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AM radio reception inside passenger planes?
I have no trouble receiving FM radio broadcasts on a small am/fm radio I sometimes listen to while onboard commercial jet airliners (flying at cruise altitude), but I never seem to be able to pick up AM radio stations. It's just static across the AM band. Any explanation for this? |
Any explanation for this?
FM radio generally operates at longer range than AM radio, however it's limited to line-of-sight. However, when you're 40,000 feet up you can "see" a lot of transmitters hence the FM signals. Cheers, Geoff Glave Vancouver, Canada |
In message HxHud.9448$eb3.8331@clgrps13, Geoff Glave
writes Any explanation for this? FM radio generally operates at longer range than AM radio, however it's limited to line-of-sight. However, when you're 40,000 feet up you can "see" a lot of transmitters hence the FM signals. Cheers, Geoff Glave Vancouver, Canada The window holes are much too small to let the much longer wavelengths of the 'AM' signals through. The body of the plane is a very effective screen. The 'FM' signals can squeeze in, but it helps if you have a window seat. I've also listened to SW in the middle of the Atlantic. Flying from the UK to Florida, on the other side of the Atlantic the first FM stations you hear are usually speaking French (from Quebec) It's quite alarming! Ian. -- |
"Geoff Glave" wrote in message news:HxHud.9448$eb3.8331@clgrps13... Any explanation for this? FM radio generally operates at longer range than AM radio, however it's limited to line-of-sight. However, when you're 40,000 feet up you can "see" a lot of transmitters hence the FM signals. Cheers, Geoff Glave Vancouver, Canada I reckon you just answered the wrong question !! The reason A.M. radio can not be received in a plane is that it is a Faraday cage to the (lower frequency) A.M frequencies, whereas the VHF frequencies can just about get through the windows. There may be a bit of frequency / range issue as well but top band and 80 mtrs gets across the pond so I don't think this is the issue here... Nick |
No one has mentioned that in many cases you need the pilot's permission to
operate a radio or other electronic device for that matter on a commercial airliner. That includes AM/FM radios. Radio emissions may screw up the plane's avionics. See URL: http://www.fordyce.org/scanning/scan.../scan_fly.html It sez: "The FAA does not allow inflight use of walkie-talkies, radio controlled toys, AM/FM radios, portable telephones, or portable television sets, all of which may affect aircraft radio and navigation equipment" Also cruise ships may deny use of two way (FRS) or ham radios -- always check with the communications officer. For Hams always check with the person in charge on any commercial transportation, busses, taxi's, ships planes etc. Yeah yeah I know you did it without getting permission, but read the URL as to what airlines have published. And I know from personal experience that some cruise lines do not allow FRS or ham radios transmissions. -- RF Gotta Go SomeWhere "nick smith" wrote in message ... "Geoff Glave" wrote in message news:HxHud.9448$eb3.8331@clgrps13... Any explanation for this? FM radio generally operates at longer range than AM radio, however it's limited to line-of-sight. However, when you're 40,000 feet up you can "see" a lot of transmitters hence the FM signals. Cheers, Geoff Glave Vancouver, Canada I reckon you just answered the wrong question !! The reason A.M. radio can not be received in a plane is that it is a Faraday cage to the (lower frequency) A.M frequencies, whereas the VHF frequencies can just about get through the windows. There may be a bit of frequency / range issue as well but top band and 80 mtrs gets across the pond so I don't think this is the issue here... Nick |
Some Guy wrote:
I have no trouble receiving FM radio broadcasts on a small am/fm radio I sometimes listen to while onboard commercial jet airliners (flying at cruise altitude), but I never seem to be able to pick up AM radio stations. It's just static across the AM band. Any explanation for this? Yes, there is. The AM cops have figured you out, since what you are doing is illegal on commercial airliners. The FM cops are a little slower, but they will pull the plug on you also, eventually. Seriously, though, you are inside a metal cigar tube you call an airplane, and you are being shielded by the body of the aircraft. Although windows (portholes, not Gates), and the metal itself, don't block out signals completely, you will see an effect from this (look up "Faraday Cage" on google). AM broadcast is a very long wavelength (hundreds of meters long) whereas FM broadcast is a smaller wavelength (around 3 meters). If you were trying to throw a bunch of marbles through an upstairs window, you would probably be able to do it. But if you were trying to throw a bunch of beachballs through an upstairs window, it wouldn't be as easy, right? The aperture is the important issue. Although the airplane is not a completely shielded RF-proof "screen room", it acts somewhat like one. That is why avionics antennas are on the outside of the plane, not inside. That is also why there is a teeny mesh grid in the door of your microwave oven - they have to be that small to block the microwaves. Using my example befo if you are throwing beachballs (AM broadcast), or marbles (FM broadcast) or a handful of sand (microwaves), how small would you want the window to be in order to block it? OK, getting back to my first paragraph, if you are ever on a plane with me, please let me know, so I can take the next flight. The local oscillator of FM receivers is often on the same frequency as the VOR stations that airplanes use to naviagate with, and can cause interference. There are failsafe solutions that the pilot has, to deal with loss of VOR coverage, but I don't want to depend on them because you are listening to gangster rap at 32,000 feet. Get an iPod or something. All the best, Dave |
On Sat, 11 Dec 2004 14:11:44 -0800, "Ed Price"
wrote: You are asking him to allow a potentially dangerous device to be operated just for your convenience and entertainment. Switch roles for just a minute. Hi Ed, This would make sense (to switch roles) if the administration hadn't trumped that call. Reports recently indicate that the FAA may soon allow anyone, anytime, to make cell phone calls while in flight. Anything goes for a price. The FDA has proven that it is no longer the watchdog of medicine, and the FCC is the gateway for spectrum bargains and marketplace sweeps. With these acronyms, one may well wonder what the "F" stands for. 73's Richard Clark, KB7QHC |
What a load of horse ****.
You guys are acting as if the engines and flight control surfaces of an aircraft are intimately tied to the plane's radio receiver, and the slightest odd or out-of-place signal that it receives is enough to send any plane into a tail spin. All this while the air travel industry is considering allowing passengers to use their own cell phones WHILE THE PLANES ARE IN FLIGHT by adding cell-phone relay stations to the planes and allowing any such calls to be completed via satellite. So I guess the feeble radiation by my FM radio (powered by 2 AAA batteries) is enough to cause a plane to dive into the ocean, but the guy next to me putting out 3 watts of near-microwave energy is totally safe. What about my hand-held GPS unit? Any chance me using it (during all phases of a flight, which I do routinely) will result in a one-way ticket to kingdom come? Getting back to the original question (poor to non-existant AM reception), I understand the idea of aperature and long wavelenths of AM radio and the size of airplane windows - but what about the effect of ALL the windows on a plane? Don't they create a much larger effective apperature when you consider all of them? And since the plane isin't grounded, isin't the exterior shell of a plane essentially transparent to all RF (ie it's just a re-radiator) because it's not at ground potential? |
On Sat, 11 Dec 2004 19:10:18 -0500, Some Guy wrote:
Getting back to the original question (poor to non-existant AM reception), I understand the idea of aperature and long wavelenths of AM radio and the size of airplane windows - but what about the effect of ALL the windows on a plane? Don't they create a much larger effective apperature when you consider all of them? This becomes a matter of the distance between them and the phase separation at any wavelength. What you describe is a common technique for coupling power between waveguides (in what are called directional couplers). However, this is not the same thing as accumulating and enlarging an opening because such couplers will add energy in one direction, and subtract it in the other (which makes for their directionality). And since the plane isin't grounded, isin't the exterior shell of a plane essentially transparent to all RF (ie it's just a re-radiator) because it's not at ground potential? Ground does not always mean "at one with the dirt and rocks." At one time it did, when cowboys put up talking wires, and indians pulled them down. Ground has since come to mean "common" (which when you think of it, brings us back to dirt, metaphorically). Common means that everything is at the same potential. If there is no potential difference, then there is no way to measure a voltage based signal. In other words, it's a massive short circuit, and the only way to sense a signal is to inductively couple to the short circuit current. This takes us to the second killer courtesy of physics. High frequency current travels on the surface of smallest, positive radius. AM frequency qualifies here in spades, even though it is conventionally called not HF but MF (even VLF qualifies as High Frequency in this context). The aircraft frame thus presents both curvature and radius such that the current confines itself to the outside of the shell with an inclination for the narrow wings and tail section, rather than the elongated body. You might be tempted to inductively tap into this frame current, but then you are on the negative, inside radius of the current carrier (makes the tube interior self-shielding). Whatever current is flowing, is on the outside of the skin, not the inside - that is, until we consider skin depth and penetration. But then it appears that experience described here suggests that not much of that frame current penetrates inside. 73's Richard Clark, KB7QHC |
Some Guy wrote:
What a load of horse ****. You guys are acting as if the engines and flight control surfaces of an aircraft are intimately tied to the plane's radio receiver, and the slightest odd or out-of-place signal that it receives is enough to send any plane into a tail spin. All this while the air travel industry is considering allowing passengers to use their own cell phones WHILE THE PLANES ARE IN FLIGHT by adding cell-phone relay stations to the planes and allowing any such calls to be completed via satellite. So I guess the feeble radiation by my FM radio (powered by 2 AAA batteries) is enough to cause a plane to dive into the ocean, but the guy next to me putting out 3 watts of near-microwave energy is totally safe. What about my hand-held GPS unit? Any chance me using it (during all phases of a flight, which I do routinely) will result in a one-way ticket to kingdom come? Too bad it's not that simple. But if you're really into this kind of argument, do a groups.google.com search of the sci.geo.satellite-nav newsgroup. There you'll find endless argument, speculation, and rationalization ranging from well informed to completely clueless. There's surely more than ample ruminating there to satisfy anyone, regardless of your orientation or clue level; it's surely not necessary to do it all over again here. Getting back to the original question (poor to non-existant AM reception), I understand the idea of aperature and long wavelenths of AM radio and the size of airplane windows - but what about the effect of ALL the windows on a plane? Don't they create a much larger effective apperature when you consider all of them? A bit larger, yes. But the attenuation inside is still very high, since the windows are extremely small and spaced very close, in terms of wavelength. Sort of like the screen of a screen room. And since the plane isin't grounded, isin't the exterior shell of a plane essentially transparent to all RF (ie it's just a re-radiator) because it's not at ground potential? No, being at "ground potential" plays no part in shielding. Currents and fields on the outside aren't magically allowed to violate basic laws of physics and migrate through a good conductor just because a shield isn't at "ground potential". For that matter, a box that is at "ground potential" at the bottom is nowhere near that potential a quarter wavelength up the side. No shield over a small fraction of a wavelength on a side could work if "ground potential" were a requirement. Yet room-sized shielded enclosures are routinely used into the microwave region. Try your own experiment. Turn your portable radio on, turn up the volume, put it into a sealed can, set it on a stool, and see how much you hear. Roy Lewallen, W7EL |
Well you have been referred to the FAA Regs and the Airline policies and
ignored them. http://www.fordyce.org/scanning/scan.../scan_fly.html http://www.airweb.faa.gov/Regulatory...e?OpenFrameSet Section 91.21 -------------------------------------------- So here is another URL we hope you read about GPS http://gpsinformation.net/airgps/gpsrfi.htm Just a snip: There are documented cases of AM/FM radios causing interference with Avionic systems and as a result, AM/FM radio receivers are generally prohibited. You will be happy to learn of this quote; "By design, (or happy accident), the "spurs" generated by a GPS generally fall outside the communications frequencies used by Aircraft and so have not been a problem even though a few "spurs" exist. But SOME airlines do not permit the use of GPS receivers. Why is that if they are "safe"?" You will be unhappy with the answers. Hope you go to the URL for the answers Here is one: If a GPS is safe, why can't I use it on an airplane anyway, even if the pilot says NO? Answer: This would be a) unwise, b) illegal and c) dangerous. Never presume that you have more authority than the Captain of a ship! He is responsible for the lives of his passengers and likely has knowledge and experience about his aircraft and/or equipment and/or this particular flight that no one else has.. The use of a GPS by a passenger is NOT worth a confrontation and a possible visitation from the police or FBI when you land.. READ THE LAST SENTENCE AGAIN Be safe, obey the law, stop guessing -- get educated and read these URL's -- RF Gotta Go SomeWhere "Some Guy" wrote in message ... What a load of horse ****. You guys are acting as if the engines and flight control surfaces of an aircraft are intimately tied to the plane's radio receiver, and the slightest odd or out-of-place signal that it receives is enough to send any plane into a tail spin. All this while the air travel industry is considering allowing passengers to use their own cell phones WHILE THE PLANES ARE IN FLIGHT by adding cell-phone relay stations to the planes and allowing any such calls to be completed via satellite. So I guess the feeble radiation by my FM radio (powered by 2 AAA batteries) is enough to cause a plane to dive into the ocean, but the guy next to me putting out 3 watts of near-microwave energy is totally safe. What about my hand-held GPS unit? Any chance me using it (during all phases of a flight, which I do routinely) will result in a one-way ticket to kingdom come? Getting back to the original question (poor to non-existant AM reception), I understand the idea of aperature and long wavelenths of AM radio and the size of airplane windows - but what about the effect of ALL the windows on a plane? Don't they create a much larger effective apperature when you consider all of them? And since the plane isin't grounded, isin't the exterior shell of a plane essentially transparent to all RF (ie it's just a re-radiator) because it's not at ground potential? |
"Some Guy" wrote in message ... What a load of horse ****. Yes, you are a wholesale distributor. Further, you are a loud-mouthed, egocentric nitwit with a knowledge of physics equivalent to a smart gerbil. You should be allowed on an aircraft only as freight. Ed wb6wsn |
So, in all honesty, YOU can't really say how dangerous operation of an FM receiver will be; but you KNOW that it's potentially harmful. Given that the aircraft voice comms are just above the FM BCB, and the typical first IF is 10.7 MHz, it's not too hard to imagine the LO sitting right on the tower comm frequency. You may only radiate a microwatt, but you're much closer to that antenna on the aircraft than the tower is. Inverse square law makes it very easy for you to win that contest. This is a pointless argument though. It's a health and safety issue, and you either follow the airline's rules, or I hope they boot you off the plane (optionally, landing first for your convenience) It is just that simple. |
(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. So in the case of an airline (air carrier) the airline makes the determination to allow, NOT the pilot. In a private plane, the pilot can decide to allow. |
That is what it says
But the average passenger wouldn't know the airline policies. If so informed with written material, most won't read them anyway. The pilot and flight attendants should know-- so asking is the reasonable thing to do. I queried several Airline pilots I know and they were all aware of their Airline policies and stated they can't give permission but could state the Airline policies and do so. AM/FM radios, GPS, FRS, GMRS, cell phones, Ham radios and other devices were included as no no's on their Airlines. Also Flight attendants are alerted to instruct passengers not to use certain portable electronic devices so listed in their airline policies. Yeah I know we are beating this thread to pieces, but maybe some readers will desist in using a $10 Chinese radio that spews RFI all over the aircraft. Yes there is room for technical argument as how dangerous some devices are. But the airlines have made their decisions based on the FAA regs. Case closed -- ID with held to protect the innocent "Dave VanHorn" wrote in message ... (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. So in the case of an airline (air carrier) the airline makes the determination to allow, NOT the pilot. In a private plane, the pilot can decide to allow. |
On Sat, 11 Dec 2004 22:23:47 -0500, "Dave VanHorn"
wrote: | | So, in all honesty, YOU can't really say how dangerous operation of an FM | receiver will be; but you KNOW that it's potentially harmful. | |Given that the aircraft voice comms are just above the FM BCB, and the |typical first IF is 10.7 MHz, it's not too hard to imagine the LO sitting |right on the tower comm frequency. |You may only radiate a microwatt, but you're much closer to that antenna on |the aircraft than the tower is. Inverse square law makes it very easy for |you to win that contest. Correct. Let me offer a slightly different but illustrative example. Since this is cross-posted to some non-ham groups, bear with me. In the 1960's I operated my amateur station on the two-meter (144 MHz) band using several hundred watts of AM and directional antennas. I'm in Tucson where we have both a commercial airport and D-M AFB. An acquaintance of mine, also a ham, was the FAA tower chief at Tucson International. One day he calls me on the phone and says that the tower guys at D-M, knowing he was a ham, called him first rather than the FCC, to report that I was interfering with their tower communications. To make an involved detective story short, it turned out that another ham, who lived just outside the AFB was using a Heathkit "Twoer". The Twoer used a super-regenerative receiver and was picking up my signal and re-radiating it on the tower frequencies. I was getting blamed for the other guy's illegal transmissions. Considering that this technology is probably used in more receivers today than any other type (garage door openers, computer wireless links, etc.) if I'm flying, I hope they are all turned off. | |This is a pointless argument though. It's a health and safety issue, and |you either follow the airline's rules, or I hope they boot you off the plane |(optionally, landing first for your convenience) It is just that simple. | |
Hey folks, let's not overdo the safety aspects here, so no one panics
if aboard an airliner and sees someone using a radio. I doubt any device emitting small RF will be able to make comm reception unreadable. Even if it did, there are then fallback procedures which the pilot is required to know by heart, and the pilot is even permitted to continue flight all the way to the gate without any communication at all. Believe it or not, other aircraft may not have to be vectored out of your way, or even informed about your problem. But in reality, the pilot would simply peek at the coffee-stained nav chart and dial up another controller on another freq and ATC will say another frequency to come up on, or "stay with me." For navigation on frequencies 108.00-117.95, besides being rather strong signals, the nature of the modulation is such that interference would have to be strong and be just so, to cause navigational error. More likely there would a panel indication of an unusable signal -- because the receiver must be designed this way, and the pilot can listen to the nav audio to hear the problem. The aircraft is also in radar contact, so that if the pilot were to wander off course -- you're allowed a fairly wide margin -- ATC tells you if outside the margin or not following a clearance if given a "direct." If you can't rectify it, you simply ask for radar vectors, or switch to GPS nav, or vice versa, or clearance to go direct to another nav beacon off the nose, or GPS direct if equipped. Now the same considerations apply to flying the approach and landing, but the pilot would rather not have to deal with potential interference to either nav or comm, especially if the airport is 1/2 mile visibility in fog. Thus, it's not too uncommon for the pilot to grant permission to use a radio device only while in cruise. Also, ATC will be able to tell the pilot that other aircraft are not reporting a problem, a hint of possible interference from inside the cabin. But has anybody ever heard a cabin announcement during flight to turn off any devices? Fred F. |
Everything you have written is probably correct BUT
That is not the point -- The FAA and Airlines have regs and policies about portable electronic equipment aboard an airliner PERIOD And yes a sharp flight attendent did tell me to turn off a GPS unit. -- ID with held to protect the innocent "TaxSrv" wrote in message ... Hey folks, let's not overdo the safety aspects here, so no one panics if aboard an airliner and sees someone using a radio. I doubt any device emitting small RF will be able to make comm reception unreadable. Even if it did, there are then fallback procedures which the pilot is required to know by heart, and the pilot is even permitted to continue flight all the way to the gate without any communication at all. Believe it or not, other aircraft may not have to be vectored out of your way, or even informed about your problem. But in reality, the pilot would simply peek at the coffee-stained nav chart and dial up another controller on another freq and ATC will say another frequency to come up on, or "stay with me." For navigation on frequencies 108.00-117.95, besides being rather strong signals, the nature of the modulation is such that interference would have to be strong and be just so, to cause navigational error. More likely there would a panel indication of an unusable signal -- because the receiver must be designed this way, and the pilot can listen to the nav audio to hear the problem. The aircraft is also in radar contact, so that if the pilot were to wander off course -- you're allowed a fairly wide margin -- ATC tells you if outside the margin or not following a clearance if given a "direct." If you can't rectify it, you simply ask for radar vectors, or switch to GPS nav, or vice versa, or clearance to go direct to another nav beacon off the nose, or GPS direct if equipped. Now the same considerations apply to flying the approach and landing, but the pilot would rather not have to deal with potential interference to either nav or comm, especially if the airport is 1/2 mile visibility in fog. Thus, it's not too uncommon for the pilot to grant permission to use a radio device only while in cruise. Also, ATC will be able to tell the pilot that other aircraft are not reporting a problem, a hint of possible interference from inside the cabin. But has anybody ever heard a cabin announcement during flight to turn off any devices? Fred F. |
TaxSrv wrote:
Hey folks, let's not overdo the safety aspects here, so no one panics [...] Fred, Nearly all aircraft accidents are caused by a series of unlikely events all happening together, none of which by itself would be a problem. Would you want to add one more "unlikely event" to your next flight? Do you have life insurance? 73, Dave (to keep this on topic, I will say this: last week my garage door snagged the corona tip on my ATAS-120 and broke something inside the tuning section, and bent my trunk lid. A $300 mistake. Damn.) |
Our club repeater also ended up interfering with the local tower.
It seems that the transmitter PLL was unstable, and "hopping" between that frequency, and ours. We were clearly audible in their recordings. Lest any "experts" step in and claim that you can't receive FM on an AM receiver, I'd ask them to consider what effect the passband filter of the AM receiver's IF might have on the FM signal as it deviates from side to side.... I hit the magic codes and took the repeater down, once we determined that this was indeed the source. A re-tweak of the transmit PLL, and a stub filter cut to pass 146.730 and reject the tower frequency, cured the problem, and insured that if it ever happens again, they probably won't hear us. The tower now has our phone numbers in their books, in case there is ever another problem. The tower complimented our rapid and assertive handling of the problem in their closing letter to the FCC. Repeater cans don't do much for signals that are far out of band. |
Our club repeater also ended up interfering with the local tower.
It seems that the transmitter PLL was unstable, and "hopping" between that frequency, and ours. We were clearly audible in their recordings. Ouch. That'd be categorized as a "double-plus ungood" for certain! Lest any "experts" step in and claim that you can't receive FM on an AM receiver, I'd ask them to consider what effect the passband filter of the AM receiver's IF might have on the FM signal as it deviates from side to side.... I believe the magic words are "slope detection". The resulting audio on the AM receiver isn't great (it's often distorted) but it's certainly there. I hit the magic codes and took the repeater down, once we determined that this was indeed the source. A re-tweak of the transmit PLL, and a stub filter cut to pass 146.730 and reject the tower frequency, cured the problem, and insured that if it ever happens again, they probably won't hear us. The tower now has our phone numbers in their books, in case there is ever another problem. The tower complimented our rapid and assertive handling of the problem in their closing letter to the FCC. Well done! -- Dave Platt AE6EO Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! |
Dave Bushong wrote:
[Dramatic generalization mode on] Nearly all aircraft accidents are caused by a series of unlikely events all happening together, none of which by itself would be a problem. [Dramatic generalization mode off] Nice sweeping piece of dis-information there buddy. How about this: Nearly all aircraft accidents are caused by a single failure in a single component or a single failure to do something. Pitot tubes that are taped over. Fuel tanks that explode. Structural failure that causes entire pieces of fuselage to peel off while in flight. Fuel leaks that turn large jets into gliders. Cabin fires caused by the overload of a single wire powering the entertainment system. Air pressure equalization valves that bleed cabin air rendering the occupants unconscious and results in a ghost plane flying thousands of miles before crashing. Failure to de-ice. Overloading resulting in stalling upon take-off. Failure to secure cargo upon takeoff. Being struck in the fuel tank by a piece of debris on the runway kicked up by the tires. An engine ingesting a flock of birds. A shipment of improperly-disarmed oxygen generators placed in the cargo hold. Lack of proper lubrication of tail jack-screws. Tail fins that are not as strongly connected to the fuselage as they should be. Need I continue? A series of events will surely happen AFTER any of those incidents, none of which are either unlikely or unexpected, and by and large would have no effect on the outcome. Will the in-flight use of an FM radio EVER cause a plane to run out of fuel? Or cause a sudden ice build-up on the wings? Or blow out a tire upon landing? Or an overload of the electrical system leading to a fire? Will the feeble RF emitted by the LO even be detectable OUTSIDE the plane, where the plane's antennas are located? If you read the various documents on the web relating to issues of in-flight use of PED's (personal electronic devices) it's clear that 1) The FAA and NTSB are either negligent or a bunch of cowards for not forcing the AIRCRAFT MANUFACTURERS to determine the level of susceptibility of their planes to PED's. Instead the issue is pawned off to the aircraft operators when logically it should be the airplane makers! 2) The use of cell phones (analog and perhaps more frequently GSM) seems to have the most influence of any PED. The next most frequent culprit seems to be laptop computers. 3) No incidence of communication failure or disruption seems to have ever been documented by a passenger's FM radio receiver. 4) MANY MANY incidences of navigation equipment errors caused by improper installation / connection of the equipment, or interference caused by one of the plane's other systems where these were first attributed to a PED. 5) Planes have to fly near high-power commercial radio and TV transmission towers. They fly through the beams of powerful radar signals. They get struck by lightning. There are those that say that for a (commercial jet) to be certified there is no way that a certified plane could be susceptible to the stray RF given off by PED's (at least PED's that are non-intentional radiators). 6) The authorities would probably not admit it, but the ban or restrictions on PED use in planes probably has more to do with insurance/liability reasons, or passenger distraction reasons, than it does for technical (interference) reasons. PED's are here to stay. There will be more of them, and people will use them wherever they are. It makes just as much sense to ban them or perform half-ass on-board supervision on a plane for these devices as it is to ban them from cars. PED's used cars cause injury and death each year (due to driver in-attention). Instead of banning radios, phones, and entertainment systems in cars, they instead come from the factory with them installed! Where's your crusade against that situation? Where are your dire warnings here? Would you want to add one more "unlikely event" to your next flight? Nothing caused by or brought on board by a passenger (short of alcohol, a gun, a bomb, or otherwise a strong intent to do harm) will or has ever caused anything bad to happen on a plane or to a plane. No gun ever brought on board (and there have been MANY!) has ever discharged. No can of hairspray has ever exploded in the cargo hold. There is relatively little variety in the types, makes or models of commercial airplanes flying today. There is a high degree of uniformity in construction of these vehicles. There have been millions of flights over the past, say 20 years. There have been many hundred million passengers carried by these planes. There surely has been ample opportunity for all sorts of PED's to be used on these planes (surreptitiously or with consent). If any particular plane model (or even specific plane) had a systemic or inherent susceptibility to a PED, it would have been recognized by now. |
Amen!
"Some Guy" wrote in message ... Dave Bushong wrote: [Dramatic generalization mode on] Nearly all aircraft accidents are caused by a series of unlikely events all happening together, none of which by itself would be a problem. [Dramatic generalization mode off] Nice sweeping piece of dis-information there buddy. How about this: Nearly all aircraft accidents are caused by a single failure in a single component or a single failure to do something. Pitot tubes that are taped over. Fuel tanks that explode. Structural failure that causes entire pieces of fuselage to peel off while in flight. Fuel leaks that turn large jets into gliders. Cabin fires caused by the overload of a single wire powering the entertainment system. Air pressure equalization valves that bleed cabin air rendering the occupants unconscious and results in a ghost plane flying thousands of miles before crashing. Failure to de-ice. Overloading resulting in stalling upon take-off. Failure to secure cargo upon takeoff. Being struck in the fuel tank by a piece of debris on the runway kicked up by the tires. An engine ingesting a flock of birds. A shipment of improperly-disarmed oxygen generators placed in the cargo hold. Lack of proper lubrication of tail jack-screws. Tail fins that are not as strongly connected to the fuselage as they should be. Need I continue? A series of events will surely happen AFTER any of those incidents, none of which are either unlikely or unexpected, and by and large would have no effect on the outcome. Will the in-flight use of an FM radio EVER cause a plane to run out of fuel? Or cause a sudden ice build-up on the wings? Or blow out a tire upon landing? Or an overload of the electrical system leading to a fire? Will the feeble RF emitted by the LO even be detectable OUTSIDE the plane, where the plane's antennas are located? If you read the various documents on the web relating to issues of in-flight use of PED's (personal electronic devices) it's clear that 1) The FAA and NTSB are either negligent or a bunch of cowards for not forcing the AIRCRAFT MANUFACTURERS to determine the level of susceptibility of their planes to PED's. Instead the issue is pawned off to the aircraft operators when logically it should be the airplane makers! 2) The use of cell phones (analog and perhaps more frequently GSM) seems to have the most influence of any PED. The next most frequent culprit seems to be laptop computers. 3) No incidence of communication failure or disruption seems to have ever been documented by a passenger's FM radio receiver. 4) MANY MANY incidences of navigation equipment errors caused by improper installation / connection of the equipment, or interference caused by one of the plane's other systems where these were first attributed to a PED. 5) Planes have to fly near high-power commercial radio and TV transmission towers. They fly through the beams of powerful radar signals. They get struck by lightning. There are those that say that for a (commercial jet) to be certified there is no way that a certified plane could be susceptible to the stray RF given off by PED's (at least PED's that are non-intentional radiators). 6) The authorities would probably not admit it, but the ban or restrictions on PED use in planes probably has more to do with insurance/liability reasons, or passenger distraction reasons, than it does for technical (interference) reasons. PED's are here to stay. There will be more of them, and people will use them wherever they are. It makes just as much sense to ban them or perform half-ass on-board supervision on a plane for these devices as it is to ban them from cars. PED's used cars cause injury and death each year (due to driver in-attention). Instead of banning radios, phones, and entertainment systems in cars, they instead come from the factory with them installed! Where's your crusade against that situation? Where are your dire warnings here? Would you want to add one more "unlikely event" to your next flight? Nothing caused by or brought on board by a passenger (short of alcohol, a gun, a bomb, or otherwise a strong intent to do harm) will or has ever caused anything bad to happen on a plane or to a plane. No gun ever brought on board (and there have been MANY!) has ever discharged. No can of hairspray has ever exploded in the cargo hold. There is relatively little variety in the types, makes or models of commercial airplanes flying today. There is a high degree of uniformity in construction of these vehicles. There have been millions of flights over the past, say 20 years. There have been many hundred million passengers carried by these planes. There surely has been ample opportunity for all sorts of PED's to be used on these planes (surreptitiously or with consent). If any particular plane model (or even specific plane) had a systemic or inherent susceptibility to a PED, it would have been recognized by now. |
"Some Guy" wrote in message ... Dave Bushong wrote: [Dramatic generalization mode on] Nearly all aircraft accidents are caused by a series of unlikely events all happening together, none of which by itself would be a problem. [Dramatic generalization mode off] Nice sweeping piece of dis-information there buddy. How about this: Nearly all aircraft accidents are caused by a single failure in a single component or a single failure to do something. Pitot tubes that are taped over. Fuel tanks that explode. Structural What is a Pitot tube anyway? I have seen a switch for most aircraft in Flight Simulator marked "Pitot Heat", what is that? |
Lots of data, not much information. No cites given.
Angry crap. Some Guy wrote: Dave Bushong wrote: [Dramatic generalization mode on] Nearly all aircraft accidents are caused by a series of unlikely events all happening together, none of which by itself would be a problem. [Dramatic generalization mode off] Nice sweeping piece of dis-information there buddy. How about this: Nearly all aircraft accidents are caused by a single failure in a single component or a single failure to do something. Pitot tubes that are taped over. Fuel tanks that explode. Structural failure that causes entire pieces of fuselage to peel off while in flight. Fuel leaks that turn large jets into gliders. Cabin fires caused by the overload of a single wire powering the entertainment system. Air pressure equalization valves that bleed cabin air rendering the occupants unconscious and results in a ghost plane flying thousands of miles before crashing. Failure to de-ice. Overloading resulting in stalling upon take-off. Failure to secure cargo upon takeoff. Being struck in the fuel tank by a piece of debris on the runway kicked up by the tires. An engine ingesting a flock of birds. A shipment of improperly-disarmed oxygen generators placed in the cargo hold. Lack of proper lubrication of tail jack-screws. Tail fins that are not as strongly connected to the fuselage as they should be. Need I continue? A series of events will surely happen AFTER any of those incidents, none of which are either unlikely or unexpected, and by and large would have no effect on the outcome. Will the in-flight use of an FM radio EVER cause a plane to run out of fuel? Or cause a sudden ice build-up on the wings? Or blow out a tire upon landing? Or an overload of the electrical system leading to a fire? Will the feeble RF emitted by the LO even be detectable OUTSIDE the plane, where the plane's antennas are located? If you read the various documents on the web relating to issues of in-flight use of PED's (personal electronic devices) it's clear that 1) The FAA and NTSB are either negligent or a bunch of cowards for not forcing the AIRCRAFT MANUFACTURERS to determine the level of susceptibility of their planes to PED's. Instead the issue is pawned off to the aircraft operators when logically it should be the airplane makers! 2) The use of cell phones (analog and perhaps more frequently GSM) seems to have the most influence of any PED. The next most frequent culprit seems to be laptop computers. 3) No incidence of communication failure or disruption seems to have ever been documented by a passenger's FM radio receiver. 4) MANY MANY incidences of navigation equipment errors caused by improper installation / connection of the equipment, or interference caused by one of the plane's other systems where these were first attributed to a PED. 5) Planes have to fly near high-power commercial radio and TV transmission towers. They fly through the beams of powerful radar signals. They get struck by lightning. There are those that say that for a (commercial jet) to be certified there is no way that a certified plane could be susceptible to the stray RF given off by PED's (at least PED's that are non-intentional radiators). 6) The authorities would probably not admit it, but the ban or restrictions on PED use in planes probably has more to do with insurance/liability reasons, or passenger distraction reasons, than it does for technical (interference) reasons. PED's are here to stay. There will be more of them, and people will use them wherever they are. It makes just as much sense to ban them or perform half-ass on-board supervision on a plane for these devices as it is to ban them from cars. PED's used cars cause injury and death each year (due to driver in-attention). Instead of banning radios, phones, and entertainment systems in cars, they instead come from the factory with them installed! Where's your crusade against that situation? Where are your dire warnings here? Would you want to add one more "unlikely event" to your next flight? Nothing caused by or brought on board by a passenger (short of alcohol, a gun, a bomb, or otherwise a strong intent to do harm) will or has ever caused anything bad to happen on a plane or to a plane. No gun ever brought on board (and there have been MANY!) has ever discharged. No can of hairspray has ever exploded in the cargo hold. There is relatively little variety in the types, makes or models of commercial airplanes flying today. There is a high degree of uniformity in construction of these vehicles. There have been millions of flights over the past, say 20 years. There have been many hundred million passengers carried by these planes. There surely has been ample opportunity for all sorts of PED's to be used on these planes (surreptitiously or with consent). If any particular plane model (or even specific plane) had a systemic or inherent susceptibility to a PED, it would have been recognized by now. |
Pitot tube at URL;
http://www.grc.nasa.gov/WWW/K-12/airplane/pitot.html Re Pitot Heat -- see URL: http://www.allstar.fiu.edu/aero/PSSI.htm Sez The system shown employs a heated pitot tube to prevent ice formation, a necessary feature for flight in instrument conditions. -- ID with held to protect the innocent What is a Pitot tube anyway? I have seen a switch for most aircraft in Flight Simulator marked "Pitot Heat", what is that? |
"Dave Bushong" wrote:
Nearly all aircraft accidents are caused by a series of unlikely events all happening together, none of which by itself would be a problem. I'll bet there's no record of a U.S. airline accident caused by faulty navigation equipment for any reason, or at least excluding maybe the early years. General aviation, yes. Would you want to add one more "unlikely event" to your next flight? I have no problem with any airline with a flat "no" policy on this, because things do happen even if rarely. NASA gathers the PED incident data, and over a 14-year period, there have been less than 100 events, mostly in cruise, most not classed as potentially serious. The reason they were reported is because the equipment told the pilot about it, and often ATC did so too. Also, NASA has to take the pilot's word for it that the anomaly was caused by a PED. Fred F. |
Dave, try these:
Boeing has investigated alleged interference from portable electronic devices (PEDs) and concluded: "As a result of these and other investigations, Boeing has not been able to find a definite correlation between PEDs and the associated reported airplane anomalies." You can look this up at: http://www.boeing.com/commercial/aer..._textonly.html Aero 10 - Interference from Electronic Devices Here's another one: http://www.rvs.uni-bielefeld.de/publ...ticle/EMI.html Electromagnetic interference with aircraft systems Dave Bushong wrote: Lots of data, not much information. No cites given. Angry crap. Some Guy wrote: Dave Bushong wrote: [Dramatic generalization mode on] Nearly all aircraft accidents are caused by a series of unlikely events all happening together, none of which by itself would be a problem. [Dramatic generalization mode off] Nice sweeping piece of dis-information there buddy. How about this: Nearly all aircraft accidents are caused by a single failure in a single component or a single failure to do something. Pitot tubes that are taped over. Fuel tanks that explode. Structural failure that causes entire pieces of fuselage to peel off while in flight. Fuel leaks that turn large jets into gliders. Cabin fires caused by the overload of a single wire powering the entertainment system. Air pressure equalization valves that bleed cabin air rendering the occupants unconscious and results in a ghost plane flying thousands of miles before crashing. Failure to de-ice. Overloading resulting in stalling upon take-off. Failure to secure cargo upon takeoff. Being struck in the fuel tank by a piece of debris on the runway kicked up by the tires. An engine ingesting a flock of birds. A shipment of improperly-disarmed oxygen generators placed in the cargo hold. Lack of proper lubrication of tail jack-screws. Tail fins that are not as strongly connected to the fuselage as they should be. Need I continue? A series of events will surely happen AFTER any of those incidents, none of which are either unlikely or unexpected, and by and large would have no effect on the outcome. Will the in-flight use of an FM radio EVER cause a plane to run out of fuel? Or cause a sudden ice build-up on the wings? Or blow out a tire upon landing? Or an overload of the electrical system leading to a fire? Will the feeble RF emitted by the LO even be detectable OUTSIDE the plane, where the plane's antennas are located? If you read the various documents on the web relating to issues of in-flight use of PED's (personal electronic devices) it's clear that 1) The FAA and NTSB are either negligent or a bunch of cowards for not forcing the AIRCRAFT MANUFACTURERS to determine the level of susceptibility of their planes to PED's. Instead the issue is pawned off to the aircraft operators when logically it should be the airplane makers! 2) The use of cell phones (analog and perhaps more frequently GSM) seems to have the most influence of any PED. The next most frequent culprit seems to be laptop computers. 3) No incidence of communication failure or disruption seems to have ever been documented by a passenger's FM radio receiver. 4) MANY MANY incidences of navigation equipment errors caused by improper installation / connection of the equipment, or interference caused by one of the plane's other systems where these were first attributed to a PED. 5) Planes have to fly near high-power commercial radio and TV transmission towers. They fly through the beams of powerful radar signals. They get struck by lightning. There are those that say that for a (commercial jet) to be certified there is no way that a certified plane could be susceptible to the stray RF given off by PED's (at least PED's that are non-intentional radiators). 6) The authorities would probably not admit it, but the ban or restrictions on PED use in planes probably has more to do with insurance/liability reasons, or passenger distraction reasons, than it does for technical (interference) reasons. PED's are here to stay. There will be more of them, and people will use them wherever they are. It makes just as much sense to ban them or perform half-ass on-board supervision on a plane for these devices as it is to ban them from cars. PED's used cars cause injury and death each year (due to driver in-attention). Instead of banning radios, phones, and entertainment systems in cars, they instead come from the factory with them installed! Where's your crusade against that situation? Where are your dire warnings here? Would you want to add one more "unlikely event" to your next flight? Nothing caused by or brought on board by a passenger (short of alcohol, a gun, a bomb, or otherwise a strong intent to do harm) will or has ever caused anything bad to happen on a plane or to a plane. No gun ever brought on board (and there have been MANY!) has ever discharged. No can of hairspray has ever exploded in the cargo hold. There is relatively little variety in the types, makes or models of commercial airplanes flying today. There is a high degree of uniformity in construction of these vehicles. There have been millions of flights over the past, say 20 years. There have been many hundred million passengers carried by these planes. There surely has been ample opportunity for all sorts of PED's to be used on these planes (surreptitiously or with consent). If any particular plane model (or even specific plane) had a systemic or inherent susceptibility to a PED, it would have been recognized by now. |
Well, I'll be flying to philly again tuesday. My dualband HT goes in my breifcase, but with the battery detached during flight. |
TaxSrv wrote: cabin. But has anybody ever heard a cabin announcement during flight to turn off any devices? Fred F. YES. I was on a flight from Toronto to Tampa a few years ago and somewhere over the Carolinas the pilot came on the PA and calmly informed us they have spent the last 45 mins trying to find the source of a buzzing noise on their radios. (He also reinforced the fact that they were all still working, but there was a buzzing noise on the audio.) He politely told everyone to turn off any electronic devices they may be using. The flight attendants quickly verified passenger compliance a few minutes later. About 10 mins after that, he came on the PA to say it was gone and instructed everyone to leave them off for the duration of the flight, not that there was any danger, but it was distracting to have a constant buzzing coming over the radio. I did notice a couple of laptops had been fired up, but sitting in your seat is not exactly an ideal vantage point to see what everyone else was doing. Do I think someone's radio is going to make the plane fall from the sky? Of course not. Is there a remote possibility it could cause birdies or other RF anomalies that 'could' affect things? Sure. On one flight, a few years earlier still, WITH the ok from the flight deck (you know, in those friendlier years when you could say 'hi' through the open cockpit door when you were coming out of the bathroom) I used my FT-470 handie for a few mins. The pilot knew what ham radio was, knew I was going to be on UHF (because I told him that's where I would try for a quick QSO) and he very politely said "Sure, but only for 5 minutes, then turn it off. What seat are you in?" I thanked him kindly, returned to my window seat, and did manage to get into some repeater in Maine for about a minute or two. The funny thing was he was in the galley as we were getting off the plane, I thanked him again, and he asked if I had any luck, I said 'yep' and asked him if I came over anything up front. He smiled and said "Nope, and we were up there looking to see if you would." The purpose of my sharing this snippet from many years ago is not to illustrate there's no danger in using a receiver (or in this case, a low power transmitter) while on a plane, but using one does not automatically imply you're going to write off the comm/nav systems. My $.02 |
"TaxSrv" wrote in message ... Hey folks, let's not overdo the safety aspects here, so no one panics if aboard an airliner and sees someone using a radio. I doubt any device emitting small RF will be able to make comm reception unreadable. Even if it did, there are then fallback procedures which the pilot is required to know by heart, Your doubts do not stand up to empirical evidence. Stick to assertions that have a basis in fact and not just in your mind. The whole point is to not weaken the chain of redundant flight safety features just to allow a piece of meat cargo to be electronically entertained. Now the same considerations apply to flying the approach and landing, but the pilot would rather not have to deal with potential interference to either nav or comm, especially if the airport is 1/2 mile visibility in fog. Thus, it's not too uncommon for the pilot to grant permission to use a radio device only while in cruise. And all passengers will immediately comply, because they are all concerned about not creating a dangerous electronic environment. Games will be halted, spreadsheets closed, and porn movies terminated. Cabin attendants will notice immediate 100% compliance, and will not be distracted from other duties to repeatedly remind, cajole or threaten recalcitrant passengers. Fred, your world is much different than any I have ever seen. Ed wb6wsn |
"Some Guy" wrote in message ... Dave Bushong wrote: [Dramatic generalization mode on] Nearly all aircraft accidents are caused by a series of unlikely events all happening together, none of which by itself would be a problem. [Dramatic generalization mode off] Nice sweeping piece of dis-information there buddy. Will the in-flight use of an FM radio EVER cause a plane to run out of fuel? Or cause a sudden ice build-up on the wings? Or blow out a tire upon landing? Or an overload of the electrical system leading to a fire? Will the feeble RF emitted by the LO even be detectable OUTSIDE the plane, where the plane's antennas are located? It's so damn complicated that nobody can answer the question. Airliners are going in the direction of all-electronic flight control and management systems. Somebody's LO won't affect fuel consumption, uhh, unless it affects the microprocessor or sensors controlling the engine. It's unlikely, a lot of work goes toward making it extremely unlikely. But remember, I said unlikely, not impossible. Ice on the wings? What controls the de-icing boot? Blow a tire? Is the braking circuit all-mechanical, or do you have something akin to power boost and anti-lock sensing? Is the LO detectable outside the fuselage, near the antennas? YES, damn it, YES. I have measured it, with calibrated field strength meters. Don't give me your damn dumb opinions when I have seen the results myself. And is the LO emission strong enough to degrade or deny a navcom signal. YES or MAYBE or COULD BE. It depends on the passenger's radio, how he holds it, is he next to a window, is the fuselage unusually leaky to RF, what seat is the passenger in, what station is the radio tuned to, are the batteries new or weak, how weak is the navcom signal, what is the attitude of the aircraft, is the navcom receiver getting old, even are there multiple passenger receivers acting on the navcom (if they are all like you, how many of 300 passengers will have personal electronics running?). The POSSIBILITY of interference is undeniable. The PROBABILITY is very difficult to predict. The safe course is to deny you your entertainment for several hours to ensure maximum safety. Is that too much to ask of you? Ed wb6wsn |
"chuck" wrote in message nk.net... Dave, try these: Boeing has investigated alleged interference from portable electronic devices (PEDs) and concluded: "As a result of these and other investigations, Boeing has not been able to find a definite correlation between PEDs and the associated reported airplane anomalies." You can look this up at: http://www.boeing.com/commercial/aer..._textonly.html Aero 10 - Interference from Electronic Devices Here's another one: http://www.rvs.uni-bielefeld.de/publ...ticle/EMI.html Electromagnetic interference with aircraft systems Not to cast aspersions on Boeing research, as they are quite reputable, but if they had found correlatable evidence of PED's interfering with avionics, who gets sued? The passenger, a Hong Kong radio manufacturer, or the aircraft builder? In any case, the reports of interference keep coming in, despite the difficulty of replicating the problem. Obviously, the problem is rare and elusive, but, as in most Electromagnetic Compatibility issues, the easiest, surest, and cheapest cure is to control the source of the problem. Just turn off ALL passenger electronics for the duration of the flight. Read a book for 2 hours, and let your kid kick the seat in front of him. Ed wb6wsn Ed wb6wsn |
"Dave VanHorn" wrote in message ... Well, I'll be flying to philly again tuesday. My dualband HT goes in my breifcase, but with the battery detached during flight. The first note of personal responsibility and common sense yet seen in this thread. Congratulations! Ed wb6wsn |
"Ed Price" wrote:
... Stick to assertions that have a basis in fact and not just in your mind. ... Fred, your world is much different than any I have ever seen. Ed wb6wsn My world is as an instrument rated pilot and one who services aircraft avionics. And you must have missed my other post where I said PEDs should be off at all times. Fred F. |
"phoneguy99" wrote in message .. . TaxSrv wrote: cabin. But has anybody ever heard a cabin announcement during flight to turn off any devices? Fred F. YES. SNIP On one flight, a few years earlier still, WITH the ok from the flight deck (you know, in those friendlier years when you could say 'hi' through the open cockpit door when you were coming out of the bathroom) I used my FT-470 handie for a few mins. The pilot knew what ham radio was, knew I was going to be on UHF (because I told him that's where I would try for a quick QSO) and he very politely said "Sure, but only for 5 minutes, then turn it off. What seat are you in?" I thanked him kindly, returned to my window seat, and did manage to get into some repeater in Maine for about a minute or two. The funny thing was he was in the galley as we were getting off the plane, I thanked him again, and he asked if I had any luck, I said 'yep' and asked him if I came over anything up front. He smiled and said "Nope, and we were up there looking to see if you would." The purpose of my sharing this snippet from many years ago is not to illustrate there's no danger in using a receiver (or in this case, a low power transmitter) while on a plane, but using one does not automatically imply you're going to write off the comm/nav systems. My $.02 It also illustrates the safety concern. Although there were no observed improper responses from the aircraft avionics, "we were up there looking to see if you would" (cause a problem) is very disturbing. You added to the pilots' workload for several minutes, involving them in an interesting science project. The cockpit is normally a very busy place, so what tasks were slighted to allow time for your project? How would you have felt if the flight crew was diverting some of their time to help somebody with a tough crossword puzzle? Was a Maine QSO worth it all? I'd have given you a whole quarter to pull the battery from your HT! Ed wb6wsn |
Years ago I was flying in a friends private plane. I used a Ht on 146.52 to
make some contacts. My friend announces that we are lost. It took about 10 minutes before I found a landmark and got him following a road to the airport. My friend believes that the HT interfered with his radio compass and put use off course. After the HT was turned off and time was allowed, the compass returned to normal. I don't know how it happened, but it did! Now I just carry my ht on the plane and do not operate! Randy ka4nma |
|
'Course, he was also a ham and we were flying in a sailplane that had a couple of light bulbs for electronics. [g] The only way to fly. Well, if one of the light bulbs goes out, they'll blame it on the nearest ham :) Seems pretty safe, but I still wouldn't do it without permission. I'm like that when I drive. I'm in the left seat, it's my car and my ass, and I make the decisions. I have actually had a passenger throw a fit because I wouldn't make a left turn that I wasn't convinced was safe, in the 1-2 seconds I had to look at it when the passenger hollered "turn left here". He got to walk home. |
Some Guy wrote:
"I have no trouble receiving FM radio broadcasts on a small am/fm radio I sometimes listen to while onboard commercial jet sirliners (flying at cruise altitude), but I bever seem to be able to pick up AM radio stations. It`s just static across the AM band. Any explanation for this?" Fuselage of the airliner acts as a waveguide below cutoff frequency (where diameter is at least 1/2-wavelength). Below cutoff, attenuation soars rapidly. FM wavelength is about 3 meters. AM wavelength is about 300 meters. Propagation of FM inside the fuselage is OK. Propagation of AM inside the fuselage vanishes quickly. You need to stick the suction cups of your Zenith portable`s Wave Magnet to a window to get AM reception. Best regards, Richard Harrison, KB5WZI |
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