Question:
As I listen to WLS FM, I am reminded of something I did a few years ago before I became a frequent flyer. I played the radio part of my Walkman. A stewardess came over and reminded me that it was against FAA regulations. So, I have to ask. With today’s sophisticated equipment, (like a 747-400) what can the radio portion of a walkman really do to the navigational equipment of a plane? Are there any recorded incidents of navigational equipment going haywire because of a walkman? Is the danger because a walkman has the possibility of putting out signals instead of just receiving? The talk DJ just suggested that a way terrorists could sabotague a flight would be to load a suitcase with 50 walkmans all on. He was being sarcastic, but is this something to worry about? –Ken
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>I’ve always wondered, too, why listening to a radio station could cause any >harm since it would be silly to have a plane crash or go off course just >because someone happens to be listening to a radio station.
rec.aviation covered this topic a few months back. I’ll try and get the details straight. If anyone from that discusion is here, please add what you know. The way I understand it, it is an old regulation that dates back to when the electronic equipment of the plane and the personal walkmans was not as well made as they are today. A receive only radio does transmit a fairly weak signal at the frequency it is recieving + 10. So if you were listening to 101.5FM, it would transmit on 111.5, which is right in the middle of the aircraft navigation band. With today’s hi-tech equipment, the transmit should be minimal, but there is also the fear that if someone takes an ancient walkman on a plane, the hi-tech gadgets might be overwhelmed by it. About five years ago or so, I was on a flight and hadnt heard about the regulation yet and was listening to the local FM station as we made our approach to NY. We landed safetly, but I would not do it again. I hope this sheds some light on why it is against regs to use the radio part of your walkman in flight.
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Apparently there is some somewhat reasonable reason for disallowing the use of radios on jetliners, but I don’t expect to ever see this changed since airlines make plenty of money selling those earphones so that you can listen to *their* radio. Actually, I’ve always wanted to take a Walkman on, and when the stewardess comes over to tell me to turn it off, listen to her incredulously, and then jump to my feet, saying, "OH MY GOD!!! You mean if someone uses a radio on board the plane will crash?!? Let me out of here!!!" ;-) Mike — It could be worse–you could be bicycling in Florida.
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A Walkman, or any other modern radio, doesn’t just have the possibility to transmit, it _does_ transmit. It transmits a signal which it mixes with the incoming signal to get a combined signal that it can then send to your ears. (Follow that?) The signal it transmits is quite weak, and doesn’t matter most of the time. I suppose the chances of one single walkman screwing up the navigational system are pretty remote. However, if they were allowed you probably would _not_ have just one single walkman, radio controlled toy, etc. in action at any one time. Also, how many unnecessary chances do you want to take at 35,000 feet? -Cindy Kandolf Trondheim, Norway
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>Apparently there is some somewhat reasonable reason for disallowing the use of >radios on jetliners, but I don’t expect to ever see this changed since >airlines make plenty of money selling those earphones so that you can listen >to *their* radio.
That’s not the reason, since it is only radios, not tape or CD players that are disallowed. I have traveled with both numerous times over the last 5 years, and have only been asked to turn it off during takeoff and landing in order to be able to hear any emergency instructions. Airlines that I have used them on include United, Continental, TWA, and American. Bill Hery AT&T Bell Labs 201-386-2362
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Well, it is all kinds of radios, like scanners, also. This is because they put out RF distortions, and it screws with the radios, and navigational equipment. FM radio is 88-108 MHz, and the avation voice band is at 120 MHz, so there’s not a big jump for the interference. Matt — Matthew S. Crispin I was me, IRC= Fade2Blak MetallicA ’Fade To Black’
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I would disagree with the theories that have been posted here as to how a radio actually works (having taken quite a bit of physics, I’m in a position to do this). Here is how a radio works (in a basic-ish sense): The transmitting tower on the ground adds the stuff that you want to hear to a carrier wave (101.5 FM, for example). Since it radiates outward, the original energy in the wave gets dissipated, in a manner inversely proportional to the cube of distance (its a three dimensional situation). The signal that arrives at your reciever (ie Walkman) is very weak, therefore. Now your tuner picks up this itty-bitty signal, and is able to amplify it. It accomplishes this by you varying the capicitance of the tuning circut, and therefore the resonant frequency of the circuit. What this means is that when your tuner says 101.5 FM, the circuit is resonating (and therefore ampilifying) the signal. <This is all done passively, with the Walkman doing nothing to transmit a signal directly.> Then, once the signal is ampilfied enough, it continues on to the headset, and into your earphones. However, though the Walkman does nothing directly to transmit, it does send out a signal. Why is this? Because as the circuit is resonating (to amplify the signal going to your ear), the electrons in the metal are accelerating and decelerating. This is the cause of electro-magnetic waves, and the thing that can screw up an airplane’s navigational signal. This troublesome detail is taken care of by shielding the resonating circuit with a metal box (a law by the name of Gauss’s Law is the reason for this). Basically, the metal box doesn’t allow electro-magnetic waves in or out. (The signal enters the box via an atennae, which is how the signal gets into the box to be resonated.) However, since the shielding does not cover the entire circuit (it would be impossible to do so if you were going to put an antennae into the circuit), a small portion of e-m waves do escape. How modern your Walkman is has no bearing on the situation. Actually, I’d assume that modern Walkmen omit the shielding in an effort to trim weight. I hope that this has helped you understand why it is that radios are prohibited on flights, though tape-players are. A well-shielded Walkman will emit less e-m waves than a poorly-shielded tape-player, which is kind of stupid, IMO. And I’d expect that the regulation stems from some misguided information, though I wouldn’t stand on that fact as I know little about airline communications/navigation.electronic equipment. So, to play it safe, and considering just how little time you actually spend in any one station’s range, just bring along some good tapes or CD’s to listen to if you wanted to listen to music… Phil Miesle
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Does anyone know the true regulations about electronic devices on commercial flights? What about laptops, gameboys, etc.?
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I do find the regulation little iffy as well regarding listening to Radio station on the air. Here’s the reasons: 1. Todays radio equipment are shielded to reject interference from external sources… such as transponders, 2nd radio in console, other equipment in the cockpit etc.. 2. Low freq radio waves up to microwave signals are used around airports. These are lot more powerfull than your radio listening device output so why haven’t we heard more about mishaps around airport regarding navigation/radio error? 3. Amateur Radio Operators have transmitted and received radio messages including 2 meter band (FM) on special flights. Has there been any interference noticed at that time? 4. I would think that laptops produce more interference than the AM/FM radio. 5. What about those phones used on some airplanes? Why are they not banned? Thes are some of my quarks regarding radio usage… As for myself, Listening to a radio on the air sounds like a bad time since you would need to change stations quite often as you are flying over different cities. Naoya "Nish" Nishimura
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> I would disagree with the theories that have been posted here as to how a > radio actually works (having taken quite a bit of physics, I’m in a position > to do this). Here is how a radio works (in a basic-ish sense):
… explanation deleted … I agree with what Phil has explained here, but I like Cindy Kandalf’s explanation better. :^) If this were sci.electronics, I would like Phil’s explanation instead. :^) In summary, Walkman’s have the potential to interfere with aircraft communications due to the way that intermediate frequencies are utilized within the Walkman. The difficulty is, in explaining this to a grandmother of eight or an accountant. Even Phil’s explanation as basic as it was (and he did a wonderful job of making it basic), fails to explain it in pure layperson’s language. But please, enough about Walkmans. The policy is not an airline plot and it’s not to sell more earphones (they are free when there is no movie!), it’s just to clear the airwaves. Really, I promise. By the way, did anybody ever see the movie, "The Last Flight of Noah’s Ark"? In the movie, a nun places a small portable radio close to the instrument panel. Much too late, the pilot notices the radio, removes it and shuts it off. Now they’re way off course. They have a crash landing, hence the movie’s name. Real life? Of course not. But safety first, please. — Larry Autry Silicon Graphics, St. Louis
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>Does anyone know the true regulations about electronic devices on >commercial flights? What about laptops, gameboys, etc.?
I dont have the FARs (Federal Air Regulations) handy, but for the most part it is up to the airline to determine what can and cant be used. Most laptops/gameboy-type-things are approved. The only way to be sure is to check with the airline. If you want the reference in the FAR, send me mail and I’ll find it for you. I wouldnt worry to much about it unless your laptop has a built in cellular phone… Cellular phones are a big NO NO in airplanes. This is not to be confused with the air-phones installed on some planes. John — John Clear ‘The best way to accelerate ’Hard work may not kill me, an IBM is at 9.8m/s^2′ but why take the chance.’
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Surely, all the electronics on the plane are and should be shielded from stray EM waves. So what so special about the EM waves from a walkman or whatever that they can get pass the shielding of the avionics ? — Anthony Lee (Time Lord Doctor) (These are my opinions !) SNAIL: Department Computer Science, University of Qld, St Lucia, Qld 4072, Australia
Response:
>As I listen to WLS FM, I am reminded of something I did a few years ago before >I became a frequent flyer. I played the radio part of my Walkman. A >stewardess came over and reminded me that it was against FAA regulations. >So, I have to ask. With today’s sophisticated equipment, (like a 747-400) >what can the radio portion of a walkman really do to the navigational >equipment of a plane? Are there any recorded incidents of navigational >equipment going haywire because of a walkman? Is the danger because a >walkman has the possibility of putting out signals instead of just receiving? >The talk DJ just suggested that a way terrorists could sabotague a flight >would be to load a suitcase with 50 walkmans all on. He was being sarcastic, >but is this something to worry about?
The reason is that one of the primary navigation aids, the VOR system, receives navigation information on a band just above FM. Most radio receivers use a circuitry called super-hetrodyne (sp?) which involves actually generating a very low power (plus usually a few harmonics) on the band received. Thus, it is very possible that a poorly designed FM receiver could cause a serious problem. There are other navigation systems for enroute travel on an aircraft (such as interial systems) which would not be affected, but the VOR system is used as the primary means of navigation during the approach phase (landing) of the flight. Here, it is quite possible that a poorly designed FM receiver under the right circumstances (i.e. the FM receiver tuned to the "right" station and the approach landing system tuned to the "right" station) could cause a very serious situation where the pilot would receive misleading navigation signals. — Columbus, OH …!uunet!onetouch!phil "I stayed up all night playing poker with tarot cards. I got a full house and four people died." – Steven Wright
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|> >Rather, some people listen to a walkman SO LOUD they would not hear |> >emergency evacuation announcements by the stew’s. |> > |> Sorry, to say that is incorrect, although I don’t have a reason to answer the |> original posting. In the airline magazines (placed in the pocket in front of |> you), it says that you cannot use radio equipment while a tape-playing |> machine is okay. It says, though, that you must remove headphones during |> take-off and landing (to listen to the lovely safety instructions at the |> start of the flight, etc.). I can’t believe the headphone removal policy is due to listening to flight instructions. If it is true, then they should wake up everyone who is sleeping during take-off and landing!! — Yum Ting Lui Data Services Division (513) 865-6800 X4387 …!uunet!meaddata!luiland [*1] We Put Page Numbers On The Line.
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Schmidt) writes: >Does anyone know the true regulations about electronic devices on >commercial flights? What about laptops, gameboys, etc.?
Those sort of gizmo’s are allowed but I think they are carefully checked by security, because an exploding electronic device was responsible for the Pan Am disaster. British Airports frequently ask you the question, "Are you carrying any electroncial devices?" Not because they won’t let you take them. They do that to check that they are indeed electrical devices and not explosives. BTW don’t use a laptop on the tray table. It’s really annoying for the person whose chair its on. =) Ben Dawson Trintiy College
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>Surely, all the electronics on the plane are and should be >shielded from stray EM waves.
Yes, *except* for the radio antennas which are specifically designed to pick up weak, `stray’ EM waves. An aircraft’s navigational radios receive transmissions in the 108 – 117.9 MHz band. It follows that anything in the cabin transmitting in this band may be picked up by the aircraft’s radio antennas and may cause interference with the navigational signals being transmitted by ground radio beacons. > So what so special about the EM >waves from a walkman or whatever that they can get pass the >shielding of the avionics ?
As someone has already pointed out, FM radio receivers may emit a frequency that is 10MHz above the frequency of the radio station that is being received. The FM radio band is from about 88 – 107.9MHz. Adding 10MHz gives 98 – 117.9 MHz, which overlaps with the aircraft navigational frequencies. — Nigel Gamble uunet!modcomp!nigel
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>Does anyone know the true regulations about electronic devices on >commercial flights? What about laptops, gameboys, etc.?
—– Federal Aviation Regulation 91.21 Portable electronic devices. (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 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) 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 certicate, 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. —– For a scheduled airline flight, the `operator of the aircraft’ is the airline itself (not the pilot) which will have its own rules about which devices it allows (under (b)(5)). So you just have to ask the flight attendent. — Nigel Gamble uunet!modcomp!nigel
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>Surely, all the electronics on the plane are and should be >shielded from stray EM waves. So what so special about the EM >waves from a walkman or whatever that they can get pass the >shielding of the avionics ?
Fistly the radio receivers are not shielded from radio waves (how would they receive). Now if you tak the average poorly built FM radio it radiates 10.6 Mhz above the station you are tuned to – this is bang in the middle of the frequency range used for VOR navigation. This is all rather speculative as in the vast majority of cases it’s not going to make any difference at all. However would you like to be on the 1 in <some large number> flight where the plane flies into CumuloGranite ? John (Private Pilot & Radio Ham) — John Pettitt Specialix International, London (well close anyway). Disclaimer: Me, say that ? Never, it’s a forged posting !
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- Hide quoted text — Show quoted text – >Federal Aviation Regulation 91.21 Portable electronic devices. >(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 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) 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.
Thank you Nigel for posting that info. I have no trouble with the regulation, and I have no desire to test the airplane navigation system. The problem I have is that the average leisure traveler does not know about this rule because, for some reason, the airlines dont publicize it. I know its against FAA regulations to smoke on a domestic flight. I know you’re not suppose to tamper with the smoke detector in lavatories. I know seat beats are supposed to be fasten and tray tables upright when taking off and landing. I know that you’re supposed to be in your seats until the plane has landed. But WHY, if a few walkmans are dangerous, dont they make the announcement at the beginning of the flight? Why should it be up to the flight attendant to stare at your walkman to see if the tape part is playing or the radio? Why is the text of this regulation in a font as small as the info for luggage liability? If a bunch of people with walkmans have the potential to alter the path of an aircraft, I think the airlines should mention this at the beginning of the flight. I’ll get off my soapbox now. –Ken
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> Surely, all the electronics on the plane are and should be > shielded from stray EM waves. So what so special about the EM > waves from a walkman or whatever that they can get pass the > shielding of the avionics ?
Aircraft avionics are shielded for odd sinals coming from OUTSIDE of the aircraft. –Kauto — * Mail: Kauto Huopio, Punkkerikatu 1 A 10, SF-53850 Lappeenranta,Finland *
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> A Walkman, or any other modern radio, doesn’t just have the possibility > to transmit, it _does_ transmit. It transmits a signal which it mixes > with the incoming signal to get a combined signal that it can then send > to your ears. (Follow that?) The signal it transmits is quite weak, > and doesn’t matter most of the time. I suppose the chances of one > single walkman screwing up the navigational system are pretty remote. > However, if they were allowed you probably would _not_ have just one > single walkman, radio controlled toy, etc. in action at any one time. > Also, how many unnecessary chances do you want to take at 35,000 feet?
Yep, the oscillators which create signals to mix with the incoming detected signal (in the radio Walkman) do in fact transmit a small signal…although it doesn’t really matter if you are playing one Walkman or four thousand…the signals are not additive in that way. What the problem is is that even the small signal generated may conflict with a frequency used in any of the airline’s electronics, especially if you consider harmonics. I would think that it would be near impossible to get said airliner to crash, but you could certainly get a lot of people upset, say, if all of the navigational equipment became unreliable during an inter-continental trip. | James O. Payne, Jr. | | IKEA NA Information Systems | | Plymouth Meeting, PA 19462 USA 215/834-0180 x343 | | "It’s a big country. Someone’s got to furnish it." | | (IKEA is much too busy selling furniture to pay attention to my | | drivel, let alone to be responsible for it.) |
Response:
> >As I listen to WLS FM, I am reminded of something I did a few years ago before >I became a frequent flyer. I played the radio part of my Walkman. A >stewardess came over and reminded me that it was against FAA regulations. >So, I have to ask. With today’s sophisticated equipment, (like a 747-400) >what can the radio portion of a walkman really do to the navigational >equipment of a plane? Are there any recorded incidents of navigational >equipment going haywire because of a walkman? Is the danger because a >walkman has the possibility of putting out signals instead of just receiving? [...] > The reason is that one of the primary navigation aids, the VOR system, > receives navigation information on a band just above FM. Most radio
All the talk has been about FM radio, and how the FM frequencies are close to the aircraft navigation frequencies. But what about AM (medium wave, for those outside North America)? I know it’s hard to get AM inside the big metal tube that makes up the aircraft, but assuming you can receive it, will it cause any trouble? Come to think of it, what about short-wave? –Robert Book
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Schmidt) writes: >Does anyone know the true regulations about electronic devices on >commercial flights? What about laptops, gameboys, etc.?
I don’t know about GameBoys, but I’ve been told that to use a computer mouse is against regs… seems that those nice, long cables are wunnerful broadcast antenna for signals that might interfere with flight systems… — Brian