What kind of electronics can I use on an airplane?

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[folks, we've been spammed - shuwang who started this thread embedded a spam link into his signature so I've deleted his post that started this and then just quoted his message here - cliff]

shuwang wrote:
When the flight attendant say, "You may now use your electronics," what kind of electronics can I use? Can I use a phone? If I had an iPhone, could I be able to use the internet or something? And why aren't you allowed to use electronics sometimes when you fly on a plane anyway?

most of the major airlines have guidlines on their websites. Mobile phones will most likely have problems working at the cruising height and speed of an airliner due to doppler effect.

Takeoff and landing are crucial phases, so they want to avoid potential interference from electronic devices so that's why they ask you to turn them off. Personally I don't want the plane I'm on to crash.

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You are not allowed to use any kind of device with a radio transmitter or receiver. Some aircraft companies allow phones that have a flight-mode. Flight-mode meaning no internet access.

Takeoff and landing is extra crucial, close to ground means smaller margins if something happens, and therefore you are not allowed to have any electronic devices turned on. And if something happens, they don't want your device to fly around in the cabin either.

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Sad to say Ryanair between London and Dublin have an on-bard GSM cell that then relays via satellite so they are the exception to the rule and are planes where you can use GSM during a flight - but this is only in the cruise, not during the climb or descent.

When the coming of this was discussed on the radio here a scientist pointed out that on a plane holding 100-120 people there are generally always at least 5 mobile phones (usually inadvertently) switched on. This seems to suggests that mobiles do not actually pose that much danger or they'd have been doing more about this already. On the other hand I'm outraged when someone blatantly has one switched on when they've been told not to.

These days they say you can play handheld games consoles and MP3 players once in the cruise though I wonder if they realise that, for example, Creative and Apple players have Wi-Fi transmitters in them.

The thing that really bugs me is that they generally say that you cannot use GPS at any stage during the flight (and I guess this is more so since Christmas Day). But a GPS is only a receiver, not a transmitter?

Cliff

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The good thing about having a GPS cell on the plane is that all phones that are on are sending at lowest possible power since the cell is so close.

I always also wondered why receivers are not allowed. I was thinking three options. Either if the device fails it might start sending instead of transmitting. Or an receiving antenna might also interfere with radio equipment. Or the just don't want you to listen to the radio communication to and from the pilots. If something happens or if the person listening misunderstand something it could cause panic aboard.

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Don't some aircraft have a channel on the on-board entertainment system on which you can listen to the radio communications of the pilots?

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Quote:

Don't some aircraft have a channel on the on-board entertainment system on which you can listen to the radio communications of the pilots?

Sadly not nearly enough. I guess I must have flown more than 500 times in my life and yet I only ever experienced this on one aircraft doing an internal flight from SFO to LAX

At least modern Boeings generally have the telemetry on video channel 15/17 to keep us aviation enthusiasts entertained (though it's always turned off too soon during the approach - which is the most interesting phase of the flight). After Christmas Day they are now going to stop making this feature available though as they don't want the bomber with C4 in his underpants to know where the plane is in order to detonate at the most destructive point - maybe this is also the reason for ban on GPS receivers - though this was long before the Christmas Day incident in Detroit.

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Quote:

The good thing about having a GPS cell on the plane is that all phones that are on are sending at lowest possible power since the cell is so close.

You did mean to say "GSM" didn't you?

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clawson wrote:

When the coming of this was discussed on the radio here a scientist pointed out that on a plane holding 100-120 people there are generally always at least 5 mobile phones (usually inadvertently) switched on. This seems to suggests that mobiles do not actually pose that much danger or they'd have been doing more about this already. On the other hand I'm outraged when someone blatantly has one switched on when they've been told not to.

It's an aerospace thing; they tend to ban anything considered possibly harmful unless proven otherwise.

As they've got no chance of certifying every phone (and firmware) that hits the market, it's easier for CASA/CAA/FAA just to ban them outright.

Unintentional jamming is also possible, At one stage, we had a (non-aerospace) product that passed FCC EMC testing, but jammed GPS at very close ranges - there happened to be a really small harmonic smack bang in the middle of GPS L1, but it coupled onto something and bob's your uncle, a new hardware revision was necessary.

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JohanEkdahl wrote:
Quote:

The good thing about having a GPS cell on the plane is that all phones that are on are sending at lowest possible power since the cell is so close.

You did mean to say "GSM" didn't you?
Ah, yes! I did mean that.

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I'm very cynical about this. Same about not using a mobile phone in a petrol station. If phones transmitted signals that could "interfere" with the vital components on a plane, don’t you think that would be dangerous for the plane when it took off ?! Climbing over built up area, full of people with mobile phones and right over the top of mobile aerials. Is there a shred of evidence that there is anything on a plane that is "interfered" with by a mobile phone ... or for that matter a single case of a petrol ignition from a mobile phone !? If there is, they should ban cheap clothing in petrol stations too ... I've had countless shocks of people with nylon jumpers and nylon shoes, but never from a mobile phone user !?
:-)

Jon.

Jon Russell

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My impression is that cell phones are also banned for a second reason:

Original cell phones were 3W 800MHz. As the number of cells have increased, analog has gone digital, and comm methods have changed, the power of the Tx has markedly decreased. Max of 300 mW TX power was common a few years ago, and the power is significantly lower, typically, these days, when one is surrounded by cells.

At low power one can typically hit a few cells. The cell can tell your phone to decrease its power level so you don't bleed over into too many adjacient cells.

In the analog days, when you "owned the channel" when you were on the phone, while airborne your phone could hit MANY Many cells. (Great antena location, 30K ft!). You effectively blocked that channel on MANY cells, not just the primary cell you were communicating through. It was not uncommon to occassionally hear "cross channel" interference, which wasn't really cross channel at all!

With digital transmissions these day, the pseudo cross channel interference is gone, you are not likely to hear the other user in an inteligible manner, but the transmission still counts as noise. This degrades the S/N for your transmissions on the ground, and the cell tells you to use higher power. This then provides increased noise on adjacient and nearby cells, etc.

The primary reason, however, is the avoidance of EMI sources compromising the Navigation, Communications, and Flt Control systems on the aircraft. Getting medical instrumentation authorized for on aircraft use can be a real hassel!

JC

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Yeah, but then if a single accident occurs related to a cell phone in either a fueling station or on an airplane, and they weren't banned to begin with, the company who did not ban them in the first place are open to lawsuits. It has nothing to do with whether or not there is a real risk, it has to do with how much court money your life is worth if the plane goes down.

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JC,

My GSM phone is capable of hitting 33dBm, which is 2 watts! At five miles high, surrounded by a big metal wall to block the signal, I think that there is a good chance of hitting the upper limits. On board femtocells will keep the transmission power of the phones down to an absolute minimum.

With aerial phones; the networks on the ground can experience problems as it great deal of unnecessary signalling can occur as the phone hops between the many GSM towers that it can see.

Cliff,

Funny how it is the low cost airline such as Ryan Air that have femtocells on planes - I've not seen one on any Delta, BA or Virgin flight that I have taken yet...

-Tim

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The ban is not just cell phones. PDAs, games, etc, are all included. The reason? They all have oscillators. Microprocessor clock signals are a big concern. Voice and VOR (directional information) is all in the 108-128MHz band (plus some frequencies a bit higher); a 16MHz clock can easily have a harmonic that falls right in that band.

Generally, in-flight, most commercial aircraft now rely heavily on GPS and inertial navigation. These tend to be pretty immune with respect to interfering signals. But, landing is the big one. It relies on VHF/UHF ground based amplitude modulated signals. All it takes is a little "beat note" on a localizer or glide slope signal, and the pilot has problems that are not obvious in the cockpit. Hence, the "better safe than sorry" policy.

Jim

 

Until Black Lives Matter, we do not have "All Lives Matter"!

 

 

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Quote:

Cliff,

Funny how it is the low cost airline such as Ryan Air that have femtocells on planes - I've not seen one on any Delta, BA or Virgin flight that I have taken yet...


Ryanair is run by a very charismatic gentlemen called Michael O'Leary - it's rumoured that his first money making venture involved selling black pudding made from blood extracted from stones ;-)

(He's even toying with the idea of charging €1 to use the toilet on board his aircraft!)

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clawson wrote:
Quote:

Cliff,

Funny how it is the low cost airline such as Ryan Air that have femtocells on planes - I've not seen one on any Delta, BA or Virgin flight that I have taken yet...


Ryanair is run by a very charismatic gentlemen called Michael O'Leary - it's rumoured that his first money making venture involved selling black pudding made from blood extracted from stones ;-)

(He's even toying with the idea of charging €1 to use the toilet on board his aircraft!)

Soon he'll be selling orange juice extracted from his passengers.

/Jesper
http://www.yampp.com
The quick black AVR jumped over the lazy PIC.
What boots up, must come down.

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I suspect that the reason he hasn't started charging for the smallest room is that he hasn't come up with a way to evict a passenger from there... after all, it has more elbow and leg room than his seats in the main cabin, so once you're in there, there's no real reason to leave until it's time to land.

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But the clever marketeer will just see that as an opportunity:

"Seat upgrades only €1!"

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You guys crack me up ...

Thanks,

Ross

Ross McKenzie ValuSoft Melbourne Australia

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Quote:

You guys crack me up ...

Oh! We haven't seen him around here for a long time. Not since Sep 30, 2008 in fact.

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No guarantees, but if we don't report problems they won't get much of  a chance to be fixed! Details/discussions at link given just above.

 

"Some questions have no answers."[C Baird] "There comes a point where the spoon-feeding has to stop and the independent thinking has to start." [C Lawson] "There are always ways to disagree, without being disagreeable."[E Weddington] "Words represent concepts. Use the wrong words, communicate the wrong concept." [J Morin] "Persistence only goes so far if you set yourself up for failure." [Kartman]

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shuwang wrote:
When the flight attendant say, "You may now use your electronics," what kind of electronics can I use? Can I use a phone? If I had an iPhone, could I be able to use the internet or something? And why aren't you allowed to use electronics sometimes when you fly on a plane anyway?

It varys by airline, country, phase of the moon. In truth there is not much substance to the claims that interference might occur. I don't have the list in front of me at the moment, but in general, if it has an intentional transmitter, you can't use it. In addition UHF/VHF scanning receivers are forbidden. GPS receivers with an integral antenna are OK, external antenna, no. On those aircraft with WiFi you can obviously use your computer and surf the net in flight. This, despite the fact that there is no way every laptop computer and its associated WiFi have been tested for EMC with every model aircraft. Not to mention the intermod going on with 50 or so folks all logged on at once.

The only EMC I have experienced in my 30 year aviation career has been the occasional spur camped out on one of the VHF ATC frequencies. That's annoying, but generally not strong enough to block ATC transmissions. I can usually switch transceivers and that fixes it, since one antenna is on the belly and the other on the roof.

Really, if EMC was much of a problem the landscape would be littered with aircraft because the rule is ignored on a regular basis by passengers who think it applies to everybody else.

Greg

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Recent flight on Delta in the US - WiFi servce aboard. Above 10,000 ft.

BTW: GSM and TDMA cell phones are much, much higher powered than CDMA (Sprint/Verizon in the US) - due to the very nature of CDMA.

Worst cell phone of all is Nextel iDEN, for excessive transmitted power.

Worst of any is a ReFlex two-way pager, in radiated power.

But all of these are such a low duty cycle that human tissue damage seems, by consensus, to be unlikely.

If you're paranoid, don't live near a broadcast station's transmitter. That's a bonafide worry. Along with microwave ovens with leaky door RF gaskets.

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And that is nothing compared to the beamed microwaves satellite TV broadcasters bombard us all with 24/7. Then they go and say cancer is the result of eating MSG's...

Sigh.

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Quote:

eating MSG's...

:lol: Ho, ho. I mis-read that as "eating SMG's" - now THAT would be deadly.

(Me, I like a nice bit of umami flavour enhancing though and sod the consequences)

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UNiXWHoRe wrote:
And that is nothing compared to the beamed microwaves satellite TV broadcasters bombard us all with 24/7. Then they go and say cancer is the result of eating MSG's...

Sigh.

Those TV satellites at 22,000 miles away produce a completely harmless signal strength on the ground. Read up on the inverse square law in RF propagation.

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Meh, who is to say it is harmless? I know this will sound tinfoil-hat-ish, but the only recent studies I have seen on this subject were paid for by big satellite TV companies. It might be harmless for a minute or an hour, but I highly doubt any study whatsoever was made on the health hazards of long-term low power microwave radiation on the human body. I think the only studies I caught a glimpse from were made from Soviet scientists during the cold war and it was determined to cause cancer in particular in tissues with lower blood flow.

But what do I know... Point is even if there was a risk, no one would be willing to part with their satellite TV, or cell phone. Lobbyists would certainly not let any such studies go to the general public.

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I'm guessing, with TSA and the like, you'll not be allowed anything you make as a Freak

If you don't know my whole story, keep your mouth shut.

If you know my whole story, you're an accomplice. Keep your mouth shut. 

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Sadly I know more about Astra 2A at 28.2degE that I'd really want to:

http://www.ses-astra.com/busines...

I fail to see how 98W of 11GHz microwave broadcast 22,000 miles away could ever be considered harmful? It takes almost 1m^2 concentrating the received signal to even gather enough for acceptable reception using a very sensitive Low Noise Block.

I'd look closer to home - a couple of W about 2cm from your left lughole if 0.9/1.8GHz radiation is a concern.

Or leakage from the 2.45GHz that cooks your evening meal.

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FYI:

http://www.caa.co.uk/docs/33/CAPAP2003_03.PDF
http://www.caa.co.uk/docs/33/CAP756.PDF
http://www.boeing.com/commercial/aeromagazine/aero_10/interfere_story.html

When I'm doing an ILS approach, I make sure all phones are off. But that's just me. I don't want to land on the taxi way :)

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UNiXWHoRe!

Take the 98 Watts that Cliff has stated, and the 22,000 miles. Then assume that the largest area your brain can "expose" facing the satellite is eg 2 decimetres square. How many watts will that be?

You are simply computing

22 Watts * area-of-surface-of-sphere-with-radius-22000miles / 2-decimetres square

make sure the two areas have the same unit (ft^2, or m^2 or...)

Even multiplied with 100 (for that many satellites) I'm sure I have a lot more radiation sources much closer to me, so I wont bother computing it. I'll walk the dog instead.

EDIT: And, of-course the transmission from the satellite is directed, so the radiation that hits your brain will be bigger than just the simple "inverse square" calculation. Times 100?

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No guarantees, but if we don't report problems they won't get much of  a chance to be fixed! Details/discussions at link given just above.

 

"Some questions have no answers."[C Baird] "There comes a point where the spoon-feeding has to stop and the independent thinking has to start." [C Lawson] "There are always ways to disagree, without being disagreeable."[E Weddington] "Words represent concepts. Use the wrong words, communicate the wrong concept." [J Morin] "Persistence only goes so far if you set yourself up for failure." [Kartman]

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The satelite signals are really weak. One TV signal is direkted at an area of about 1000 km in diameter. So per square meter one has about 100 W * 1 m² / (10^12 m²) = 0.1 nW.

One can get more power from mocrowave ofens, military radar, aviation radar, wether radar and similar.

The trouble the soviet and east german military (to a lesser extend also in the west) had with military radar stations was due to X-ray emmisons. The radar signal is gerated from high voltage vacuum tubes that also produce some X-rays and these can cause cancer.

If a plane has no special local node for the mobile phones, there will be no good reception inside anyway. So why should they allow the phones to be on and pose a small risk to cause EMI. Especially GSM phone have really high peak power if they have no contact to a ground station. So having the pico cell inside the plane is a good idea to minimize EMI. Usage will not be that heavy due to high roaming costs anyway.

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Kleinstein wrote:
So per square meter one has about 100 W * 1 m² / (10^12 m²) = 0.1 nW.

You can do the math, articulate the logic, but the left-wing wackos and conspiracy-theory types ignore it all and prefer to make theater of it.