ABC News documentary - are cell phones dangerous in flight - myth or fact?

[Julian Hensey]

An aviation safety database maintained by NASA shows a handful of incidents each year reported by pilots who suspected cell phones and other electronic devices had caused a problem during flight. Despite these reports, not a single air crash has been proven to be caused by the use of a cell phone onboard a plane.


John Nance, an ABC News consultant and veteran airline pilot, says there's little reason to worry about cell phones interfering with an airplane's navigational equipment. He says an airplane's electronic systems are "all heavily shielded. That means that stray signals cannot get into those systems."


But don't break out those cell phones just yet. The airlines can't allow cell phones to be used in flight until the technology has been proven safe. However, according to Nance, the Federal Communications Commission and the Federal Aviation Administration "have not done their job over about a 25-year period. And the airlines have quite properly said … if you're not going to tell us, then we're just going to default to the most conservative position and say we're not going to use them in the air."


"The evidence strongly supports that there is a risk," said Bill Strauss, an electromagnetic interference expert.

According to Strauss, cell phones emit strong radio signals that could cause false readouts on an airplane's navigational equipment. Strauss and other researchers from Carnegie Mellon University invented a device that detects radio emissions from cell phones and other electronic devices. They tested 37 commercial flights and learned that on each flight between one to four cell phone calls were placed. But do those rule-breaking cell phones really affect the plane's equipment?


The FAA told ABC News it has been collecting more data; the FCC said safety is the FAA's responsibility. Though the agencies may not be ready to allow cell phones on airplanes here, the rules have already changed in Europe.



The European Aviation Safety Agency has approved a technology that reduces the risk of interference with airplane electronics. Several European airlines will allow passengers to use cell phones in their skies, as well as wireless Internet, starting in 2008. Airlines in the United States will begin using a similar technology next year, but because cell phone use is still banned, the service can be used only for wireless Internet access.


http://abcnews.go.com/2020/story?id=3964895&page=1

[Avman]

To be honest, this subject has been done to death. As far as I'm concerned, even if it's perfectly safe with regard to the aircraft's operation, to avoid me committing murder I want to see the use of cell phones on aircraft banned for life (well, during my life anyway)!

[soddim]

There are also possible issues with fly-by-wire control systems.

[CityofFlight]

I'm with Avman...

Last thing I have patience for is sitting in a confined space for hours while listening to simultaneous conversations being yelled into cell phones. :ugh:

As far as I'm concerned, let sleeping dogs lie.

[Intruder]

Despite these reports, not a single air crash has been proven to be caused by the use of a cell phone onboard a plane.
John Nance, an ABC News consultant and veteran airline pilot, says there's little reason to worry about cell phones interfering with an airplane's navigational equipment. He says an airplane's electronic systems are "all heavily shielded. That means that stray signals cannot get into those systems."
So, we FIRST have to have a crash "proven" to be caused by a cell phone before we should ban their airborne use? I don't think so... Maybe it merely shows that the present policy has adequately protected us from such crashes!

Maybe John Nance's experience in MD-80s and/or 737s qualifies him to talk about those, but there have been several verified reports of EMI problems aboard other airplanes due to cell phone use. The WiFi problem reported by 214 above is new to me, but it adequately demonstrates how such EMI could CAUSE a crash due to erroneous RA triggers!

[Agaricus bisporus]

No proof exists that locked flight deck doors will save lives, yet we are legally required to use them.

No proof exists that smoking in the vicinity of an (AVTUR fuelled) aircraft is in any way hazardous, yet it is strictly banned.



Sometimes there is no conclusive evidence to justify things, sometimes there is...This is one case that is quite clear, thank you.



There is ample proof that allowing languages other than English on the RT is a real threat to life (and bodies to prove it too, but sadly not a big enough pile of them, so far...), yet it is allowed, and in some places, notably the site of one of those bodies, fanatically supported.

There is no evidence whatever that aircraft are in any way designed to be immune from on-board electronic interference - A380 possibly excepted. (Statements like are all heavily shielded. is factual bunkum. Even it it were true on a modern Airbus (which it isn't) what about a 737-300 or a MD83 - designed before cellphones existed? Nonsense!

Come on, people, open your ears to what your mouths are saying!!!

And,

there is ample evidence that we just don't understand the complexities of electromagnetic propagation patterns from randomly placed transmitters inside complex metallic structures.

Its a complete no-brainer, isn't it? The answer can only be NO NO NO.

[ChristiaanJ]

WiFi interfering with TCAS... sounds scary enough to me.....

Intruder,
It would not just need a crash; it would need a crash proven to have been caused by EMI from "something" in the cabin.
Try and extract that sort of information from a smoldering wreck?

I tend to scoff at all the "principle of precaution" waffle these days.
But in this case, I'm all for it.

soddim,There are also possible issues with fly-by-wire control systems.Most if not all of that does pass through shielded wiring. The main problem is with aircraft systems that emit and receive RF signals on frequencies similar to that emitted by the typical electronic devices that we carry around with us, such as cellphones, video games, laptops with WiFi, etc.

[soddim]

ChristiaanJ, the point you need to look at is whether the relevant EMC trials have been done on each type of aircraft you think mobile phones could be used on.
If the trials have not been done then their use could be unsafe.

[airsupport]

While there is NO way I would want to be seated with hundreds of other passengers all chatting away on their mobiles :eek:, I really do NOT believe there is any danger in using them, apart from the danger of maybe strangling a fellow passenger.

I have spent many many hours, although not on FBW Aircraft, where sometimes all 3 people in the Cockpit have been using mobile phones during cruise, and we never had any problems.

There was even a Company owned mobile phone FITTED to the Cockpit rear wall, just had the ringer disabled at low altitude so as not to be a distraction on take off or landing.

[matt_hooks]

Well, I can definitely say, without a shadow of a doubt, that a mobile phone left switched on CAN have an effect on navigational equipment, namely the NDB. This is in a light piston twin, but it proves that they can cause emissions in a wave band that might interfere with navigational equipment.

On an instrument training flight, I noticed that the NDB reading seemed to be unreliable. I would normally have suspected some kind of electrical storm activity, except that the conditions outside the screens were CAVOK with no storm activity forecast or reported.

I noticed that the interference was transitory, but was causing a swing to the exact same point on the dial (towards the rear of the aircraft), no matter what direction the aircraft was doing. This told me the interference was on-board the aircraft.

This was the only indication of a problem, no other instruments were showing spurios or unexpected readings of any kind so I continued the flight and carried out an ILS with the screens down for safety. This was perfectly safe due to the good VMC.

On taxying in we investigated the aircraft, and found that a mobile phone had been dropped behind the rear seats, and the owners attempts to find it by ringing it had been the cause of the interference.

So can mobiles interfere with the equipment, undoubtedly. Is this likely to be a risk?

Well, imagine a descent into a field way out in the middle of nowhere, the only approach is an NDB approach, and you have obstructions on either side of the approach track. You are flying at minima, so no visual clues, and the NDB needle is dancing around. Are you likely to trust the NDB? At the very least you're likely to get a go around and probably a diversion!

[Roundtail Jimbo]

Actually, I don't believe cell phones pose a risk to flight safety due to electromagnetic interference. I've spoken with many experts in radiofrequency who tell me that the signal strength is just not strong enough to affect shielded avionics. I personally have never experienced any incidents of interference. Also, apparently Boeing did quite a few tests to try to reproduce problems reported by flight crews and weren't able to reproduce anything:

http://www.boeing.com/commercial/aeromagazine/aero_10/interfere_textonly.html

However, I still believe in a total ban on cell phones in flight. I believe they pose a serious danger to flight safety for the following reason. If you have hundreds of passengers talking on cell phones, screaming above the engine noise, it will create an enormously stressful environment for the cabin crew and passengers. This will significantly increase the risk of incidents of violence. Also, cabin crew and passengers will be much less effective in responding to any emergency, such as an evacuation, in such an environment.

So, I say let's keep the ban...

[SLFguy]

Oh God...not again....purleeeze!

[PBL]

For once, almost unanimity!

I disagree with Avman: the topic has not been done to death. Indeed, from a scientific or engineering standpoint it has barely begun, even after a couple of decades. There are good reasons for this, some of which I mention below.

Nance's quoted remarks appear to be trivial and uninformed. If he really said that an airplane's electronic systems
all heavily shielded. That means that stray signals cannot get into those systems.
then he is *obviously wrong*.

Whether avionics can be affected by internal EM fields depends, most obviously, on the strength of the field: if I started up a tomography machine in the cockpit I can guarantee you that some things will go haywire.

The pertinent question for airline ops is whether avionics can be affected by field strengths of the order of those generated by portable electronic devices. What is known is
basically this: (1) that measured field strengths turn out sometimes to be greater than previously assumed, and (2) all the modelling codes have exhibited "spikes" at particular positions whose strength is orders of magnitude above the average field strength.

The newspaper may have been selectively quoting, but I hope Nance knows about the engineering work and will correct his statement.

I think there are two major pieces of work that anyone interested in this topic should know about.

One is the set of tests performed by the U.K. CAA some years ago, in which they measured the field strength of cell phone transmissions in various parts of an airplane, and found that in the cockpit area at least the field strength in some locations was stronger than previously supposed. The report is on the CAA WWW site.

The other is the extensive modelling work performed by NASA during the course of the TWA 800 investigation. A Harvard English professor, Elaine Scarry, proposed in a literary-political publication, the New York Review of Books, that EMI could have brought down TWA 800. The NTSB Chairman at the time entered into public correspondence about it. Result was a research contract to NASA to look at it. There are a few pages of the report devoted to the Scarry scenario, in which EMI came from outside the aircraft, and the bulk of it is devoted to the attempt to model fields generated *inside* the cabin. It is quite long, and you need to be an experienced numerical analyst to be able to glean useful information from it. It is in the TWA 800 docket, if this is still available on the WWW.

I worked with an electrical engineer, Willie Schepper, who assessed the possible effects upon experiments in the Department of Physics of extending tram service to the university here (the trams now run some 200m away from the building, rather than under it as first envisaged). He said that all the codes used for estimating field strengths in enclosed spaces are hand-me-down from the U.S. military, and obviously places like NASA get their hands on them first (partly because they are already used there when they are declassified). We advised the TSB on the SW111 investigation.

It is not trivial to perform assessments of the effects of fields in enclosed spaces, and claims to know with quasi-certainty (as the newspaper presents Nance) about certain effects should be treated with a dose of healthy scepticism.

Electric/electronic control systems, as ChristiaanJ says, are far more effectively shielded than nav gear or advisory systems such as TCAS which depend upon external signals. To my knowledge (although I can no longer claim to be up to date) there has not been one report of control systems apparently being adversely influenced by passenger electronics, whereas there have been thousands of such believable reports about nav gear coming from professionals who did their best to diagnose the problems in the air. The problem with verifying such reports is twofold: what happens in the air is different from what happens on the ground when the airline maintenance people try to test (different air pressure means different phenomena!); and the passenger whose untested electronic device may have been generating interference is usually unwilling to let his kit hang around the airport for a few days so that the airline can play with it. Neither of those two issues is ever going to go away. So one can continue to expect far more reports than can be definitively verified; it does not mean the phenomena were not present.

I heartily thank TwoOneFour for the TCAS interference report. I haven't been keeping up, but that is the first report about interference with a non-navcoms system I have read. (Or do we count TCAS as navcoms?)

PBL

[deplanedeplane]

No, no, no ,no, no, and once more for the idiots NO!.

Travelling is difficult enough as it is now, lets not find ways to make it worse.

[aeroDellboy]

As a regular passenger, I DON'T want phones, it's the only place I get away from them at the moment!

My company also carry out EMC testing on machinery, and we see numerous occasions where manufacturers have followed guidelines and codes, and still there are problems. Not so much of a problem in a factory on the ground, but at 30,000 feet it is a different matter.

I believe the reason the latest trains were delayed for so long into the UK was that EM interference from the electrical systems was interfering with the signals. From memory, the delay was about 18 months while they tried to get it right by testing all possible configurations. Can't see that is possible to do that level of testing on every model of aircraft.

[Avman]

PBL, just do a search and you will see that the topic HAS been done to death on PPRuNe. Looking at all your posts lately, I think that you just have too much time to spare. ;)

[bookworm]

One is the set of tests performed by the U.K. CAA some years ago, in which they measured the field strength of cell phone transmissions in various parts of an airplane, and found that in the cockpit area at least the field strength in some locations was stronger than previously supposed. The report is on the CAA WWW site.

Unfortunately it's not but it does appear to be here:

Interference Levels In Aircraft at
Radio Frequencies used by Portable Telephones (http://gpsinformation.net/airgps/gsm_intf1.pdf)

They tested various powers, frequencies and aircraft and concluded that a 2W transmission (maximum a phone radiates) from the forward cabin in a 737-236 could produce a 4.5 V/m field in the flight deck. The highest seen in the avionics bay was 1.87 V/m (747-243).

The report further quotes the RF immunity standards for avionics, in which it's quite clear that equipment approved prior to December 1989 might not reach a sufficient standard of protection (0.1 V/m test level), but equipment approved after that date P, Y, W, V, U and T require immunity to at least 5 V/m.

The CAA also tested the effect of RF on various bits of avionics:

Effects of Interference from Cellular Telephones on Aircraft Avionic Equipment (""http://www.caa.co.uk/docs/33/CAPAP2003_03.PDF)

In that test, they picked equipment certified to the pre-1989 0.1 V/m standard and exposed it to 25 to 50 V/m. In an experiment with results about as shocking as Newton's apple falling downwards from the tree, they discovered that sometimes the avionics didn't work properly ;) -- though in fact below 30 V/m they saw almost no effect.

This is a difficult topic, because relatively small failure rates (e.g. 1 per million flights) might be deemed unacceptable, so limited lab tests cannot necessarily provide useful data. But from the CAA papers, I certainly drew the conclusion that GSM phones were extremely unlikely to have an effect on avionics that justified the current prohibition and its resultant costs on business and quality of life.

[ChristiaanJ]

Ah, somebody throwing his teddy out of his cot..... :D

Back to serious matters.

I'm amazed nobody picked up on matt_hooks post.
Well, I can definitely say, without a shadow of a doubt, that a mobile phone left switched on CAN have an effect on navigational equipment, namely the NDB. This is in a light piston twin, but it proves that they can cause emissions in a wave band that might interfere with navigational equipment.He obviously did not make this up, and the link between "cause and effect" looks reasonably well established.

At first sight, there's something very wrong with this picture... an NDB transmits somewhere in the 190 - 1750 kiloHertz band, a cellphone somewhere around 800 or 1800 MegaHertz.

But.... most digital devices emit radiation on other frequencies as well, such as harmonics of the processor clock.
And if the cellphone ringer is driven with a nice squarewave, harmonics of that can very well get into the NDB band as well.

I feel this "spurious" radiation, totally unrelated to the nominal frequency the device works on, be it a cellphone or WiFi, is being neglected too much.

I remember very well doing EMC testing on a DAFS computer prototype (both conducted and radiated EMI)... we were disagreeably surprised by some of the unexpected frequencies and levels where we had problems.
The difference was of course, that we had to fix it to get certified.
Unlike your cellphone.

[Pax Vobiscum]

This topic has been discussed (if not 'done to death') in the past, but to save you the use of the search function, I'll repeat my couple of thoughts here:

1. At a (calculated) guess, 99% of flights carrying more than 50 pax will have at least one active cell phone on board, either through neglect or otherwise. (Sometimes the active cell phone has been in row 0 :) ) While this certainly doesn't prove that cell phones are safe, it suggests that any threat posed is relatively slight.

2. Now that the airlines have found a way to make money from them, cell phones will be allowed to be used on board. By installing an on-board 'picocell', the phones should be able to operate at their lowest power settings (<< 2W). At some point the picocell is going to fail in flight, and then all the active phones will swiftly ramp up to their max power settings in a futile attempt to contact the next nearest base station. This will provide an interesting test of the safety of these devices, but I'm not sure I want to be on board when it happens ...

[ChristiaanJ]

Pax Vobiscum,

Your 1.
I agree the threat is relatively slight, or we'd already have airliners dropping out of the sky like hailstones.
But, I think you will agree, that from both "anecdotal" evidence, and some of the info in the links quoted earlier, one has to assume a correlation between the use of PEDs (personal electronic devices) and anomalous behaviour of aircraft systems (mostly radio nav type systems, that would be the most susceptible).
And secondly, that establishing that the use of a PED was a contributing factor in a crash is well-nigh impossible.....

Your 2.
Picocells would keep down the 'baseband' power, but wouldn't reduce the spurious emissions I mentioned.
And yes, when such a picocell fails, I'd prefer to be in another aircraft, too.

[HeadingSouth]

most planes have already phones on board.

rather than doing EMI investigations which cannot clear any doubt yet cost a multitude of $$$ - why Not supporting the phones that are already on board instead?

saves as well using some $$$ for investigations whether miss business' mobile phone in seat 2A indeed caused the crash and took the lives of many a passenger...

[ChristiaanJ]

HeadingSouth,why not supporting the phones that are already on board instead?What do you call "supporting"?

I see two snags.

1. With cell phone and game console and computer add-on makers bringing out new models about every month, if not every week, a list of "approved" devices (which is what I assume you mean, correct me if I misunderstood) would be obsolete in six months.

2. While there are FCC standards for electronic devices, they assure at best they don't interfere too much with your television and automatic garage door opener.
So far as I know, there are NO standards in existence against which you could certify a PED as being approved for use on board an aircraft.

[matt_hooks]

ChristiaanJ, I think it's a fairly well known fact that mobile phones DO emit radiation on frequencies different to the actual transmission/reception frequencies. All one needs to do is stand a mobile phone near to a car radio whilst it is ringing to establish that. Now a car radio, whilst not safety critical, would not be particularly succesful if it were easily affected by EMI. The average electronic ignition system in your modern car causes quite scarily high energy levels, even outside the system, and yet in general car radio sets seem to be immune to this interference. Given this fact, it is quite concerning that a mobile phone can cause audible interference.

Granted, without thoroughly analysing the systems and emissions, one cannot say what component of the system is being affected adversely. It's quite possible that the interference is occuring in the (relatively) unshielded speaker lines rather than the internals of the system itself, but how well shielded are the transmission lines for navigational equipment? I personally am in no doubt that, in a light twin at least, a mobile phone on board CAN cause erroneous or misleading indications, I've seen it with my own eyes. Whilst this is not a direct safety issue, in that the interference is sporadic and short lived, there is always the possibility that it could lead to a pilot disbelieving his instruments and becoming disorientated.

As for a commercial environment, I think that in general the ability to use mobile phones on planes would be generally unpopular. However the ability to use wireless internet access might not prove so unpopular. The fact is, however, that the people who will decide (safety legislation aside) whether such services are supplied will be the airlines. Now some may take the view that it might be unpopular to provide such a service, but I would hazard a guess that many will find it hard to turn down another possible revenue stream. So if it can't be proved to be unsafe, I think we will probably see more widespread provision of such services onboard.

[Saint-Ex]

I witnessed one incident in a tri-jet when the autopilot was twitching the controls. A search of the cabin for active mobiles was made but it turned out to be the captain`s `phone in his flight bag. Once turned off, the autopilot gave no more problems. There was also an instance in my company on a B734 where a port engine surge was put down to a passenger in a window seat alongside the engine using his mobile. In reply to an earlier letter about fbw, an A320 was subjected to extreme exposure by a radar scanner centered on the avionics bay while configured in flight mode with engines running. I believe this was continued for several hours and no interference was recorded . This was one area where certification authorities really had to be convinced.

[airsupport]

IF they are anywhere near as bad as some of you are making out, why is it in some Countries like the USA, mobile (cell) phones are allowed to be used when on board the aircraft on the ground, at the gate but also during taxiing out and in?

As I said before I hope they are NEVER approved, but for comfort's sake NOT because of safety.

[matt_hooks]

Airsupport, safety is the only thing that will stop them being approved! Unfortunately most airlines see only the possible extra revenue stream, not the consensus of opinion that having them on board would be a bad thing.

[airsupport]

So what you are saying is that although they are NOT a danger to the safe operation of the flight, ban them on safety grounds anyway as it is the ONLY way to stop them?

The same would apply to babies and small children. ;)

[ChristiaanJ]

I witnessed one incident in a tri-jet when the autopilot was twitching the controls. A search of the cabin for active mobiles was made but it turned out to be the captain`s `phone in his flight bag. Once turned off, the autopilot gave no more problems. There was also an instance in my company on a B734 where a port engine surge was put down to a passenger in a window seat alongside the engine using his mobile. You've just added two more bits of 'anecdotical' evidence to a large database.
Why isn't this followed up more?
"Illegal", and simply unintentional, use of mobiles, and ohter PEDs is increasing all the time.
In reply to an earlier letter about fbw, an A320 was subjected to extreme exposure by a radar scanner centered on the avionics bay while configured in flight mode with engines running. I believe this was continued for several hours and no interference was recorded . This was one area where certification authorities really had to be convinced.Sounds like a particularly pointless exercise to prove/disprove anything. What finally comes out of a wx radar scanner is almost pure X-band radiation (assuming a recent one... are any C-band ones still around ?). Virtually none of that penetrates into an airframe.

We're talking about baseband interference (800MHz not being too far from DME frequencies), and spurious emissions (such as PEDs causing interfrence on NDB frequencies).

[West Coast]

"but also during taxiing out and in?"

Not meaning to be overly pedantic, but its only on the way in. The FAR's require them to be off to be able to taxi. Not to say its rigorously enforced as we all have seen people bent over out of the site of the FA's using them.

[airsupport]

I freely admit I do NOT know the regulations there, just while I was living and working in the USA some years ago, I did a lot of positioning flights as a passenger and on many of these flights passengers were using these mobiles (cells) both during taxi out and in.

[Contacttower]

We're talking about baseband interference (800MHz not being too far from DME frequencies)


Someone mentioned that his mobile had interfered with the DME in his aircraft on the GPS thread.

[Saint-Ex]

Sounds like a particularly pointless exercise to prove/disprove anything. What finally comes out of a wx radar scanner is almost pure X-band radiation (assuming a recent one... are any C-band ones still around ?). Virtually none of that penetrates into an airframe.

Christiaan, don`t know which type but Gordon Corps reckoned the most powerful signal they could find.