Study: In-flight cell calls pose risk to planes

http://www.post-gazette.com/pg/06060/662669.stm

You might want to think twice the next time you're tempted to make a call from your cell phone during an airplane flight. Or flip on your portable game player. Or work a spreadsheet on your laptop.

Besides possibly annoying fellow travelers and breaking federal regulations, you might be endangering the airplane, according to a Carnegie Mellon University study that quietly monitored transmissions on board a number of flights in the Northeast.

The study, by CMU's Department of Engineering and Public Policy, found that the use of cell phones and other portable electronic devices can interfere with the normal operation of critical airline components, even more so than previously believed.

Researchers concluded that such devices can disrupt the operation of cockpit instruments, including the Global Positioning System receivers that are becoming more common in helping to ensure safe landings.

<snip>

And despite the ban on cell phone use during flights, the researchers discovered that on average one to four cell phone calls are made from every commercial flight in the northeast United States.

and have been providing documentation to back it up. I think if you try to use a cell phone from an airplane the steward/stewardess should take it from you. If you aren't a complete ass about it, they should give it back to you after the flight.

Same goes for games & computers & all other electronic devices that are on the airlines list (usually in a magazine provided by the airlines). They aren't just being random assholes. They actually do have a reason. If you check out the labelling on most computers & electronic devices, you can see that they emit signals that can cause interference. Are you really willing to kill everyone on that airplane because you just HAD to make that call before you land?

...or that call while you're doing 80mph on the turnpike. Either way, you're putting other people at risk due to your own behavior, which is about the height of selfishness.

a cell phone interfere with the GPS? They have a GPS is lots of cars and I've never heard anyone say your cell phone would cause problems with it.

there ar enumerous electronic instruments on board an airplane, and many of them are affected by random electronic radiation...

CD players and gameboys are relatively safe, and they're supposed to be turned off during takeoff and landing. Cell phones are not closed-loop systems and are actively broadcasting. They're dangerous all the time.

stating that they don't create more than a specific level of electronic interference. If you have electronic systems that are sensitive to that interference, wouldn't you rather that the generators were turned off (at least during take-off & landing)?

:shrug:

or confiscated if necessary...

there are people right here (in the 9-11 forum) that know for an absolute fact (and don't mind letting you know about it) that cell phones don't work in-flight.

This nonsense has been going on since cell phones first became common. As a pilot, and a computer engineer, I know a little bit about frequencies. And there is nothing about a cell phone transmission that causes problems for a GPS or other flight "instruments."

Notice that the article says "may" and is only very general about instruments being affected. GPS and cellular signals are much different. Many "instruments" on commerical airplanes are vacuum driven and use a "pitot static" system to identify alititude, climb rate, etc. The directional and attitude systems are gyroscopic.

No folks, this is about control and good old capitalism. They want to sell you phone service, and they want you paying attention to how to put on a seat belt instead of yacking on the phone.

If this were true, why haven't there been problems with the 100s of Blackberry's, Treo's, Pagers, and other devices that actually ARE the same as cell phones that never get turned off? Huh? It's because they can't compete with those.

Oh, did I mention who was the #1 partner with the US Dept of Defense for research and studies? Yep, Carnegie-Mellon.

Cell phones check with all the towers in sight, in order to find the closest one that itsn't too busy to take on a new call.

When you place a call while in the air you vastly increase the number of towers being "hit" by your signal. That can cause the cell network serious headaches.

That's what I've heard.

One plane load of cell phone users could shut down a regions cell towers.

Normally, a single cell phone can only contact 2 or 3 towers at once. But from a plane, it can reach hundreds. For each tower a cell phone can contact, there must be a calculation against all the other towers it can reach, in order to find its strongest signal at that moment. A few moments later it checks again, and again, and again.

Normally, with 3 towers in view, that involves 9 comparisons. If 10 towers are in view its 100 comparisons. With 100 towers in view its 10,000 comparisons.

Now, there are optimizing techniques which reduce that 10,000 result some, but the point is, a single cell phone from a plane causes problems. A lot of cell phones can shut things down.

The signal from the cell phone towers is directed out, not much goes up. The signal is low power and normally only goes a few miles, i.e., by design, far enough to over lap the adjacent towers signal. Above 10,000 feet or so cell phones do not work, period. There are no signals for the cell phone to detect. That signal strength indicator bar you see is random noise as the cell phone is scanning when trying to find a signal.

Also keep in mind commercial airplanes are metal. You are inside a shielded enclosure. Just because it works at the terminal does not mean it will work at the end of the runway and beyond. Holding you phone close to the window will only allow signals in from that direction. And even then any signal is greatly attenuated by all that metal.

So may experts, so little education.

always cruises much higher than that and my passengers make cell phone calls all the time with no problem. And none of them have ever interfered with the instruments.

Let's take just one alleged "fact":

Cellphone signals can't propagate through airplane
windows except maybe as a narrow beam (paraphrasing
what he said)

Radio waves have a certain "size" (wavelength) that depends
on their frequency. Generally speaking, they can't fit through
an opening in metal if the opening is less than about 1/4
of the wavelength.

The original cell phone system used radio at about 850 MHz.
That makes the wavelength of the radio waves about 14 inches.
1/4 of that is 3.5 inches. Last time I looked, airplane
windows were a bit bigger than 3.5 inches in all dimensions
(height, width, and diagonal distance).

Newer cell phone systems operate at about twice the frequency
and therefore, a wavelength that's about half as big, say
1.75 inches. There's absolutely no problem passing this
wave through an airplane window nad having it radiate in
at least a full hemisphere.

Tesha

that can be affected by computer systems and the electronic interference that they create? Or are you speaking solely to cell phones?

I've never had the steward/stewardess ask that I put my book away & pay attention to their presentation, so the comment about paying attention to their presentation on putting on your seatbelt seems a bit specious...

The problem, and the article, was not about computer systems - but cell phones. I assume you read it before commenting. What do "computers" and other small electronic devices transmit? No airline systems use Bluetooth, nor do they use 802.11 Network, or modem signal - if such a thing were even feasable

As far as attention, I have 1.5 million miles on NW Airlines and can tell you that I, for one, have been asked to pay attention quite a few times.

other portable electronics and laptop computersas well as cell phones.



It says that the FAA hasn't found these devices to interfere, but the airlines have been claiming that they do interfere, but not enough to cause problems except at take-offs and landings.

I'm not referrig to the use or wireless networking protocols, though. I'm referring to the FCC class B device labels that have been on computers for most of the last 25 years (probably longer, but I've only been working on computers that long). They indicate that the computer creates interference that is at or below certain levels of intensity. Depending on where in the aircraft that interference is being created, I can see how it may cause problems.

However, the fact that many laptops & other devices now have antennas in them that are intended to create electronic signals in a very narrow band doesn't prevent them from causing harmonic interference in other bands (that's why HAMs sometimes have to install chokes on their neighbor's TV antennas - to prevent the harmonic interference, even though the TV operates in a different band).

I don't have the mileage that you do in aircraft, but I've been flying for many years, always read during the vast majority of time I'm on-board, and have never been asked to "pay attention." As far as I can tell, it's quite likely that I never will unless I were interfering with someone else who wanted to listen.

I can tell you that I don't fly on Northwest unless they're the only ones going to my destination because I abhor their practices. I've had reserved seats taken away when traveling with MY family because someone else wanted to sit with THEIR family. It was the last straw and I will drive/walk/swim before I fly Northwest again. Maybe you got that because you were on a Northwest flight.

> So there aren't any systems in an airplane that can be
> affected by computer systems and the electronic interference
> that they create? Or are you speaking solely to cell phones?

Computers and all other modern digital electronic
devices (basically all the gadgets we carry fancier
than a cassette-based Walkman) spew out electronic
noise at a wide variety of frequencies and the
frequencies aren't entirely predictable, although
a very popular set is *EVERY HARMONIC* of 33 MHz.

While I don't think it's *LIKELY*, it is entirely within
the realm of the *POSSIBLE* that a given set of passengers
might power up a particular collection of devices that
cause interference with the electronic systems of the
plane.

Someone earlier questioned how GPS could be affected
by cellphones. GPS operates at a frequency that is
just below the second harmonic of the frequencies
used by early cell phone systems. It's quite possible
that a malfunctioning cell phone could have "spurs"
(spurious noise outputs) that fall into the GPS
frequency band.

Tesha

You can't get away on an airplane. I sure don't want to hear about another person's problems.

The idea of being stuck on an airplane with a load of self-absorbed "my life is SOOO important that everyone should know about it" twits is horrifying.

have to listen to folks announce their position on the tarmac . . . "Honey, we're taxing now." "OK, we just landed." Who gives a #@%$? How did the world survive before cell phones?

but the techno-junkies have convinced everyone that the darn things are "necessary." If you disagree you're a techno-phobe, a luddite, or just to stupid to "get it."

I get it -- I just don't want it.

from the 9/11 flights?

The official 9/11 story has more holes than a worn out sieve.

The FAA and the FCC both have something to say about this. This article is about the aviation side, and hence the focus on an FAA study. But even if the FAA said that cell phones were fine in airplanes, they still counldn't be used, because the FCC regulates radio devices.

As far as the FCC is concerned you can't even use cell phones from a hot air balloon. It has nothing to do with aircraft safety, and everything to do with the fact that the cell phone system simply wasn't designed to handle airborne operation.

Section 22.925 Prohibition on airborne operation of cellular
telephones installed in or carried aboard airplanes, balloons or any
other type of aircraft must not be operated while such aircraft are
airborne (not touching the ground).

If cell phones work at altitude then why are airlines STILL discussing methods to make them do so? And if they do not-why do we have dozens of cell phone calls making it on 9-11??? Both CANNOT be true but both have been reported on DU...I have seen posts stating that cell phone contact is impossible at over 9000' and posts stating that flight 93 passengers made dozens of calls while above that altitude...including passengers calling,connecting,disconnecting and then reconnecting at will...someone is lying-who do you suppose that is????

i HATE people yammering on cellphones. you're stuck next to the person next to you for hours, only inches away from their mouth, and pressed up against them. imagine being trapped between two people yammering away for 3 hours... I'D KILL MYSELF FIRST.

imagine being stuck next to some asshole who WILL NOT SHUT UP. Now I can tune them out. I hate to see the day they ban electronic devices (other than cell phones). That is the day I stop flying because the flying public are assholes who make too much fucking noise.

It had no links with terrorism, just as Flight AA587 or Flight TWA800 had no links to terrorism. No, no links with terrorism at all. Just move along, no story. Your government is protecting you, no need to worry. :sarcasm: