Study: In-flight Cell Calls Pose Risk To Planes

Pittsburgh Post-Gazette ^ | March 1, 2006

[Wolfie]

Study: In-flight cell calls pose risk to planes

CMU group finds danger increasing

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.

[TommyDale]

I would be curious about how much influence Verizon had on this study. The study found their in-flight telephones harmless, but all other electronic devices were suspect. I don't know anyone who actually uses the AirPhones at those ridiculous prices.

[jdm]

"Study: In-flight Cell Ccalls Pose Risk To Planes"

That's what you get for copying and pasting the title, then trying to capitalize the first letter of each word, on your own. LOL. [ Just teasing. Happens to me too. ]

[UB355]

Difference being external antenna

[Hunble]

Isn't it amazing how cell phones never interfere with GPS receivers while driving a car?

Something is very fishy about this report.

[American_Centurion]

Yeah, whatever.....

Puhlease, if aircraft electronics are that freakin poorly designed, they should be falling out of the sky everytime they pass over a cell tower, powerline, radio/tv station, or police car.

CMU, can go blow that smoke up someone else's $^%!

[El Gato]

Somehow I still think that using your cell phone in flight, during the cruise phase, is less hazardous than that Jihadi in first class. :)

Flight 93 would have impacted the Capital building, if not for the cell phones of the passengers being used to find out that the country was under attack, and that what was happening to them was no ordinary hijacking, were the plane flies to Cuba, Libya or Lebanon.

[NonValueAdded]

Now that you mention it, I'm surprised that TSA doesn't confiscate cell phones in keeping with their policy to have the passengers as defenseless as possible.

[George from New England]

I notice that Southwest Airlines has no issues and allows passengers to use GPS devices IN FLIGHT. Very cool to be able to track your position, see altitiude and look at ground features.

No problem.

But Delta and AA bans GPS devices and will get you on a no-fly list if they catch you.

[TommyDale]

True, but that's not the point. I think the study has been corrupted by Verizon.

[grobdriver]

Hmmm... GPS frequencies: Military 1227.6 MHz, Civilian L1: 1575.42 MHz Civilian L2: 1227.6 MHz

Cell phone frequencies: 800-900 MHZ.

Yep - I can see interference out the wazoo...

[El Gato]

Puhlease, if aircraft electronics are that freakin poorly designed, they should be falling out of the sky everytime they pass over a cell tower, powerline, radio/tv station, or police car

It's not that simple. The cell phones and other RF devices are much, much closer to the equipment and antennas than any of the things you list. While the mobile devices generally are lower power than fixed installations, they also generally are not as well shielded as to their internal emissions, nor are their antennas as well isolated from those internal sources. These days the clock on your computer is running at a frequency in the low microwave region, and due to the shape of the waveform, has lots of higher harmonics as well.

It's not a question of the susceptibility of the aircraft electronics, but rather of out of band, or unintentional, emissions of the consumer equipment.

That said, GPS is pretty impervious to most kinds of interference, due to the nature of the signals it uses.

[Wombat101]

No there isn't anything fishy about it.

As a former computer operator and system's programmer, it has been common knowledge that radio emissions from CRT's routinely affect other components in a data center. In one example that I can personally vouch for, I know that stray radio signals from these tubes actually set off the alarms on a nearby electrical panel (I cannot, hwoever, describe the machanism, but it had something to do with radio freqeuncies interfering with the flow of information from the panel to the central control system, a wireless system).

In another example, three years ago when I was placed in a Cardiac Telemetry Ward in a local hospital (all the patients were hooked up to portable EKG units, about the size of a steno pad, taped to their chests), the use of cell phones, PDA's and blackberries was strictly forbidden.

I also can recall (dimly) that the brouhaha over stray electronic signals started way back with the first Airbus jumbo jets and the sensitivity of the "fly-by-wire" system.

None of this is new.

However, I believe the best result to be achieved from these kinds of studies is to shut up rude and inconsiderate people who use their cellphones loudly and abundantly. Nothing like taking a trans-Atlantic flight sitting next to an idiot who believes his conversation can't be heard when he's shouting over the normal cabin noise. Few things are as annoying as trying to sleep or otherwise relax on a long trip only toi be interrupted by several ringtones running the gamut from Beethoven's Fifth to something resembling a Klaxon Horn sounding General Quarters.

[longtermmemmory]

Business people working on time critical projects.

This study is suspect.

Why don't we have automobiles failing with thier computers, boats don't have GPS failures.

[George from New England]

"if aircraft electronics are that freakin poorly designed, they should be falling out of the sky everytime they pass over a cell tower, powerline, radio/tv station, or police car."

You're so right...the RF field from a 5 million watt TV tower within one mile is so much stronger than the little sub-one watt signal from a cell phone.

Follow the $$$

[BritExPatInFla]

Puhlease, if aircraft electronics are that freakin poorly designed, they should be falling out of the sky everytime they pass over a cell tower, powerline, radio/tv station, or police car.

The study seems to bear out what we've thought all along. Clee phones would be dangerous to only one system on an aircraft....The 3.00 per minute airphones in the seatback in front of you.

[A.A. Cunningham]

How many CAT IIIc approaches have you flown in your car while using your cellphone?

[TommyDale]

My guess is that Verizon has recently made a big donation to Carnegie-Mellon.

[goldstategop]

You are instructed not to turn on a cell phone during flight. In practice, they let people work on their laptops once the plane's airborne.

(Denny Crane: "I Don't Want To Socialize With A Pinko Liberal Democrat Commie. Say What You Like About Republicans. We Stick To Our Convictions. Even When We Know We're Dead Wrong.")

[Textide]

I've accidentally left my cell phone on while on training flights before in light aircraft. When it searches for a signal or you get a phone call there's audible interference. Never noticed if the instruments indicated any differently though. Suppose it's possible that a strong signal could throw off the instruments.

My instructor has a cell phone adaptor for his headset and regularly takes calls during non-essential flights/portions of flights (i.e. not using radio navigation for approaches or while on an IFR flight).

[TalonDJ]

Puhlease, if aircraft electronics are that freakin poorly designed, they should be falling out of the sky everytime they pass over a cell tower, powerline, radio/tv station, or police car.

They are not poorly designed and this is a real risk. I don't have the time to explain the design issues and constraints fully since I am freeping at work (for a major avionics company).

[ARCADIA]

Study: In-flight cell calls pose risk to planes

Possible Translation: They wouldn't want you to call mommy, FOX, or CNN when that nice F15 puts a rocket into your airliner.

[TalonDJ]

You're so right...the RF field from a 5 million watt TV tower within one mile is so much stronger than the little sub-one watt signal from a cell phone.

1: they are on very difference frequencies
2: The tower is OUTSIDE the skin of the aircraft. That skin shields the avionics systems from most RF issues.
3: The cell phone is on the INSIDE. Which makes the issue worse as the signal reflects around the inside of the skin of the aircraft.
4: Cell frequency ranges are more problematic ones than TV or Radio.

[TalonDJ]

GPS in a car is not use to land the car on the road while traveling very fast, in a fog.

[paradoxical]

IIRC ATT wireless has a tri-mode phone that also has 1900MHZ..I could be wrong, have been before, maybe one of our tech freepers could verify,

But,yes I could see a company skewing data to monopolize.

[TalonDJ]

That is because they ban anything receiving RF. A receiver has a oscillator and an antenna and can cause some level of interference. Yeah, it is ridiculously low, but hey, that is FAA regulations for ya.

[doc30]

I notice that Southwest Airlines has no issues and allows passengers to use GPS devices IN FLIGHT. Very cool to be able to track your position, see altitiude and look at ground features.

I think the other airlines banned their in flight use because the 9/11 hijackers used such handheld devices to navigate the hijacked planes to their targets.

[American_Centurion]

4: Cell frequency ranges are more problematic ones than TV or Radio

I don't doubt that they are, but I have to question why they are. My guess tells me that it is because (at least partially) the design of the aircraft equipment has allowed it to be problemattic. Because, you know, passengers can always use the Airphone®.

[Blueflag]

Oh yeah!?!?!?! Well, they are, um CLASS B, yeah that's it, and, and, and they LEAK really bad in all those other frequencies!! And, um, all the electrical motors on the plane are fully shielded, and they don't create any interference or impedance.

< / sarcasm off >

Personally , I just don't want to have to deal with the inconsiderate oaf three seats over talking (over the wind noise) on his cell phone and inviting ALL of us to enjoy his side of the phone call.

[TalonDJ]

Exactly. Most people don't realize that RF interference causes issues in ALL sectors. They just thing airlines are being nutty when they ban such things. After all, how can planes be so fragile? And then they don't think twice when their cell phone randomly drops a call do to interference. They just shrug and dial again. Except in planes it is to risky to have your avionics reboot in flight. Or your radio scramble a weather report. Or key sensors be automatically ignored because the data is corrupted but a cell phone call putting noise on the signal lines running from the sensor up tot he cockpit...
The articles says there have not been ACCIDENTS. But there HAVE been INCIDENTS where use of electronic devices in the cabin has caused problems, little things like the plane suddenly turning left for no reason, stuff like that. They just did not crash any plane so most people don't know they ever happened.

[TalonDJ]

The air phone uses an external antenna and transmits on a frequency carefully chosen to not interfere. Cell phone frequencies were chose based on, what bandwidth was left over after years of FCC allocations, and what RF circuits could be build in a small package. Use in side aircraft was not considered when the freqs were picked.

[AUsome Joy]

The last few flights I have taken didn't have phones on the backs of seats. I have been on about 4 different airlines. Do some airlines still have them?

[Blueflag]

Red herring there mister cunningham. ;-)

How many CAT IIIc approaches have EVER been disrupted by electrical interference known to be emanating from Class B/ Cell/WiFi/etc passenger devices on the aircraft????

The aircraft can be struck by lightning on final, fly over 100,000 volt distribution lines, fly by a 50,000 Watt AM tower -- and still complete a CAT IIIc approach.

I remain skeptical

[ndt]

"Very cool to be able to track your position, see altitiude and look at ground features. "

A recent flight I was on had that built into the back seat (along with a dozen tv shows and movies to pick from). It really is a very cool thing to be able to tell exactly where you are flying over. I spent almost the entire flight just staring at the little red airplane. I'm easily amused I guess.

[N. Theknow]

What kind of avionics do these planes have?

In my industry we have to have mission critical instruments for measuring and controlling temperatures and other parameters that are impervious to electrical interference.

[TalonDJ]

PCS phones are in the 1850 range. Interference is not limited to the primary frequency of an RF device. GPS signals are very low strength.

[Revolting cat!]

A study conducted by the cat has concluded that cell phones interfere with human intelligence.

But, as with the Internet, cell phone help us find out quicker who the idiots are.

[TalonDJ]

The aircraft can be struck by lightning on final, fly over 100,000 volt distribution lines, fly by a 50,000 Watt AM tower -- and still complete a CAT IIIc approach.

Maybe but maybe not. The autopilot will disconnect if a sensor goes down or is rejected for having bad data. A transmission source inside the pressure vessel is much more likely to corrupt data than a much larger source outside that shielding that the aircraft structure provides.

[American_Centurion]

And to this date it is of financial interest to airlines and Airphone® to make sure that current and future aircraft systems are, at least insignificantly, interferred with by cell phone freqs from within the aircraft.

It's absolute BS that for at least the last 10 years aircraft systems are still unable to cope with the weak cell phone signal. There is without a doubt financial incentive to make sure it is a problem that never goes away.

[sono]

My gut feeling is that this is bogus ... They used to say the same about wireless calls and hospital intrumentation until the accumulated evidence revealed This.

[Wombat101]

Here's something to think about:

Most data centers have shielded walls (often steel, often 1 inch, or more, thick) to specifically block out stray RF frequencies which can interfere with the transmission, storage and transfer of electronic data (which is all done electromagnetically. Radio signals are part of the elctromagnetic spectrum).

Likewise, older analog equipment is typically connected with teflon-shielded copper cable. The teflon is required a) to prevent the cable from fraying and breaking, b) to insulate against fire and c) to prevent radio signals from interfering with the flow of data along the cable (the newer fiber-optic cables in use eliminate most of these problems).

Just to prove that stray RF signals can possibly present a threat to an aircraft, ask yourself: how many times have you picked up your wireless phone in the house, and gotten a load of static, or worse, caught a snippet of someone else's conversation? Now that's a system (wireless telephone)designed to operate in a certain area of the EM spectrum. Occasionally, due to atmospherics and other factors, the phone actually picks up other signals outside it's frequency range (both in terms of actual EM bandwith and geographic distance).

Imagine what would happen to a flight control system at a critical time if it began to pick up stray signals due to the same considerations? How'd you like it if the pilot couldn't deploy flaps on landing because the person sitting next to you couldn't wait ten minutes to call his ride waiting at the terminal?

[TalonDJ]

So do we. We have all kinds of EMI requirements to meet. They are handed down from the FAA and based on certain things. Most things they just shrug off. The levels of EMI resistance that avionics have to meet for in flight operations are not based on having cell phones in use aboard. They could be designed to do that... but currently they are not.

[dalereed]

Total BS, aircraft systems and com equipment operate on totally different frequencies.

The origional notice to pilots didn't come from the FAA, it came from the FCC!

When a cell phone is used from an aircraft it disrupts the cell communications because it has direct line of sight to a lot of cell towers that all fight to take the signal.

[Old Professer]

I used to work at the U.S. Navy Postgraduate School, 1966-70 when weather satellites were new and mysterious; as we were a teaching installation, it was decided that we should be able to plot and track the satellites, TIROS and NIMBUS series, copy the printouts and use them as instructional aids.

A receiver was installed in our laboratory connected to a tracking antenna on the roof of an adjacent building which gave us a horizon to horizon sweep by manually fine-tuning the signal strength.

Each satellite had its own precession rate and the morning of the pass we would warm up the radio, turn on the on-loan Wollensack portable reel to reel recorder and preset the antenna to the proper location along the near horizon.

While warming up the radio we would maximize gain and wait for the first beep.

One morning, we turned on the set and, to our great surprise and consternation, found ourselves listening to a San Jose FM radio station

A few frantic calls through information finally got us through to the station engineer who, at first, refused to believe us and would only check out our complaint after we patched him through to the highest ranking Navy officer available.

The problem was cleared up about five minutes before the satellite came within range.

BTW, when the copied printouts from our station (we kept everything) were compared to the multi-million dollar La Jolla facility ours were requested by the top brass for archive use.

I was a research assistant to two of the professors there at the time. A lot of good work goes on behind the scenes.

[Blueflag]

Understood. ... to a point. So, how well shielded will the new composite aircraft be? eh? No all encompassing Al skin and frame ...

I find it REALLY hard to believe that a 3 watt (or less) signal source can generate enough out-of-band interference to disrupt digital telemetry of avionics. Are their signal-to-noise ratios so poor that they can't handle leaks from a laptop or cell phone?

I like to deal in facts. WHEN, if ever, have you read an article that purported to report that cell phones (and similar) actually disrupted ANY flight operation? [except when a fight in the cabin broke out over their use ;-) ] I don't read Flying and Air&Space as much as I used to, but I can't recall ANY article, ever.

I am ready, however, to leave my ignorance behind and join you (and others) in believing the threat on-board low power civilian transmitters present. Seriously ;-)

[ml/nj]

It's not that simple. The cell phones and other RF devices are much, much closer to the equipment and antennas than any of the things you list.

Yeah. But the antennas are on the outside of the plane, and whatever mini-RF generators there are are inside, inside a big Faraday cage.

ML/NJ

[N. Theknow]

They could be designed to do that... but currently they are not.

What rationale is behind this?

The plane is at the mercy of a shoe salesman from Keokuk bragging about a big order or a teeny-bopper with raging hormones that just has to talk to that special someone?

[American_Centurion]

What rationale is behind this?

$$$$$$$$$$$ CHA CHING!!

[TalonDJ]

Not only that but there are hundreds, sometimes thousands of wires running down the length of the plane. All of them are stuck inside the skin with what ever phone calls people want to make bouncing around inside there with them.
Yeah fiber-optics are coming to avionics but not very fast.