 celeritypcFor Lucky Best Wash, Use Mr. SparklePremium
join:2004-05-15
Caldwell, NJ | The real issue is... It's not so much the fact that cell phones are obnoxious in flight--they are. The real issue is that airplanes use very thin wire that is not shielded to reduce the overall weight of the aircraft. Because of this, the signals or electricity sent over those wires are sent at very high frequencies--much higher than the 60 hz of standard household current. These frequencies are the same as used for wireless communication. That is why there is an issue with wireless communication devices on a plane, specifically, radios, tvs, cellphones and such. Other electronics such as laptops, mp3 players and video games don't cause a problem.
The reason they ban the use of all electronics during take-off and landing is more of a safety issue--if there is a problem, you will be able to hear the flight crew rather than being buried in your laptop or music. |
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 peter_mPremium
join:2005-07-13
Canada, QC
2 edits | Seriously, you really believe tens of tonnes of machinery cant accommodate one hundred pounds for the extra weight of the shielding?
EDIT: Modern phones have smaller transmitters but what about the older ones? They packed a punch in terms ow watts and I never heard of a plane crash caused by someone leaving a cell phone switched on. |
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 DHRacerFire Survivor
join:2000-10-10
Lake Arrowhead, CA
 ·Charter
 ·Verizon Online DSL
| reply to celeritypc
Don't new civilian aircraft (Beoing 777 and Airbus' equivalent) use ODN? (Optical Data Networks)
I'd imagine that fiber as a means of signal transmission is probably lighter than any insulation covered copper wire.
I thought fly-by-light was already in use in civilian applications? I know the military already uses it.
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"No one will believe you solved this problem in one day! We've been working on it for months. Now, go act busy for a few weeks and I'll let you know when it's time to tell them." (R&D Supervisor, Minnesota Mining & Manufacturing /3M Corp.) |
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 mazhurgPremium
join:2004-05-02
Portage La Prairie, MB
·MTS
| reply to celeritypc
said by celeritypc:It's not so much the fact that cell phones are obnoxious in flight--they are. The real issue is that airplanes use very thin wire that is not shielded to reduce the overall weight of the aircraft. Because of this, the signals or electricity sent over those wires are sent at very high frequencies--much higher than the 60 hz of standard household current. These frequencies are the same as used for wireless communication. That is why there is an issue with wireless communication devices on a plane, specifically, radios, tvs, cellphones and such. Other electronics such as laptops, mp3 players and video games don't cause a problem. The reason they ban the use of all electronics during take-off and landing is more of a safety issue--if there is a problem, you will be able to hear the flight crew rather than being buried in your laptop or music. I call it.
This ranks right up there with the big scare that normal cell phone operations can cause explosions while refuelling.
Cell phone frequencies are operating in reserved frequencies that *are* different than those from instruments. Basic navigation instruments operate in the AM/FM band, military navs operate at UHF frequencies. GPS operates nowhere near cell freqs. About the only device that can interfere are satellite phones as they are near GPS and normally operate at powers high enough to cause cross freq bleed.
Most aircraft control wiring is high voltage and *is* shielded as there are much more powerfull signal emiting devices than cells right on the plane flight paths on take offs and landings that could cause interference. (ILS/MILS/VOR/TACAN/Low/Mid/High beacons and others).
At most, the problem is made up as while the study found that there was cell chatter, they never did find nor heard of actual issues deriving from them during the study. However, because they found that people where using their cells in flight critical moments they jumped to conclusions that it might be harmfull if the signal might interfere. And an infinite number of monkeys on typewriters can also write novels...
Nothing to see here but another attempt at pushing a profitable status quo by funding a flawed study. |
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RadioDoc58ef2c0Premium,ExMod 2000-03
join:2000-05-11 | reply to celeritypc
Wow. You might want to go back to elementary avionics 101 because what typed there is totally wrong.
The power on most aircraft is 400 Hz AC. It is 400 Hz (and not 60 Hz) so that the transformers and other electromagnetic parts in the various equipment can be lighter (among other reasons). It has nothing to do with the wire sizes used.
No wireless communications system I know of operates at 400 Hz.
Cell phones can (and sometimes do) malfunction and transmit off frequency spurious emissions, and since the very low power 1.5 GHz GPS signals are sitting in the middle of two bands used for cell service they are easily disturbed by a device transmitting crap at those frequencies.
Same thing applies with radio and TV receivers. They have local oscillators and do radiate RF signals under normal use, sometimes quite strong ones, through their antennas.
Laptops, MP3 players, etc., generate and use radio frequencies but tend to be less of a radiator.
The ban at takeoff and landing is all about not jamming navigation and communications equipment with on-frequency signals.
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Toolmaster of La Grange. |
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mazhurgPremium
join:2004-05-02
Portage La Prairie, MB Reviews:
·MTS
| said by RadioDoc:Cell phones can (and sometimes do) malfunction and transmit off frequency spurious emissions, and since the very low power 1.5 GHz GPS signals are sitting in the middle of two bands used for cell service they are easily disturbed by a device transmitting crap at those frequencies. As far as I know, GPS navigation is still not approved for critical phases (at least as of a few years ago, no longer current) and for in-flight point to point redundancy is built into the system(s).
The closest cells frequencies operate is about 350MHz away, which is a fair way to go freq wise. |
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| reply to celeritypc
If the cable is not shielded, the flightworthiness certificate should be immediately revoked.
Here's a hint: in every test to date where "interference" has been reported in lab conditions, either the receiving unit was faulty or the cabling, antenna, or ground plane was faulty or not correctly installed. "bare wires" in an aircraft will not pass a (legitimate) inspection and would result in the aircraft being grounded. This is true even of experimental/homebuilt aircraft. The FAA will not let you fly.
A sport aircraft? They're strictly VFR, and sure, you can not deal with annual inspections and can fly with bare wiring, but you also are very restricted in where amd when you can fly. Ultralights? I've not seen any ultralights with instrumentation, but no ultralight will ever be flying IFR anyhow.
It's all about economics. |
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| reply to celeritypc
Fact is fact, and celeritypc is correct about shielding. The shielding that exists on newer aircraft/avionics (navigation/communication) equipment is better, but is easily compromised over the life of the plane. Shielding on older aircraft can be completely non-existent.
How many of you know RF well enough to confidently say that while the flight crew is shooting a CAT III approach (basically NO visibility) in blinding fog that cell phone RF isn't toying with the autoland system? |
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