Power Down in Airplanes

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Leesbro63
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Power Down in Airplanes

Post by Leesbro63 »

What is the reason behind required electronics power down on commercial flights?
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burgrat
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Re: Power Down in Airplanes

Post by burgrat »

The flight attendants want your undivided attention.
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Re: Power Down in Airplanes

Post by nisiprius »

Radio frequency interference (RFI). As it is, the built-in electrical data systems in a modern airplane generate so much RFI and are so closely packed that it is an engineering issue to make sure that they don't interfere with each other. I've read that this is actually a serious issue in military spy planes that are densely crammed full of high-tech gear.

"Portable electronic devices," particularly those that are supposed to be transmitting radio waves, generate RFI. The speakers of my wife's computer makes a funny little crackling beep every so often if she's wearing her cell phone nearby; something from the phone is creating interference, probably directly in the speaker audio input circuits. And somewhere there was a video on YouTube of someone demonstrating a case in which he could make a server crash by making a call from his cell phone in the same room.

Very likely it isn't all that dangerous but the airlines don't particularly want to count the number of WiFi-enabled devices on the plane, or read labels on them to determine which are old-fashioned high-powered analog phones or whatever... or discover that the very-latest-generation thingies run at a different frequency than the old ones.
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Re: Power Down in Airplanes

Post by nisiprius »

As is so often the case, Google found me a very good Wikipedia article, Mobile phones on aircraft..
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Re: Power Down in Airplanes

Post by chaz »

Would an iPad have to remain turned off while in flight? It does have a setting for in flight usage.
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Re: Power Down in Airplanes

Post by Sidney »

chaz wrote:Would an iPad have to remain turned off while in flight? It does have a setting for in flight usage.
Only during the usual power-ban during take off and landing. I have a Kindle but I always take a paperback on planes -- can sometimes be on the tarmac a long time.
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Re: Power Down in Airplanes

Post by chaz »

Thanks, Sidney.
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hicabob
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Re: Power Down in Airplanes

Post by hicabob »

...and please remove the batteries from those electric watches too - all that rfi you know - another advantage of $5k rolexes - they don't cause planes to drop out of the sky!
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Re: Power Down in Airplanes

Post by ThatGuy »

From this report by Boeing:
Boeing wrote:Some sample cases are included here to illustrate the variety of potential PED events.

1995, 737 airplane.
A passenger laptop computer was reported to cause autopilot disconnects during cruise. Boeing purchased the computer from the passenger and performed a laboratory emission scan from 150 kHz to 1 GHz. The emissions exceeded the Boeing emission standard limits for airplane equipment at various frequency ranges up to 300 MHz. Boeing participated with the operator on two flight tests with the actual PED, using the same airplane and flight conditions, in an attempt to duplicate the problem. Using even these extensive measures to re-create the reported event, Boeing was unable to confirm the reported interference between the PED and the airplane system.

1996/1997, 767 airplane.
Over a period of eight months, Boeing received five reports on interference with various navigation equipment (uncommanded rolls, displays blanking, flight management computer [FMC]/ autopilot/standby altimeter inoperative, and autopilot disconnects) caused by passenger operation of a popular handheld electronic game device. In one of these cases, the flight crew confirmed the interference by turning the unit on and off to observe the correlation. The same unit was used on another flight and on a different airplane, but the event could not be duplicated. Boeing purchased two of the actual suspect units through the airline and tested them in the laboratory, along with three off-the-shelf units. It was determined that these suspect units had emission profiles similar to the off-the-shelf units and that the levels from these devices were below airplane equipment emission limits.

1998, 747 airplane.
A passenger’s palmtop computer was reported to cause the airplane to initiate a shallow bank turn. One minute after turning the PED off, the airplane returned to "on course." When the unit was brought to the flight deck, the flight crew noticed a strong correlation by turning the unit back on and watching the anomaly return, then turning the unit off and watching the anomaly stop. Boeing was not able to purchase the actual PED, but contacted the PED manufacturer and purchased the same model. Boeing laboratory emission testing revealed that the unit exceeded Boeing airplane equipment emission levels by up to 37 dB by demonstrating energy levels in the frequency range of 150 to 700 kHz. In the Boeing navigation laboratory the unit was placed next to the FMCs, control display unit, and integrated display unit, but the reported anomaly could not be duplicated.

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.
http://www.boeing.com/commercial/aeroma ... tonly.html
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Re: Power Down in Airplanes

Post by The Wizard »

ThatGuy wrote: 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.
It's mostly fear of the unknown, correct.
Nothing much to do with engineering science.
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Epsilon Delta
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Re: Power Down in Airplanes

Post by Epsilon Delta »

The Wizard wrote:
ThatGuy wrote: 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.
It's mostly fear of the unknown, correct.
Nothing much to do with engineering science.
Everything to do with power: those who have it over those who don't...
Engineering includes a health dose of fear of the unknown. Engineers are conservative for a reason. When comparing "can't use an ipad for 8 hours" with "plane crashes" I know where I want to put the onus of proof.
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Re: Power Down in Airplanes

Post by Steelersfan »

The Wizard wrote: It's mostly fear of the unknown, correct.
Nothing much to do with engineering science.
Everything to do with power: those who have it over those who don't...
Probably so, but with a few hundred lives potentially at stake, that's not an experiment they want to conduct.

With every new RFI emitting electronic device that people might carry onto the plane.
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Re: Power Down in Airplanes

Post by Muchtolearn »

I often do not turn my blackberry off in the case not to be non-compliant but because I do not listen to anything those recorded announcements say. And I certainly ignore anything a flight attendant says. I tune out all announcements. If there was really a danger, all devices would have to be confiscated including those in the carry on bags under the seats.
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Re: Power Down in Airplanes

Post by masteraleph »

In addition to the reasons brought up so far, FAA regulations ban them unless "an airline [shows] a device does not interfere with safe operation of the aircraft during all phases of flight." http://www.faa.gov/news/fact_sheets/new ... ewsid=6275

Ultimately, airlines are not willing to go through the hassle of testing every plane configuration they operate with every device on the market. In theory, they could test only iPhones, and then permit iPhones but not Androids, but no airline will spend the time and money to do that. And even if they did, can you imagine the fights with the flight attendants by the owners of every other piece of technology?
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Re: Power Down in Airplanes

Post by Epsilon Delta »

masteraleph wrote: In theory, they could test only iPhones, and then permit iPhones but not Androids, but no airline will spend the time and money to do that.
In ThatGuy's report of Boeing's research you will notice that Boeing tried to test the particular suspect device. There's a reason for that. EMI can be very sensitive to details of construction. Exactly how a gasket or even paint is installed can affect whether or not a device meets it's emissions target. This means that somebody replacing a battery or cracked screen can make the device a worse source of interference than a similar device fresh from the factory.
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Re: Power Down in Airplanes

Post by XtremeSki2001 »

burgrat wrote:The flight attendants want your undivided attention.
This. Most people on planes just put their device in their pocket and never turn it off. If it was a problem, we'd have had an issue from it. The airlines should put more attention into keeping their planes well maintained (cough cough United/Continental).
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Re: Power Down in Airplanes

Post by Jerilynn »

XtremeSki2001 wrote: The airlines should put more attention into keeping their planes well maintained (cough cough United/Continental).
It's too expensive and cuts into profits. I think the bigger problem is pilot qualification, training and pay, however.

There was a Frontline episode a while back where they looked at the small regional carriers. It was kinda scary.

http://www.pbs.org/wgbh/pages/frontline ... heap/view/
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Re: Power Down in Airplanes

Post by THY4373 »

In a previous career I worked for a government agency and regularly flew on Air Force planes used by high level government officials. These were the planes used by Congress, Cabinet level officials and the like and were mostly commercial aircraft (Gulfstream and Boeing) converted for government use. Some were essentially commercial air craft with a U.S. Air Force paint job and others were fairly heavily modified. Anyway the Air Force let us run ANY electronic item at any time. The security folks and I (I did logistics) used Motorola Sabre radios on plane during take off and landing to transmit our arrival and departure. These things were many times more powerful than any commercial cell phone. In fact if you put one of the radios next to the 486 computers that were common at the time and hit the transmit button the computer would crash and require a reboot before it would work again. I am not an RF expert but clearly these things were pumping out a fair amount of RF and yet it did not impact those planes and their electronic equipment, not once. Folks used their cell phones to make calls as we approached landing. So I'd say it is mostly paranoia (perhaps healthy) that makes airlines do this.
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Re: Power Down in Airplanes

Post by XtremeSki2001 »

Jerilynn wrote:
XtremeSki2001 wrote: The airlines should put more attention into keeping their planes well maintained (cough cough United/Continental).
It's too expensive and cuts into profits. I think the bigger problem is pilot qualification, training and pay, however.

There was a Frontline episode a while back where they looked at the small regional carriers. It was kinda scary.

http://www.pbs.org/wgbh/pages/frontline ... heap/view/
I flew a small regional carrier, but operates via US Airways. We had problems all the time on the route I flew each week. One time during taking off there was a problem with the landing gear. We practically flew all the way to Philly and then turned around, put the wheels down (at 30k feet, mind you), put the flaps down, and started to ascend and descend. The pilot explained it was to burn off the fuel incase we crashed because of the landing gear issue. It ended up being fine and I slept over in the same city I just left only 4 hours prior, but landing amidst the plethora of medical and fire trucks sure was exciting!
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Re: Power Down in Airplanes

Post by nothlit »

I do put my devices in airplane mode to limit interference, but I never power them completely off. For many devices (e-readers, especially) there is very little difference between 'off' and 'standby' or 'sleep' modes, especially once the cellular/wifi/GPS radios have been disabled.
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Re: Power Down in Airplanes

Post by hicabob »

nothlit wrote:I do put my devices in airplane mode to limit interference, but I never power them completely off. For many devices (e-readers, especially) there is very little difference between 'off' and 'standby' or 'sleep' modes, especially once the cellular/wifi/GPS radios have been disabled.
They always bug me about my kindle (w/ 3g turned off) - the latest thing they have come up with to harass me about is my noise cancelling headphones (this insignificant source of rfi seemed to have become their latest hot-button about a year ago)
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Re: Power Down in Airplanes

Post by Epsilon Delta »

hicabob wrote: the latest thing they have come up with to harass me about is my noise cancelling headphones (this insignificant source of rfi seemed to have become their latest hot-button about a year ago)
Are you sure they're concerned about RFI from the headphones? I would think they would be more concerned that you couldn't hear. They want people to be able to hear instructions if there is a problem during takeoff or landing.
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Re: Power Down in Airplanes

Post by hicabob »

Epsilon Delta wrote:
hicabob wrote: the latest thing they have come up with to harass me about is my noise cancelling headphones (this insignificant source of rfi seemed to have become their latest hot-button about a year ago)
Are you sure they're concerned about RFI from the headphones? I would think they would be more concerned that you couldn't hear. They want people to be able to hear instructions if there is a problem during takeoff or landing.
Positive - turn off the NC so the little led goes off - turn up the volume to compensate for lack of no NC and they are all happy.
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Re: Power Down in Airplanes

Post by nitpar »

I was once told by an airline engineer that the real reason is too much back-n-forth “pinging” with multiple cell towers at the same time by too many cell phones.

Let me explain -
When all the passengers are on-land, all their respective cell-phones get connected with possibly 1 or 2 cell towers (whichever provided the strongest signal).
When all the passengers are airborne i.e. within say up to 1/2 mile in sky, all the cell-phones try to send-receive signals to multiple cell-towers (since a lot many cell-towers are now "in-range"). This means those cell-towers are unnecessarily getting “pinged” and wasting a huge amount of bandwidth (and money), which otherwise could have been used more productively.

By turning-off all cell-phones, the above gets minimized to a great extent. Did you even wonder why your cell-phone battery suddenly is significantly depleted (if you don't turn it off) after you land to your destination! Yeah, it’s the constant pinging against multiple cell-towers (while taking-off and then again at landing) that eats up a lot of the battery.

The instructions to turn-off all electronic devices are easier than just signaling out cell-phone so no one should feel more privileged (non cell-phone passengers).

Anyone believe this as a plausible reason?
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Re: Power Down in Airplanes

Post by Mudpuppy »

I think there are few plausible reasons or logical explanations. The regulations say electronic devices must be turned off during take-off and landing, and some airlines take a very hard-line approach to enforcing that regulation, such as the one going after hicabob's noise-canceling headset. It's just another headache of flying commercial airlines, along with exorbitant food prices and sales pitches for the airline's credit card.
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Re: Power Down in Airplanes

Post by Jerilynn »

nitpar wrote:I was once told by an airline engineer that the real reason is too much back-n-forth “pinging” with multiple cell towers at the same time by too many cell phones.

Let me explain -
When all the passengers are on-land, all their respective cell-phones get connected with possibly 1 or 2 cell towers (whichever provided the strongest signal).
When all the passengers are airborne i.e. within say up to 1/2 mile in sky, all the cell-phones try to send-receive signals to multiple cell-towers (since a lot many cell-towers are now "in-range"). This means those cell-towers are unnecessarily getting “pinged” and wasting a huge amount of bandwidth (and money), which otherwise could have been used more productively.

By turning-off all cell-phones, the above gets minimized to a great extent. Did you even wonder why your cell-phone battery suddenly is significantly depleted (if you don't turn it off) after you land to your destination! Yeah, it’s the constant pinging against multiple cell-towers (while taking-off and then again at landing) that eats up a lot of the battery.

The instructions to turn-off all electronic devices are easier than just signaling out cell-phone so no one should feel more privileged (non cell-phone passengers).

Anyone believe this as a plausible reason?
When I was flying, anytime I was above about 3000-4000 feet, I couldn't get a good cell signal because I was out of range. I had to use a sat phone at altitude. Now, if you are in the takeoff/landing phase I can see where the phone would ping multiple towers.
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Re: Power Down in Airplanes

Post by Polystallion »

Mythbusters... http://dsc.discovery.com/fansites/mythb ... ments.html
Finding: BUSTED

Explanation: Never mind what the chatterbox in the seat next to you says about cell phones messing with plane navigation -- those metallic birds are built airtight against foreign signals and operate on entirely different frequencies than cell phones.

So why all the fuss about phones? When you make a call at 10,000 feet, the signal bounces off multiple available cell towers, rather than one at a time. That means too many phone-happy jetsetters might clog up the networks on the ground, which is why the Federal Communications Commission (FCC) — not the Federal Aviation Association (FAA) — banned cell use on planes.

If you're just dying to bust out your BlackBerry mid-flight, go international. Some airlines in Europe, the Middle East and Asia now allow cell phone use in planes, but don't hold your breath for the FCC to follow suit.

As seen in "MythBusters: Cell Phones on Planes."
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Re: Power Down in Airplanes

Post by rdmayo21 »

I once heard a pilot say that cell phones not being allowed on planes is not because of interference, but because it would be a disturbance to others.
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Re: Power Down in Airplanes

Post by englishgirl »

Muchtolearn wrote:I often do not turn my blackberry off in the case not to be non-compliant but because I do not listen to anything those recorded announcements say. And I certainly ignore anything a flight attendant says. I tune out all announcements. If there was really a danger, all devices would have to be confiscated including those in the carry on bags under the seats.
Having had to evacuate a plane via the emergency chutes when an engine caught fire while taxiing, I now listen to every single one of those announcements. Including locating my nearest (and next nearest) emergency exit. The chute at my nearest exit malfunctioned, so a crowd of us had to go find different exits while smoke was coming into the cabin. A substantial percentage of the people around me froze in fear and didn't seem able to react once there was a real danger. It's amazing what a little bit of repetition/reinforcement from those messages does to the brain at the beginning of a flight.

Of course, this is off topic on electronic devices. I use the "airplane mode" on my iPhone. But it wouldn't surprise me if the air carriers and the phone manufacturers got together to turn all devices onto airplane mode automatically in the not-too-distant future.
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Re: Power Down in Airplanes

Post by MattinAustin »

I've got a Kindle "with advertising" and there is no way to turn it off. All I can do is put it in the seatback. I wouldn't mind it except on some flights they ask you to turn things off 10 minutes before landing and others its 30 minutes...a long time to read SkyMall.
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Re: Power Down in Airplanes

Post by garg33 »

Epsilon Delta wrote:
hicabob wrote: the latest thing they have come up with to harass me about is my noise cancelling headphones (this insignificant source of rfi seemed to have become their latest hot-button about a year ago)
Are you sure they're concerned about RFI from the headphones? I would think they would be more concerned that you couldn't hear. They want people to be able to hear instructions if there is a problem during takeoff or landing.
If that were the case, they'd also prohibit earplugs during takeoff and landing. Which they don't.

I normally wear earplugs on the plane, but I have found on the occasions where I have tried noise canceling headphones that I actually can hear the announcements better than without, since they do a much better job of blocking low frequency engine noise and the like than speech.
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Re: Power Down in Airplanes

Post by MachAF »

Sometimes the guys up front will hear interference with the radio communications (a clicking noise in the headset) if you leave your phone on. Usually it only happens with AT&T/ T-Mobile.
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Re: Power Down in Airplanes

Post by MachAF »

MattinAustin wrote:I've got a Kindle "with advertising" and there is no way to turn it off. All I can do is put it in the seatback. I wouldn't mind it except on some flights they ask you to turn things off 10 minutes before landing and others its 30 minutes...a long time to read SkyMall.
Whenever the plane goes below 10,000 ft electronic are required to be off. It all depends on what airport you're flying in and out of. Usually 10-15 minutes before landing. Sometimes its only 5.
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Re: Power Down in Airplanes

Post by abuss368 »

Leesbro63 wrote:What is the reason behind required electronics power down on commercial flights?
Hi Leesbro63,

I had heard it was so the very attractive flight attendants would have our undivided attention!

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Re: Power Down in Airplanes

Post by nisiprius »

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Re: Power Down in Airplanes

Post by gd »

Working as a flight instructor in small aircraft, I often could tell when a client had left a cell phone on in his/her bag in the back seat because of the intermittent mild interference heard on the aircraft radios. I doubt it happens on airliners, but the mythbuster "different frequencies" is nonsense, and any electrical engineer (me, for example) would snicker at the "airtight against foreign signals". It is also at best misleading about the regulations being FCC and not FAA. The airlines and pilots are responsible to determine safety of flight with respect to electronic devices:
http://ecfr.gpoaccess.gov/cgi/t/text/te ... &view=text
Given the swarm of lawsuits that descend on every incident or accident, there is no incentive to allow them. My position as a commercial pilot was that I always, always followed every conceivable regulation because 1) that's how you stay alive and 2) my clients could get hit by a meteor and if I had any record of errors, I'd be judged at fault by the quite clueless jury.

I'd rather not have my safety dependent on 1) an overworked, underpaid, harrassed flight attendant acting as electronics police, making judgements about acceptability 2) trusting consumer electronics companies to never, ever produce a future product that will not create RFI, and 3) the guy in the aisle seat next to me getting his laptop and cables and gadgets the hell out of my way when we skid off the runway.
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Re: Power Down in Airplanes

Post by nisiprius »

When smoking was permitted on airliners, did people complain about smoking being prohibited during takeoffs and landings?

One can imagine a smoker insisting that single cigarette can't ignite jet fuel; that the cabin is sealed off from the fuel tanks; that the ignition hazards from the engine itself are a gazillion times higher than from a cigarette; that pipes might be dangerous but a cigarette was not; demanding to know whether there was ever a case in which it had been proven that cigarette smoking during takeoff or landing had caused an accident....
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