry, this building's over thirty years old and can't handle the transmissions or it'll collapse. You'll have to put your phone away or be sent to the principal's office."
Ever get the impression that your life would make a good sitcom?
Ever follow this to its logical conclusion: that your life is a sitcom?
"I don't care about the Constitution!" --Bill O'Reilly, November 17, 2009
If you MUST make a call, there are phones you can use on the backs of the seats. So they cost a little more. boo hoo.
--
grappler
Vidi, Vici, Veni
but I find it hard to believe that personal electronics actually have an effect on jets (mainly because I've been on plenty of flights surrounded by people ignoring those rules -- and I've yet to be involved in a crash).
That's like saying "well, because I've drunk and driven before, and I've been on the road with people who are been drinking and driving, and I haven't crashed yet, I should keep drinking and driving, because it is therefore not possible that I will crash."
One Microsoft Way
My plan is to pimp before they realize I'm a jackass. Hit 'em hard and fast.
Here is the official FAA regulation on electronic devices in flight.
"This message is composed of 100% recycled electrons."
I think the airlines are using the cover story of "cell phones might make us crash" to get compliance from the sheeple in the cabin. If I'm a nervous passenger and the guy next to me is using his laptop, there's a greater chance I'll turn him in if I'm afraid he'll make the plane crash. Personally, I find the "navigational interference" story rather frightening: if a Gameboy with two AAA batteries can emit enough RF to bring down a 747, what other poor design decisions did the engineers make!?! I'd rather have them tell us the truth about the restrictions so we wouldn't need to keep having this argument.
Anyway, the whole point of cell phones or not is rather moot. If the captain of the ship says "No cell phones", then it's no cell phones regardless of WHY the captain says it. It's the captain's ship, and the captain's rules are Federal law. You can argue about all the technological reasons why they should (or should not) be allowed, but the decision does rest in the captain's hands, not yours.
John
John
Hold up a cell phone near the cord leading to the handset of a landline phone you're using to call it. Then come by and tell me the interference is nothing to worry about.
Need a Python, C++, Unix, Linux develop
A standard, Mode C Transponder has a recieve/interrogate, frequency and an output frequency. The tower interrogates the transponder on 1030 Mhz. The aircraft responds with a series of pulses on 1090 Mhz, transmitting its squawk mode and altitude.
The squawk mode is a kind of identifier for the aircraft. Standard, fair weather flights will squawk 1200. For a general emergency, you squawk 7700. For loss of your vocal communications radio, you squawk 7600. If you have been hijaked, you squawk 7500.
Most voice transmissions in aircraft are done in the range from 110 Mhz to 130 Mhz or so.
And yes, squawk is a technical term, they even use it in the regs
What do I do, when it seems I relate to Judas more than You?
Still not dead.
simply because there aint much use of it, w/o the plug.
yeah, don't forget the plug.
otherwise, where is going to be the "whole staying connected" business, when you just cant stop bullying around with a gadget, no more than a radio on such crouded wave-space-hogs like the big internationals?
Now, Make Your WISE Move...
Now, Make Your WISE Move...
I believe that what you're referring to there applies only to stuff like garage door openers and radio control cars, i.e. stuff that doesn't require a license to operate. I think they call that the "no interference/no protection" policy. Basically if the FCC finds it's interfering with some other licensed radio service they can make you stop using it. I doubt that aircraft radio equipment falls into this category.
I was an intern at Pratt & Whitney a few years back (they make jet engines, competing with the likes of G.E.). During my 6 months there, I got to see all kinds of talks and film clips about the industry.
I recall seeing a really cool video on lightning strikes, and how planes are designed to handle them. It always struck me as odd to hear the in-flight warnings about handheld devices, knowing that the plane was built to withstand a direct lightning hit.
Sure... some yahoo will probably make a point about how the two are totally differemt. But still, to a layman like myself, I have a tough time reconciling the two scenarios.
Well, in 1989 (equipment built before then has the problems, according to the article), a 'mobile' was about the size of a housebrick, was incredibly expensive to operate and didn't roam awfully well - so taking it abroad, or operating it on a plane, was something that was never envisaged.
It's easy to ask such questions with hindsight, but what would you have said in the mid-80s if someone had told you that mobiles in 2000 would be smaller than a cigarette packet, and would work practically anywhere in the world?
It's a violation of FCC -- not FAA -- regulations to use cell phones aboard aircraft because of the transmitting range at altitude. Your signal covers more ground, giving greater potential for interference and confusing the multiple cells you're overlapping. FCC couldn't give a rats behind if it happens to screw up navigation equipment too. (Well, except where that nav equipment is also based on radio signals.)
Now, the FAA and airlines may also have a legitimate beef, and maybe even some regulations, but it's the FCC who will slap you with a heavy fine if they catch you doing it.
-- Alastair
I couldn't agree more. Here, in Switzerland, most trains have "quiet" carriages in which you're not even supposed to talk *at all*. Of course, mobile phones are banned. At first, when they introduced this regulation, I thought it was a bit too much. But with the explosion of the number of cell phones in Europe, I now find it a great relief.
:)
Last week, I was in in for a 4.5 hrs train trip, and some mobile-addicted moron had the great idea to sit in the quiet area to call half the galaxy "because there was too much noise in the other carriages". Bah, after a while he was granted a $30 fine and had to go back to the noisy section... So I could finally sleep
I think it's just fair to be able *not* to hear the constant hummering of technology. And if security is at stake, there's no choice to be made even if the chances of electronics disruption are paper thin.
I promise to kill the first guy who makes my plane crash because he had to call his gf.
-- It's always darker before it goes pitch black.
This is purely an issue with the FCC and the choices/rules of individual airlines. There is NOTHING in the FARs (Federal Aviation Regulations) that restricts the use of any electronics while in flight. The only restriction is what the PIC (Pilot in Command) deems will not interfere with the safe operation of the aircraft.
There is however a FCC regulation that calls for a up to a $10,000 fine for use of a cell phones in the air due to the multiple-tower problem. It's FCC Regulation 22.925.
-- Nathan (PPSEL)
Not really. There are tens of millions of wireless subscubers in America, how many are going to be in the air 'sucking up bandwidth'?
Cell phones only tune to one control channel at a time. When you are leaving the coverage of one cell, the network tells your phone which channel to switch to to get the next radio.
Don't think it would cause the collapse of the cell phone network, mmm k?
There is much cruelty in the universe, John.
Yeah, we seem to have the tour map.
Most analog cell phone transmissions occur between 800 and 950 MHz. Youre going to have a hard time finding a scanner than will allow you to listen to that range. If I remember correctly, there was a law passed in '93 or so which made it illegal to sell scanners with capability in that range, in order to protect the privacy of analog cell phone users.
;-)
The next time you are in Europe, stop by a local ham radio shop. Most European countries do not block the 900MHz band for general purpose recievers. That's where I bought mine! It even has the FCC ID, even though it is not supposed to because it is not to be sold in the States. I guess the company did not want to deal with the hassle of domestic and international labels. The one label has all of the testing marks ( FCC, CE, etc ). The FCC id makes it a hell of a lot easier to get through customs.
Yes, I have heard some very interesting phone conversations on that thing. Also, don't be chattering away too freely on your digital phone either. I know a guy who was a tech at the local wireless utility, and he had access to a nice little device which he could use to track CDMA calls. I am very careful about what I say on ANY phone network after that. It's too damn spookey listening to people converse like nobody is around. I feel like a ghost! BOO!
Remember, You are unique...just like everyone else.
I remember reading about this, back when I was into the radar-detector thing, , , there wasn't one on the market yet that had something like Ka and X bands, it was either-or (1989,90?). I tried a buddie's detector with mine, and we couldn't get these two things within 6 feet of eachother without them setting eachother off. I then read up on the subject in Popular Electronics, and found out that the radar detector actually is a transmitter as well. Along with the rumor that police in Canada (where they were illegal at the time) had a radar detector-detector.
If it ain't broke, fix it 'til it is!
These are my friends, See how they glisten. See this one shine, how he smiles in the light.
So why is it more rude for a person to talk on a cell phone in the seat behind you than it is for them to have a conversation with the person next to them? If this troubles you a lot, I might suggest an inexpensive portable music making device and some nice Brahms or Mozart.
Why yes, I AM a rocket scientist!
Why use a cell phone on an airplane? After takeoff, it isn't going to work very well anyways... Usually not at all. The radio signals sent out by the towers just aren't that strong. Heck, you can barely go through an office building using a cell phone. You CAN'T go through a tunnel. Cell phone usage on aircraft just isn't terribly practical. There are other technologies better suited to it. Of course, don't use a different technology that will cause the plane to crash ending your life.
Eh...
Can you provide a reference to your "recent studies"?
ASRS (The Aviation Safety Reporting System) is a program run by NASA for pilots and other aviation workers to, without fear of reprisal, report safety issues. They have a fine website at http://asrs.arc.nasa.gov This document is a collection of raw reports relating to electronic interference with navigational instruments. Makes an interesting read.
Because then the Airlines couldn't screw you for $10US/min to use the air-phones!
-Jasa -- Linux - The SOURCE will be with you, ALWAYS
Unless it is a super-ultra-cheap CD player, I don't think the digital noise will get into the audio. They have digital and analog filters on the output to keep it out. If they use oversampling it'll be way over the audible frequency range anyway.
However, as with any digital device, a CD player can emit radio interference - although this is somewhat restricted by FCC regulations..
Only true in deep space. The rule of thumb for RF engineering in cellular is that the signal decrease is proportional to the inverse fourth power of the distance from the transmitter. Inverse square law is a good approximation for ground to air and air to ground. It is definitely not true for base station to mobile in cellular, or in general for radio transmissions on the ground. In fact, cellular does not work if the inverse square law holds.
One has to sum the phasors of the direct wave with the reflected wave from the ground. In addition, urban environments and multipath complicate the picture exceedingly, leading to such phenomena as Rayleigh fading.
"Mit der Dummheit kaempfen Goetter selbst vergebens." - Schiller
Cell phones in the air tend to overpower on-the-ground phones.
If you're travelling at several hundred MPH, you're frequently through the cell before the phone company knows who to bill.
Old planes are built to maximze discomfort, and they are specially designed to direct all that negative karma whereever you happen to be sitting.
As a frequent flier (or is it flyer), I can attest that the specific announcement is that "the cellular phone use is permitted while the aircraft is parked at the gate with the forward boarding door open." At least that's what Delta's flight attendants' standard announcement is.
Yeah, I'm picky. So sue me.....
What about the social aspects of cell phones?
I was on a train from Boston to New York (the new Amtrak Acela service), and for half the trip, the person in the seat behind me was chatting on her cell phone. That was not fun. At least at $3/minute, most people will make the airphone calls short.
I've heard that some commuter trains now have phone-free cars. Will airplanes need separate cell phone sections? Or perhaps just a noisy section (no cell phones or babies outside that section).
Perhaps some more research should go into the recent mysterious crashes that have happened in the last few years. If a cell phone was in use and the airplane went down, there could be a bigtime link!
Mike Roberto (roberto@soul.apk.net) -GAIM: MicroBerto
Berto
is still fairly rare on domestic flights. Fact is, the general belief is that a terrorest attack on a domestic flight is unlikely, and decades of terrorist free service more or less proves that. Screening of luggage is unusual because it wasn't felt necessary and the machines which do it are costly and are needed in large numbers for big airports. The matching of luggage to a passenger is the single most effective way of making sure that bombs don't get on aircraft (of course, kamikaze terrorists I guess are possible.) Everything else from checking ID card's at checking, to metal detectors is pretty much worthless and is simply a ruse to alleviate the concerns of the travelling public.
Large international airports, like London Heathrow have the machines to do screening, and I believe that more often than not, if you are on an international flight from a big airport it is likely that your bags will be screened.
There are recorded incidents of cell phones setting off smoke detectors in airplanes. While I can't cite the date (early 1990s as I recall), a person had a cell phone turned on in their luggage. When they were near their destination, someone called the cell phone. When it transmitted it's acknowledgement that it had received the page (e.g. yes, i'm here and ringing) that emission set off the smoke detector in the cargo hold.
--
$x='S24;r)>63/* h@<5+oZ)32"5cz';$me='phroggy'x$];
$x=~y+ -xz+\0-Tx+;print$_^chop$me for split'',$x;
Needless to say that the insurance company wasn't thrilled when they found out.
---
Hey, what they're really afraid of is that a cell phone at 5 miles in the atmosphere has a footprint to *hundreds* of cells - a single transmission sucks up *tons* of bandwidth.. if your plane can't handle 5 freaking watts of output, it deserves to take a dirt nap (just let me know before I board so I can find another ticket, k?). No, the real reason is that the cell phone network would collapse if people used their phones while in the air. Of course, the airlines have no problem selling you their on-board cell service at fifty dollars per second... *cough* *cough* not that the conflict of interest could POSSIBLY have any influence on the outcome *cough*.. this is america afterall!
You know, I'd been using my cellphone in airplaces for quite sometime now, my provider hasn't said anything about it...and I pay them $30/mo for the service! Now I'm gonna have to find a fscking vacuum to talk in? Man, the nearest one is like 15 miles from here...but I hear it's expensive to get to, and you need a pretty important patron...but I hear the reception sucks :). Fix that headline Cmdr Taco.
So there I was. Naked. In a refrigerator. With a potroast on my knees. Smokin a cigar. That's when it got REALLY weird.
Most people I know that use cell phones do so for convenience, not to "look cool." In fact, I generally feel like an idiot when talking on my cell phone in a crowded place -- not "cool."
Most people have no idea how little electronics is used in modern
aviation. The entire ATC system isn't anything like what is being
proposed in those nice books on OOD. Autopilots are often analog
computers. Its legal to fly most small planes in lots of places in the
US with no radios at all. Basically anything involving modern aviation
is 1/2 century old.
The transponders use tube based amps. When they get a signal they respond
with the altitude and a 4 digit base 8 code. Its all very simple but old.
Very very old.
VORs are the primary means of navigation these days. Its being
phased out by inertial navigation and in a decade or four it might get
replaced with GPS. The VORs involve a rotating antenna and a fixed one.
You subtract the phase difference between the signals and you know which
radial from the transmitter your on. If the VOR receivers (there might
be as many as 4 on a modern passenger jet) get one of the two signals
slightly out of phase you end up with a plane off course. The Instr
landing system (ILS) is based on similar concepts but you don't want a
2 degree error on the ground. Cell phones can mess with VOR receivers.
I've seen it my self.
The landing markers are AM radio transmitters. There is something called
ADF which basically points a needle towards a tuned in AM radio station
or the nearest thunderstorm.
The problem with cell phones in the air is that they will pickup up
lots of cell sites is also true. Over rural Kansas at about 5000 ft, a
phone that was "fixed" could pickup something like 500 different sites.
If the phone transmitted, all of those sites would have picked up the
signal just fine.
Can you provide a reference to your "recent studies"?
Yes, I can.
-- You see, there would be these conclusions that you could jump to
Quote:
the CAA says its results show "interference levels that exceed demonstrated susceptibility levels for aircraft equipment approved against earlier standards".
End quote
So they haven't actually any evidence that mobiles cause problems, just proof that they theoretically might.
Sounds like a non-event to me.
At the link below (which goes to TELECOM Digest V19 #457) is information which directly contradicts this newer (and apparently much smaller) study.
s /archives/back.issues/1999.volume.19/V19_% 23457
I believe that the tower-switching issue is genuine, but I find it hard to believe that personal electronics actually have an effect on jets (mainly because I've been on plenty of flights surrounded by people ignoring those rules -- and I've yet to be involved in a crash).
http://hyperarchive.lcs.mit.edu/telecom-archive
And they don't want any competition.
Notice that phone in the seat back in front of you
on the 737? The one you can swipe your card through? Even if cellular phones did work on
an in-flight aircraft, they would not want you
using them.
Somebody commented that "it would be nice" if you could use your phone while waiting to take off.
I often make a call from the plane while it's still on the ground. They don't tell you to turn them off until they "secure the cabin for takeoff."
-fb Everything not expressly forbidden is now mandatory.
So they're doing something about people using cell phones in airplanes... they say it's dangerous. Well what are they going to do about people using cell phones while driving?!?!. That's sure as hell dangerous as well! I'd like to see some laws saying THAT'S illegal.
Actually there are a couple cities that HAVE made it illegal to drive while talking on a cell phone. But that's only an extremely minute fraction of the total amount of cities... they should make something like that nationwide/worldwide
-- Dr. Eldarion --
Some years ago I was involved in a project looking at this kind of set up.
The problems are huge, and EMI is actually one of the more minor problems. You mostly solve it by using fibre or good co-ax for the cable runs and faraday cages for the electronics.
The big danger is fire. Every piece of equipment has to be certified to ensure that it won't start a fire, and if one does start that the equipment won't make things worse. Cabling is the big headache here: a cable conduit full of PTFE makes a wonderful channel for fire to spread and also creates lots of poisonous smoke. Cables need to be specially rated, as do the connectors.
Then the equipment must be safe in a crash. No broken glass, even when a passenger's head hits it. It also must not be able to fly out of the seat and hit the person in front.
It has to be cooled, even though the seatback component is surrounded by a good insulator. But at the same time it has to withstand Junior pouring his orange juice over it, and curious passengers with pocket toolkits (hello, you know who you are...)
It has to withstand vibration, pressure changes and temperature extremes (aircraft may be left parked in the hot sun or freezing cold). Components are rated for this sort of thing of course, but aircraft operation tends to put you in a corner of the envelope, and failures are therefore much more likely.
Finally you are on a strict power and weight budget.
Overall, a challenging collection of issues.
Paul.
You are lost in a twisty maze of little standards, all different.
(Imagine traveling on a 12-hour plane flight with *no walkman* --- *shudder*).
Bring your old mechanical wind-up record player. No electronics, but you need an extra seat...
Well... they are totally different.
Consumer RFI is not going to throw a 747 into a spin. The danger is that it will interfere with navigation sufficiently to cause an accident. For instance, missing the runway on an ILS approach.
A lighting strike is going to produce enough RFI, and even EMP, to interfere with pretty much anything electronic unless it is very well shielded. But its over quickly. Consumer RFI can last the entire flight.
Paul.
You are lost in a twisty maze of little standards, all different.
Sir, it is my unfortunate duty to inform you that you are a baboon.
That said, I think it's time I changed my
And I thought the airlines were just making all this up so people have to pay $5/minute to use the airfone in the headrest in front of you.
Paul.
You are lost in a twisty maze of little standards, all different.
--
This seems on the face of it a reasonable suggestion. Unfortunately, its precluded by the way large aircraft are constructed. It's not like a car where the chassis and bodywork are built first and then a wiring loom is installed. It's a lot more like a nervous system - to get at some of the cabling you would need to entirely dismantle the aircraft - take off the wings, remove the fuel tanks, tear out several structural bulkheads, that sort of thing.
There's another, far more pressing, reason to do this anyway - the insulation material used in the 60's and 70's is both prone to disintegration, and prone to causing sparks once it starts to disintegrate. It's been implicated in a number of in-air fires, and desperately needs fixing but for some obscure reason (yeah) the industry seems reluctant to deal with it.
Oh, and another reason the altitude becomes a problem is that cellphones tend to up their power if they can't handshake a base station. So if you're 35 kilofeet from the nearest base station the handset will be emitting at its absolute peak in a desperate attempt to make contact.
TomV
And although you've only noticed recently that it's forbidden, it has been forbidden for years. For some reason it was forbidden before this study was done.
(Most crashes occur during takeoff and landing, so there is particular concern about malfunctions at that time. Naturally, crashing into the ground tends to happen more often when flying closer to the ground...as well as when flying slower due to limits on speed while on the ground)
I remember reading a book on cell communication where following problem with usage in airplaines has been mentioned.
When a mobile phone moves from an area served with one base station ("tower") to another, a rather complex operation of passing control is accomplished, called "handover". It may be handled OK at the speed of a car, but at 1000Mph it can screw the cell service systems up, especially older analog ones.
Is it that easy?
Funnily enough, until recently I had laughed at the idea that mobiles would cause problems. Then, one day I put my Nokia 7110 down on my desk as it wandered off to some WAP site. I put it right beside my mouse and to my suprise the pointer started wandering across the screen. I've turned off my mobile in the terminal every time since..
I fly paragliders, and in England there can be problems with using a cell phone from altitude. I don't know if this is a legal thing, or if it just applies to the old analoge phones, but using a call phone from a high altitude could, apparently, mess up the system.
Offtopic, Inflammatory, Inappropriate, Illegal, or Offensive comments might be moderated up.
Most of the original 1969 747's are still in service. No-one throws away something that costly if they can avoid it. And when i did my pilot training in the early 1980's we started out in 1947 De Havilland Chipmunks. If it's still flying, someone will still be flying it. So the rules on cellphones need to deal with anything from surviving DC3's to the most recent 'glass-cockpit, fly-by-wire' offerings from Airbus and Boeing.
Also, it's not a case of looking for proof that cellphones should be banned from aeroplanes: this is safety-critical-world, and what matters is demonstrable safety, not absence of demonstrable danger, if that makes sense.
TomV
I don't know if it's true of GSM phones, but I heard that with the old ETACS system (in the UK), if you 'moved' from one cell to another which were about 500 miles or more apart, then the network would assume that your phone was being cloned, and disable it.
Then the stewardess came around looking for someone with a radio on. I remember that they even seemed to have the location pretty much pinned. Perhaps I was close to some particularly sensitive piece of equipment (or the plane's antenna).
In any case, the rule wasn't arbitrary back then (way before cell phones).
--
Free Software: Like love, it grows best when given away.
Standard IF (for receiver/transmitters that do downconvert) is 70 MHz. If Passive re-radiation is a problem your SAW filter is out of tolerance... yes it needs to be calibrated... 10 MHz IS the standard frequency of your local oscillator (clock). Good digital RF communication requires a very accurate clock. A rubidium standard (nuclear clock) is common. Cesium Beam less common but used in higher data rate transmissions. price tag? $5-30k... now you know why it's expensive.
Opportunities for interference arises from harmonic frequencies bypassing a properly calibrated saw filter. You can't have a frequency planner on every flight and the FCC can't seem to do their jobs despite the BILLIONS they charge the telecom companies (indirectly taxing YOU). SO, no electronics while in flight...
If voting were effective, it would be illegal by now.
We live in a confusing mess of EM signals all the time nowadays, plus of course all the natural sources of EM radiation add a considerable background level. So I'm surprised that there isn't shielding on the critical circuitry in a plane already.
On the other hand, the power of EM emissions from a mobile phone are orders of magnitude greater than the background levels. I also suspect that the superstructure of the planes act to channel the signal along the length of the plane rather than merely radiating uniformly out from the plane itself. This has implications for the positioning of critical circuitry in the plane itself - having such mechanisms at resonance points within the plane is going to make shielding either cumbersome or ineffective.
But this also must have implications for the future of mobile transmissions while flying. If people wish to remain connected to the internet or phone people on the ground, it's clear that the current technology quickly runs into difficulties both in routing the wireless mobile phone packets to the mobile phone towers and in keeping a strong EM emission from interfering with systems on the plane. So will we see an internal intranet made available inside the plane with some transmission system suitable for moving data between the ground and an airliner, possibly in the middle of an ocean? I could see a system arising using satellite uplinks and maybe adding Voice-over-IP to the mix to allow incoming/outgoing calls. We're already seeing a lot of Wireless LAN technologies arriving in offices, so I wonder whether we'll see some offshoot of that technology on our flights in the next five years.
Cheers,
Toby Haynes
Anything I post is strictly my own thoughts and doesn't necessarily have anything to do with the opinions of IBM.
Well, all that is due to standard cell phone design. I'm sure an expert could rig an airborne directional system that could safely use the ground cell towers..but it's easier to just ban them all. Particularly because there are comm services for aircraft which want telephone capabilities.
When I start reading about hollywood moguls' heads exploding, then I will believe this cell phone-cancer connection. Many of them have been using cell phones rabidly for 20 years now. But if they don't start dying soon, i am going to get the meanest cell phone available.
But this also leads to another thought: Will people start complaining about second hand EM radiation the same way they complain about second hand smoke?
:)Fudboy
:)Fudboy
I guess I'm only a Fudboy, looking for that real Transmeta
The simplest problem, and also probably least likely to affect the plane, is passive non-linear antenna radiation. Basically, an antenna connected to a non-linear passive device can re-transmit the incoming RF at sum/difference frequencies (IM distortion anyone?). Although these re-transmissions are far below the incoming RF signal strenth (and most likely the noise floor) and not likely to interfere with the aircraft.
The bigger problem comes from a powered heterodyne radio receiver. Ie, a receiver (like a standard FM radio) that down-converts the incoming RF to an IF. The mixer on board the receiver doesn't have perfect isolation, so some of the produced IF (which is heartily amplified) will leak back through to the antenna, which can re-transmit. (FYI, a mixer multiplies the incoming RF with a synthesized LO (local oscillator) to produce output at the sum/difference of those two frequencies. Work out the trigonometry if you're bored, it's pretty cool.) Once again, the re-transmitted IF power is pretty small, but it is produced, and may interfere with the aircraft's receivers. And seeing that most IF's are in the range of 10 MHz or so, there is much opportunity for interference, almost independent of device RF frequency. This is why many radios are not allowed during flights, even if they're receive only.
That's why the aircraft-certified electronics are so expensive. (example - compare prices of a marine GPS unit versus an aircraft GPS unit). The aircraft units have had many resources spent to properly shield them not only from incoming RF (other than the GPS signals, of course), but also for outgoing IF re-transmission.
This IF effect has it's beneficial uses, too. For instance, one of my coworkers lost his RC model airplane when some wind gusts picked up while he was flying it. One of his friends grabbed his multi-element yagi antenna, tuned his receiver (non-heterodyning) to the IF frequency, and by scanning around (and using variable attenuators) they were able to track down the plane. Even though it wasn't actively transmitting any RF signals!
make world, not war
Okay, now I'm a little concerned. Smuggling a bomb on an airplane is a very difficult thing to do. What ISN'T hard it shipping a crate of electronics equipment designed to give off a wide spectrum of high energy radio waves.
What's stopping a terrorist from cargo shipping an electronics system designed to take down one of the older planes? How would the airlines respond with a threat to turn on such a device? Would they even believe it?
I like to listen to what's going on, but most airlines ban radio scanners for the entire trip - not just take offs and landings. They also usualy ban Ham Radios, but I guess I'm ok with banning anything that is designed to transmit.
There's an old story, which might be an urban legend, that a plane carring a basketball team home ended up slightly off course. They determined it was because every player and coach had a handheld radio tuned to the same AM station, listening to another game that effected their rankings. The small amount of RF produced by each radio messed up the navigational equipment.
Radio receivers do put out a small amount of RF and I suppose in theory, a planefull of folks putting out a small amount of RF on the same frequency could cause a problem. This story is also from many years ago.
Many of the "older aircraft" have been retrofitted with newer avionics and "glass cockpits," essentially computers which ease many of the navigational and aeronotical chores pilots have to do in various phases of flight.
;-)
When the planes were originally designed, sans faraday cages and the like, they didn't need them, because the old, standard navigational equipment (VOR receivers, DME, ADF) didn't require them. For that matter, neither did the flight instrumentation: most of it was (and, in the smaller planes those of us who fly for fun use, still are) mechanical, using vacuum driven gryroscopes, static air inlets, a pitot tube to measure air movement (and thus airspeed). My standby vacuum system is electronic (as are the lights on the panel), but the primary vac system uses induction and works even with the electronics shut off. The plane flies just fine, and one can still navigate using pilotage (their naked eyeball).
The newer aircraft are designed to require the fancy electronics, but even they still have the old, familiar instruments most of you know from PC flight simulators.
There was an aircraft in Canada (I forget the model) which was landed safely after it ran out of fuel midflight and lost all flight systems, except the basic, gyroscopic instruments just about every aircraft since the 30's comes equipped with.
Loss of navigation is only a life-threatening concern in situations of low or no-visibility, such as the middle of the ocean (which way are we supposed to fly?) or in IMC (bad, foggy, rainy weather, now we can't fly the published approach, how the f*ck do we find the damn runway?). Even then, a quick call on the cell phone to the tower can probably get you the guidance you need (which is what I would do if I lost comm while in the soup, the FCC be damned).
The Future of Human Evolution: Autonomy
just grist for the conspiracy mill...
"Stop whining!" - Arnold, as Mr. Kimble
"This message is composed of 100% recycled electrons."
You need to think critically.
Here is an example, people with cell phones may be under more stress, and that can cause cancer.
Just because it CAN be done, doesn't mean it should!
... and *NOT* a legal one.
A number of people have pointed out that it's illegal to use cellphones on aircraft anyway. And then there're the similar restrictions about discmans, gameboys, laptops, etc.
"RF frequency can disrupt navigation / autoland / whatever, so let's ban electronics either completely or just during takeoff / landing." Yeah... Grrreat idea!!!
What people who say "it's illegal anyway" overlook, is the fact that there is just about always some yahoo who thinks that the rules don't apply to him.
They'll use those tiny headphones and keep the discman in their pocket. Or they'll use a headset with their cellphone (till the plane climbs out of cell tower range). Or they'll hide the game boy whenever a stewardess gets near. Or they'll say they're using a Palm III when it's really a Palm VII. Or mabye even, they don't mean to break the rules at all, but they just leave the cellphone ON during the flight (those suckers *DO* transmit even when you're not in a call, ya know).
You know it'll happen, no matter what laws or rules or regulations you impose, and whatever safety guidelines you publish, and no matter how many times you tell someone. It WILL happen.
And that's why the FAA needs to dump those "RF on an airplane" rules, and mandate a technological solution.
john
Imagine all the people...
Let's take an example. I'm not saying this is how it is, or anything like that, but it's a possibility. An example of how studies can appear to show cause even when they don't. There are certain groups of people who tend to use cellphones more than other groups. Figuring highly in the group of phone-users are business people, the ones who are always on their phone so they can keep in touch with the home office and stay informed of any changes. These people tend to lead more stressful lives than average. High stress has been shown to lead to heart trouble. It's not entirely farfetched to say that maybe high stress can cause or at least influence brain cancer as well. And there we have a situation where there is a high correlation of cell-phone use with brain cancer, and no causal effect at all. If these people stopped using their phones but otherwise continued on with their lifestyle before (assuming all I said above was true, and I claim no such thing, remember!) then they would still be at the same risk for cancer. Now, I am not saying that the causal relationship is false. However, you need to look beyond the obvious silliness of tumors causing cell-phone use before you can dismiss any causal relationship beyond the one you seek.
Mod down posts with a "Free Mac Mini/iPod" sig, they're spam!
I understand the electronic implications of a couple watts of radio energy being exerted on the wiring of these older planes.. but what about other devices?
Last time I was on a plane, the announcement was to turn off "all electronic devices," including cell phones, pagers, walkmen/CD players, laptops, etc. What is the danger of these other devices that are not radio transmitters?
Could my little HP48 possibly cause electronic interference in a plane's wiring? Seems a little excessive to me.
Then again, on a plane with hundreds of people's lives at stake, I can certainly understand erring on the side of safety!
Comments?
Using your sig line to advertise for friends is lame.
It seems to me that there's always ONE yahoo who seems to think that whatever legal, social, logistical, or other restrictions exist, they exist for absolutely everybody but them.
Let's see - everyone else with more than 11 items is in the NON express checkout. But me, being all-important, will use said checkout with my 19 items and try to pay by cheque even though it is cash only. And I'll complain and have the little peon who works there fired if he complains.
Ever wonder why traffic is always stopped when there's ONE LANE closed? Cause there are those who think that just letting the traffic carry on through is too slow for their too-important selves, so they ying down the free lane right up to the big red arrow sign, and cut in to whoever is hapless enough to be there at the time. If it's Boston, then they'll have the audacity to point and swerve in without stopping or swerving. And someone in a Suzuki Samurai or SUV will see this, decide that's a great idea, and try and cut across three lanes of stopped traffic to do the same.
Sir, you can't smoke on the airplane. Fine, I'll go into the bathroom and destroy the smoke alarm. What if we need it later? Ah, who cares. It won't be this flight, but a later one!
All the technology in the world won't change the fact that we're becoming a race of utter bastards with no respect for anyone or anything.
I think common decency should be taught, and enforced.
And we should lose the respect for those who take these little "short-cuts". Americans tend to respect those who live outside the rules without regard for the fact that anarchy makes noone truly free (cause you're too busy looking over your own shoulder! In a car, every intersection is a potential hazard! In the street, every person is a potential attacker!)
--- Jump!! Fire!! Bullet time!! - Lego version of the Matrix
30k feet is roughly 5 miles, right? My cell phone can't throw signal that far, in fact, all I have to do is be two miles or so from the nearest tower, and I drop service - much closer for the unfortunates with PCS service.
So it isn't about your "phone's sphere", but rather about the fact that your phone signal messes with sensitive, unshielded electronics of older planes.
As others have pointed out, the scary thing is that airlines are concerned that a 0.5Watt transmitter in a cell phone is enough to mess with a multi-million dollar plane carrying hundreds of people over cities filled with millions of people.
Should these things even be flying, now that we all know how 'sensitive' they are? These are pre-1990's planes, and flight-stress has been gnawing on them for a decade as it is. But, considering the money put into their development, and the fact that they fly over radio stations of all sorts, and within radio range of one another, and through lightning storms - should they not be more durable to weak radio transmissions than my car, for which the "car phone" was initially developed?
Shouldn't they all be retro-fitted with RF-tolerant wiring and equipment?
And are cell phones the cigarettes of the decade? They cause cancer, right?? What about 'second-hand radio emissions'? I'm sure some idiot who would use a hair-dryer in the shower, were it not for the warning label, will file a law suit within 5 years!
-- What you do today will cost you a day of your life.
Most studies do NOT show any causal relationships, just a statistical correlation. Which does not differentiate between A causing B, B causing A,...
As far as I can tell, brain cancers do not cause people to use cell phones for 2 hours a day. The studies you are looking at were probably funded by Nokia and Erricson. The studies I found were completely independent.
-- You see, there would be these conclusions that you could jump to
My point is that, at the time they were built, there was no idea that EMF could be a problem. I mean, even the radio navigation system we have in place today (and the reason you can't use electronic devices during takeoff and landing) wasn't conceived until long after many of these planes were built. At the time, most of your navigation would be by maps or, at most, very non-sensitive navigation devices (ADF, etc.). Instrument landing and the percise navigation devices required to work around JFK in the states, or even Person International in Toronto couldn't have been taken into consideration with the building of the plane.
Hmph... additionally, cellphones are bad for use on airplanes for another reason too. At higher altitudes, you can get direct line-of-sight contact with many towers at the same time, which messes with the system emmensly (which is why it is outlawed, afaik, by both Canadian and American (FCC) authorities.
Just my $0.02 CDN worth from experience.
-legolas
i've looked at love from both sides now. from win and lose, and still somehow...
I was never too concerned about Cell phones causing cancer until work gave me a Nextel L series phone (on of the 1st ones). When I use it, every Monitor and Audio speaker flicker and produce static within a 5 ft. radius. Call me crazy, but I'm not to thrilled that these signals disrupting my monitors are passing thourgh my head :)
Don be an idiot. Without cell phones the US would win the war on drugs.
The use of personal electronic devices on aircraft has been debated a lot in the literature. The issue is resonance. An aircraft cabin is basically a long metal tube. So if your laptop hard disk puts out the right frequency, the signal may be amplified and interfere with the electronics. One result I've seen (I think this was IEEE Spectrum) is that a laptop hard disk put out the same frequency used by navaids. There is no consensus on this, so the FAA takes a conservative stance.
As for Hemos' suggestion of Faraday cages, the issue is really cost. How much more are you willing to pay in ticket prices to haul around a cage so that a few passengers can play Doom? Also, remember that the flight instruments are housed in the same metal tube, so you'd have to put a second cage around that section of the aircraft. And I suspect it is far easier to say, "put a cage around it" than it is to actually do so. For one thing, people kind of like those pesky windows...
Weight is such a big factor that aircraft manufacturers went to Kapton wiring because the insulation weighed less. And yes, all the wiring is sheilded. But I can tell you from firsthand experience that even twisted, sheilded pairs driven by differential transceivers are affected by impressed noise.
Have you ever seen an RC plane take a 'radio hit' from some else's transmitter? Same deal with PED's; you'll never know what frequencies are being emitted, so why take chances?
I wouldn't be surprised that with studies like these only "approved" devices will be allowed on airplanes for the duration of the flight, not just take off and landing. -- Rob O'Neal
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This is a boring sig
I understand why cell phone and radio use is banned in airplanes, but why do some companies also ban portable CD players?
I was on a Lufthansa flight recently and they made me put away my player for the entire flight. Does it really cause that much interference?
if(!toilet_paper) roll.replace(new roll);
There's another reason as well - any receiver is also a transmitter. Therefore, if you use the walkman as a radio, you risk transmitting interference.
It involved a passenger listening to an FM radio while a plane was on an instrument approach in the 1950s. The local oscillator leakage caused a false indication on one of the ILS (Instrument Landing System) instruments (I think it was called the localizer). The VHF aeronatutical band is just below the commercial FM band, by the way.
Anyway, the plane crashed, the NTSB figured it out, and then made the rule about electronic devices.
Fortunately, all commercial jetliners now use inertial navigation systems, so this particular failure mode is much less likely. A terrorist would not be able to crash a plane in this way. ILS systems are still in use, however -- and nobody wants to find out about another electromagnetic compatibility problem via an accident investigation.
The aircraft units have had many resources spent to properly shield them not only from incoming RF (other than the GPS signals, of course), but also for outgoing IF re-transmission.
:)
Not only that, but fortunes have been spent on certification of such shielding, and of reliability. A technologically identical unit that has not gone through the time and money consuming process of being certified is always cheaper. It can do the same exact job just as well, but it hasn't got a piece of paper to back it up.
Sort of like a diploma, eh?
-- What you do today will cost you a day of your life.
1. The cell system was designed for slow moving ground-based users. Assumptions about signal strengths and frequency sharing were made based on that design. A fast moving high phone can disrupt service over a large area. A dozen of them can do more damage.
2. An airplane is a metal box, which means that signals do not go out very well. On analog systems, the ground and air ends of the links will be pumping out full power, which increases the problems at both ends.
3. Being a metal box, it makes a very good waveguide, especially at UHF and SHF frequencies. That means that a low level signal can be focussed where it is not wanted. That focus point will depend on where the phone is in the plane, which could be anywhere from rear overhead storage to under the front seat, or in the toilet.
4. The navigation signals are often located a hundred miles away; the cell phone is a few feet. Inverse square law applies. Three watts at ten feet is the same as three hundred watts at a hundred feet. You get the idea. A strong signal does not need to be on frequency to disrupt navigation, desensing the input stages of a receiver can prevent reception of other signals.
5. During an approach, an error of just a few hundred feet in position can be the difference between safe arrival and 11 o'clock news.
6. The frequencies used by cell systems are in a band allotted to GROUND mobile, not AIR mobile, and as such it is illegal to use a cell transmitter (i.e. a cell phone) while in the air. GE Airmobile systems are in a different band. (This is US specific.)
6 very good reasons. Can we stop hearing about "no good reason"?
a = b = c
is C's a = ( b == c ), not b=c,a=b;
Transmitters will obviously cause problems. I'm an amateur radio operator, and I've seen 2-meter (144-148Mhz) handheld transmitters (0.5-5.0 watts of power) really confuse nearby electronics. (Particularly video cameras...)
.Dave.
However, RECEIVERS can also cause problems. As I recall my theory (it's been a few years), most FM receivers use a common FM circuit that works at a particular, relatively low, frequency. The signal you want to receive (f) is then combined with a generate signal (f'), generating f+f' and f-f', filtered so you just have f-f', and then handled by the FM receiving circuit at the standard frequency.
It turns out that, for the standard commercial FM band, f' falls smack in the middle of the aircraft band.
Then you also have to consider that your generated f' signal is located a few meters away from the airplane's receivers, whereas the ground-based signals are located a few miles away. Remember how signal strength falls off with the square of the distance? Plus the aircraft band is mostly AM, so it's really susceptible to interference to begin with...
Just how important is that game of DOOM to you anyway?
The American designation is the Cessna O1. Cessna 305 is the civilian designation.
The "O" is for observation, as it was used to fly really low to the jungle (and has a huge engine, so it can climb really quick... which is why it's used to tow gliders)
-legolas
i've looked at love from both sides now. from win and lose, and still somehow...
Cell phone interference to airliners has been discussed there extensively.
For those of you who work where they're considering replacing a real OS installation with Windows NT, consider this post I contributed:
USS Yorktown dead in water after divide by zero
The Yorktown has to be towed back into port after a sailor entered "0" into a data entry field and it crashed the ship's entire NT network.
Mike
-- Could you use my software consulting serv
Let's get this straight, folks. Photons from cell phones (or power lines as well, for that matter) do not have even a fraction of the energy needed to generate free radicals such as singlet oxygen (responsible for most carcinogenic genetic damage), let alone to break peptide bonds directly. In short, cell phones are incapable of damaging DNA or creating chemicals which can damage DNA. They might cook your flesh if operating at sufficiently high power levels (which they don't), but they won't cause cancer. For that, you need ionizing radiation (UV and up...). Saying that cell phones can cause cancer is like saying that the wake from a surfboard can capsize a supertanker.
If you are really worried about cancer, stay out of the sun, watch what you eat, and don't smoke. And try not to worry about the fact that there will still be a one-in-a-bazillion chance that one of the numerous stray cosmic ray gamma photons constantly bombarding your body will happen to nail the telemerase inhibitor in one of your cells and turn it cancerous...
I want to know how the electronics on a plane can get affected by the output of a cell phone, and not get totally roasted by flying through a lightning storm!