What would happen if all passengers of a Boeing 747 would using their cellphone during take-off

[TonKa]

I think it would fly anyway. If it was really that dangerous, why are you aloud to take a cellphone on board anyway?

If this subject has been discussed before, please sent me a link and ignore.

[Broomstick]

Most likely an uneventful take off.

The prohibition on using cellphones is because they might cause interference, not because they actually do on a regular basis. There is a little anecdotal evidence of some of effect at some times, but nothing that would crash an airplane. The concern would be mostly with navigational instruments - it would really be annoying to be off course while flying over, say, the Pacific and wind up far away from your intended destination.

[IAmNotSpartacus]

IIRC MythBusters did a story on this and found that some cell phones running on the 800MHz band may have a tendency to cause some issues but the final verdict was the myth was busted.

The reality is that pretty much everything in a critical system in a modern passenger airplane is double shielded from RF.

I can tell you that a number of my customers that fly helicopters use their cell phones in the air throughout the day and they're in much closer proximity to critical systems and none of them have crashed yet

[Machine Elf]

Originally Posted by IAmNotSpartacus

I can tell you that a number of my customers that fly helicopters use their cell phones in the air throughout the day and they're in much closer proximity to critical systems and none of them have crashed yet

Are helicopters commonly equipped with autopilot and fly-by-wire control systems (not a rhetorical question; I'm genuinely curious)?

I'm not aware of cell phone interference having caused an aircraft to crash, but there have been cases of interference in the past. It's very rare, but because of the typically large number of lives at stake, and the fact that we don't know for sure which cell phones might interact oddly with which aircraft electronic system, the prudent choice is to just tell passengers not to use any electronic device at all when the aircraft is below 10,000 feet.

[IAmNotSpartacus]

Originally Posted by Machine Elf

Are helicopters commonly equipped with autopilot and fly-by-wire control systems (not a rhetorical question; I'm genuinely curious)?

Autopilot yes it is out there. Fly by wire...iono.

It's also worth pointing out that aircraft have had two way radios, both AM airband as well as FM for a very long time

[proxl]

Actually, you folks who note about RF shielding are pretty much correct. However, that's really not why you can't use your cellphone below 10,000 feet. The primary reason is the same reason you can't use your laptop or your I-pod.

Below 10,000 feet (either on TO or land) is when an airplane is most likely to have an accident, and for everyone's safety, it's best to have people semi-attentive to the world around them, not to their toys. And it's best to have fewer potential projectiles in people's hands during that phase of flight.

[cantara]

Originally Posted by proxl

Actually, you folks who note about RF shielding are pretty much correct. However, that's really not why you can't use your cellphone below 10,000 feet. The primary reason is the same reason you can't use your laptop or your I-pod.

Below 10,000 feet (either on TO or land) is when an airplane is most likely to have an accident, and for everyone's safety, it's best to have people semi-attentive to the world around them, not to their toys. And it's best to have fewer potential projectiles in people's hands during that phase of flight.

This makes sense, but I thought it was about the RF interference. I know at work there can be problems if someone puts their Blackberry next to the phone. The people on the conference call hear buzzing on the line.

For that matter, when I listen with my noise-cancelling earphones, I pick up interference from my phone searching for Wifi, or (oddly) from the on-board communications on the commuter train.

[kayaker]

Originally Posted by proxl

Below 10,000 feet (either on TO or land) is when an airplane is most likely to have an accident, and for everyone's safety, it's best to have people semi-attentive to the world around them, not to their toys.

Just in case they needs me to fly the plane? Cool!

[mnemosyne]

Older planes may not be appropriately shielded against several hundred passengers' worth of electronic devices being in use. Many aircraft designs predate cellphone technology, and while there are fewer of these old planes in North America and Western Europe (and the remaining ones have possibly had their wiring replaced), in other parts of the world this might not be the case.

We tend to think of planes as being "modern" technology, but the original B747 is 30+ years old; the original B727 design is 40 years old, etc. It takes years to upgrade an aircraft (though of course, both these types have had avionics and other upgrades since), let alone design a new one, so technology capabilities onboard will always lag behind the latest and greatest land-based technologies.

Back in March I posted a quote from a current occurrence of wifi technology interfering in testing with onboard avionics. The article was reported from the Air Transport Intelligence news (received in the Curt Lewis Flight Safety Information newsletter on March 10):

Wi-Fi interference with Honeywell avionics prompts Boeing action

Honeywell Phase 3 Display Units (DUs) have shown themselves susceptible to "blanking" during airline electro magnetic interference (EMI) certification testing of wireless broadband systems (Wi-Fi) on various Boeing 737NG airplanes, prompting Boeing to cease linefit installs of in-flight connectivity systems across its portfolio, including widebody aircraft.

...

Fallout from the event is already occurring. Multiple sources tell ATI and Flightglobal that one of the conditions for STC is that 737NG operators place placards in the flight deck saying that Wi-Fi devices are to be powered off.
Another condition, say sources, is that 737NG operators are not to have DU 3 displays installed with the presence of in-flight connectivity systems, be they Wi-Fi or cellular-based.

Modern electronics, on a modern avionics package with the design intent of working together still caused problems. It's not a trivial problem to solve.

And quoting myself:

The problem occurred during certification, and not an actual in-flight event, but not all electronics are certified and approved for use in-flight. That's where the concern is; that some electronics - even ones designed to be used in flight - can interfere with avionics is a fact. Without knowing and individually verifying each and every device brought on board by passengers, the risk is there. The size of the risk is debatable, but air safety people tend to want to err on the side of caution.

[Smeghead]

Is the 747 on a treadmill?

[mnemosyne]

Too late to edit: as for what could happen... in the situation I quoted above, the pilots lose their flight displays, therefore lose airspeed, altitude, attitude, direction, engine status...pretty much every bit of information they need in order to fly the plane (ok, so there's the backup conventional compass and horizon, but the point stands). Best-case scenario, they manage without or systems come back online. Worst-case scenario, the plane crashes and everyone dies.


worst case...taking out people on the ground too...hitting an oil pipeline in the process...which ignites a nuclear powerplant...

[Zeriel]

There's also the problem on the carrier end--that is, my understanding is that a good bit of the issue is that cell phones at 10,000 feet will see multiple cell towers as approximately the same distance and cause a disproportionate network load as they rapidly drop and connect to new towers at several hundred miles per hour.

It's my understanding that a few companies are doing the research to certify on-aircraft cell towers that connect to the rest of the phone grid by satellite to alleviate those particular concerns.

[engineer_comp_geek]

As someone who designs electronic stuff for a living, I can tell you that cell phones can potentially interfere with all kinds of things. As a practical matter though, modern aircraft are designed to be rugged and reject this type of interference. I've been able to talk to a few pilots about this, and all of the big jet pilots I've spoken to have never had a cell phone cause an instrumentation or navigation problem (which would have been my first guess) but every single one of them complained that cell phones caused annoying noise in their headsets at some time or another.

On older small planes (your old Pipe Cub type of planes) I have heard of cell phones interfering with instruments as well as communication.

Pilots aren't idiots, so even if a moron on a cell phone makes them lose contact with air traffic control (which has happened) they have procedures where they can still land the plane safely, and in the case of instrument problems, they won't blindly follow one wonky instrument reading and fly into the ground. If the compass suddenly turns south they are going to know that the compass is out of whack and will use other methods to determine their direction.

Originally Posted by Zeriel

There's also the problem on the carrier end--that is, my understanding is that a good bit of the issue is that cell phones at 10,000 feet will see multiple cell towers as approximately the same distance and cause a disproportionate network load as they rapidly drop and connect to new towers at several hundred miles per hour.

In the early days of cell phones, an airborne phone could wreak all kinds of havoc on ground systems, not so much because they could reach multiple towers, but because they could reach multiple systems. The handoff between phone systems hadn't been designed to handle that and not only would huge amounts of resources get bogged down trying to handle it, but sometimes the ground systems would crash and everyone's calls would be dropped. Because cell phone users insist on using their phones no matter what (it often seems like the best way to encourage someone to use a cell phone in a particular area is to hang a sign saying you can't use it there) the cell phone companies just had to cope with it. Many improvements were made and airborne cell phones no longer cause major problems on the ground any more.

There is still the issue of airborne cell phones tying up communication channels on multiple towers simultaneously, which the FCC doesn't like because it wastes bandwidth resources. This also factors into the FCC's decision to forbid cell phones from communicating while in flight.

[Absolute]

Originally Posted by engineer_comp_geek

Pilots aren't idiots, so even if a moron on a cell phone makes them lose contact with air traffic control (which has happened) they have procedures where they can still land the plane safely, and in the case of instrument problems, they won't blindly follow one wonky instrument reading and fly into the ground.

Indications are that the Air France Flight 447 pilots did pretty much exactly that.

The pilots were certainly not idiots. But the problem with airplanes is that it only takes a few minutes of temporary idiocy to kill a few hundred people.

[Duckster]

FAA Factsheet - Cell Phones, Wi-Fi and Portable Electronics on Airplanes

91.21-1B - Use of Portable Electronic Devices Aboard Aircraft (PDF Warning) - Provides aircraft operators with information and guidance for assistance in the compliance to FAR Section 91.21.

You may/may not agree with the above, but there it is.

[TonKa]

I can understand the fact that a cell phone can interfere with all kind of electronic devices and for that reason it is not allowed to use them on board. What I don't understand is that I am allowed to take a cell phone on board while a nail clipper or a bottle of water will be confiscated. I guess it is too expensive to set up a system to take and return all the passengers cellphones. Is it money versus safety?

[hibernicus]

Originally Posted by engineer_comp_geek

On older small planes (your old Pipe Cub type of planes) I have heard of cell phones interfering with instruments as well as communication.

What would a cell phone interfere with on a Piper Cub? I can't imagine how RF interference could interfere with gyroscopic instruments. Maybe if you held it right beside the compass...

I never turn off my mobile phone or ask passengers to turn off their phones when flying a Cessna 172. I can't think of any flight-critical system that could be affected by the phone (other than some minor radio interference every 15 minutes or so). The safety benefit of having it turned on in case of emergency far outweighs any possible (in my mind, non-existent) risk.

[Broomstick]

Originally Posted by Absolute

Indications are that the Air France Flight 447 pilots did pretty much exactly that.

Preliminary results are that the Air France pilots did not have one wonky instrument but multiple readings on multiple instruments, in the middle of the night, in a severe storm. Very much a worst-case scenario.

Normally, having an instruments cease working or giving erroneous information just means the pilots go to a back up method of getting the information and the flight ends without anyone outside the cockpit having any clue there was something wrong.

[Absolute]

Originally Posted by Broomstick

Preliminary results are that the Air France pilots did not have one wonky instrument but multiple readings on multiple instruments, in the middle of the night, in a severe storm. Very much a worst-case scenario.

Normally, having an instruments cease working or giving erroneous information just means the pilots go to a back up method of getting the information and the flight ends without anyone outside the cockpit having any clue there was something wrong.

My understanding is that the pitot tubes were blocked by ice but that other instruments continued to function. The pilots may not have realized this, and it may have appeared to them that all the instruments were malfunctioning, but in fact they were all operating properly (including the artificial horizon). The entire disaster was caused by a single failure, of a single instrument / sensor, and the crew's subsequent mishandling of the situation due to poor training, fatigue, poor avionics design, etc. No other mechanical failures occurred.

See the latest interim report of July 29, 2011:

http://www.bea.aero/fr/enquetes/vol....let2011.en.pdf

[moejoe]

Small hijack for those who fly often. I'm thinking about how annoying it is when people on the bus or train yammer loudly on their cell phones for the whole ride, is that also the case on a plane these days? If so they must be even louder, and more annoying.

[engineer_comp_geek]

Originally Posted by moejoe

I'm thinking about how annoying it is when people on the bus or train yammer loudly on their cell phones for the whole ride, is that also the case on a plane these days?

No. During takeoff and landing cell phones and all other electronic devices have to be turned off, and when I took a flight last week they were quite strict about enforcing it. Once you are in the air, you can use cell phones in "airplane mode" which means you can play games on them and listen to music, etc. but you can't use them to talk and the transmitter is basically shut off.

As soon as you land and they allow the use of cell phones people start gabbing, but on the flights I was on, no one was obnoxious about it.

[Broomstick]

Originally Posted by Absolute

My understanding is that the pitot tubes were blocked by ice but that other instruments continued to function. The pilots may not have realized this, and it may have appeared to them that all the instruments were malfunctioning, but in fact they were all operating properly (including the artificial horizon).

Actually, the pitot tubes are also connected to things like the vertical speed indicator as well.

It wasn't that the instruments "ceased to function" but that they were giving readings that were erroneous. If they simply gave no reading at all that would actually simplify things. The cockpit recordings and actions indicate (to me, at least) that they did, in fact, know there was something wrong with the airspeed indications.

Another problem is that the airspeed indicator is pretty damn important - having a functional artificial horizon is useless if you aren't moving forward fast enough to stay in the air. Without reliable airspeed indication, maintaining flying speed does become more difficult. Seeing as they stalled the airplane they clearly did not maintain flying speed, and that is what killed everybody.

Normally, if one of the three of a set of instruments gives a reading different than the other two an Airbus will ignore the anomalous reading and rely on the other two instruments. Unfortunately, with the airplane in question, all three pitot tubes/airspeed indicators seemed to be giving different speeds, at which point the airplane relies on the humans to sort it out. Unfortunately, at night in a bad storm is not the best place to be doing that.

[TonKa]

MythBusters did a story on this

Would it be possible to watch this episode online? I looked for it on YouTube but no luck so far

[hibernicus]

Originally Posted by Broomstick

Actually, the pitot tubes are also connected to things like the vertical speed indicator as well.

I did not know that. In a light aircraft, the pitot tube is only connected to the airspeed indicator. The VSI works off the static pressure.

[Triskadecamus]

Naah.

The thing the FAA is really worried about is that because they have fiercely clung to this bizzare belief for so long now with absolutey not one single instance of even remotely likely interference with any operation of any airplane anywhere, admitting that now would be somewhat harmful to the reputation of the Agency as something other than a bunch of freakin' idiots.

Tris

[Absolute]

Originally Posted by Triskadecamus

Naah.

The thing the FAA is really worried about is that because they have fiercely clung to this bizzare belief for so long now with absolutey not one single instance of even remotely likely interference with any operation of any airplane anywhere, admitting that now would be somewhat harmful to the reputation of the Agency as something other than a bunch of freakin' idiots.

Tris

Have you ever heard interference from a cell phone through your computer speakers? Some cell phones do this more than others - GSM phones particularly. Sometimes it can be quite loud.

It is perfectly possible for this interference to disrupt digital signals in the aircraft, especially if those signals are already operating near their maximum noise tolerance (due to age, shielding damage, other interference, other malfunctions, etc.) Also, older cell phones and malfunctioning cell phones may transmit erroneously at much higher power, and cause more interference than your average iPhone. There's no practical way for airlines to inspect people's devices for overpowered transmitters, or other defects.

In most cases, the use of cell phones will cause no problems. The fact that most airplanes surely have some nitwit who doesn't listen to the announcement is proof of that. However, aviation safety is all about the abnormal cases. If the airplane has already experienced one systems malfunction due to a mechanical problem, then an additional systems failure caused some old relic piece of shit cell phone with a malfunctioning transmitter will make things that much worse, and that much harder for the pilot to figure out.

The fact that no such accident has happened yet is meaningless. The (commercial) aviation safety infrastructure is so good that the defining characteristic of most crashes is a novel, previously-unseen combination of circumstances that training/design was not intended to handle, or a circumstance previously considered too rare to worry about (the Airbus A320 that Sullenberger landed in the Hudson did not even have an official procedure for double engine failure).

I don't want to get into a debate with Broomstick, but my reading of the reports indicates that the sole failure of the airspeed indicators - and nothing else, not even the VSI - was enough to confuse the pilots into hand-flying the airplane straight into the Atlantic. Regardless of how well pilots can be trained, they are not perfect, and are just as vulnerable to panic, confusion, and other mental factors as anyone else. Banning the use of electronic devices at takeoff, and the use of transmitting devices at altitude, is a simple way to minimize the risk of failure.

How much is the reduction in risk? Quite minimal, I admit. But I don't see why I should accept any increased risk while flying so that the dipshit in the aisle next to me can call his mistress from 35,000 feet, or whatever.

[IAmNotSpartacus]

Originally Posted by Absolute

Have you ever heard interference from a cell phone through your computer speakers? Some cell phones do this more than others - GSM phones particularly. Sometimes it can be quite loud.

Bad example, you hear the noise of GSM (and only GSM, CDMA does not make the noise) because your speakers are cheap and are poorly shielded.

Aircraft, on the other, have a great deal of shielding in their components.

[Triskadecamus]

Originally Posted by Absolute

How much is the reduction in risk? Quite minimal, I admit. But I don't see why I should accept any increased risk while flying so that the dipshit in the aisle next to me can call his mistress from 35,000 feet, or whatever.

If it was minimal, but extant actual risk, at least one case of one unexpected reading on one instrument on one plane in one place would have been traced to the use of a cellphone. Yet that has never been reported anywhere.

If poltergeists were to jump up in the face of a pilot during take off, that too could have devastating consequences. What procedures do you recommend to avert this admittedly quite minimal risk?

This a bureaurocrats covering their asses because no bureaurocrats ever issue orders to stop worrying about things, or taking precautions. No one gets fired for not changing a policy, so that is the default.

Tris

[Absolute]

Originally Posted by IAmNotSpartacus

Bad example, you hear the noise of GSM (and only GSM, CDMA does not make the noise) because your speakers are cheap and are poorly shielded.

Aircraft, on the other, have a great deal of shielding in their components.

I assume it's actually not the speakers, which were quite expensive, but the cheap Radioshack cable connecting them to my computer.

And aircraft certainly do have shielding, although the amount of shielding used must be balanced with the need to conserve space and minimize the aircraft's weight. In any case, shielding can be compromised in any number of ways. As someone posted upthread, a brand-new glass cockpit display was shown to be sensitive to WiFi emissions during certification testing. It's lucky that this sensitivity was severe enough that it turned up in testing, and wasn't something more subtle that became apparent only on certain statistically-outlying units when used in commercial flights.

Aviation safety is all about not taking unnecessary risks. There is very little margin for error when you're thousands of feet above the ground, moving at hundreds of miles per hour, sometimes depending solely on your instruments that you may be in the process of troubleshooting to tell you basic information about the airplane (like whether the plane is flying straight and level, or in a descending spiral).

In all other modes of transportation, there is always the option to slam on the brakes and fix the problem once you've come to a stop, and you usually have the benefit of being able to look out the window to make sure that you're not heading for a bridge abutment or something in the meantime.

Airplane avionics are already ridiculously expensive because of the comprehensive certification process they must go through. It is perfectly reasonable to just tell the passengers to shut their phones off and depend on the flight attendants and nosy seatmates to catch 95% of the miscreants, rather than require avionics manufacturers to test their system for the case of "All 300 passengers using their cell phone at once, as permitted by law,", and ensure that their equipment continues to operate properly even when this case is combined with the current worst-case adverse condition required by certification.

In short: aviation safety is all about maintaining a safety margin. Allowing the use of passenger-operated transmitting devices (i.e. cell phones) in flight reduces that safety margin for very little practical gain.

Incidentally - even passive receiving devices are banned in flight because the receiver circuitry often operates at the same frequency as the transmitter, is necessarily not fully shielded (otherwise it would be unable to receive), and can therefore produce EM emissions as well. That's why you're not allowed to operate a police scanner on an airplane.

[Absolute]

Originally Posted by Triskadecamus

If it was minimal, but extant actual risk, at least one case of one unexpected reading on one instrument on one plane in one place would have been traced to the use of a cellphone. Yet that has never been reported anywhere.

If poltergeists were to jump up in the face of a pilot during take off, that too could have devastating consequences. What procedures do you recommend to avert this admittedly quite minimal risk?

This a bureaurocrats covering their asses because no bureaurocrats ever issue orders to stop worrying about things, or taking precautions. No one gets fired for not changing a policy, so that is the default.

Tris

So, this currently-banned activity should be allowed because the banned activity has not yet caused a crash? Flawless logic, there.

Because a crash is essentially the only conceivable way causation could be shown in a commercial aircraft. When was the last time you went on a commercial flight, and after landing the pilot announced "Sorry folks, we had a temporary glitch with the avionics during the flight today. We handled it just fine, but we're going to have to confiscate all your cell phones and send them to Washington so the NTSB can determine if they were operating during flight and can be proven to have caused it."

[Triskadecamus]

Yet in the face of this clear and present danger, the TSA, notably ultra concerned with the possibility that someone somewhere might ever interfere with a commercial flight have, by the example of their own policy, made clear that cell phones represent less potential risk to air traffic than Nail Clippers, which are not even allowed to be on the plane, except in checked baggage.

I cannot imagine what would possess anyone to defend this absurdity. Do you have a vested interest in the FAA? Are you a government policy authority? Admit it. It's bone stupid, always has been, and was put in place by a moron, ratified by a group of lickspitle yes men, and no one wants to admit it.

Tris

[Absolute]

And as much as I am astounded to find myself defending FAA bureaucrats, they are in a lose-lose situation here.

If they keep the ban in place because it's the safe thing to do, people take their uninformed anecdotes, assumptions and proclamations and accuse them of being overly cautious.

If they decide to allow cell phones and an accident is eventually proven to be caused by one, you can bet some of the very same people will be all over them, criticizing them just as harshly for not doing their duty to protect the flying public.

I mean, hell, imagine the circus that would result if the ban was lifted, and an airliner crashed the next week? Though it would surely be the result of some unrelated factor, it would take months, perhaps years before that could be proven, and the resulting PR nightmare would cripple the FAA and prevent actual useful work from being done.

If a Republican president were in office, morons on this board would be criticizing the FAA for being in bed with big business, compromising safety for commercial reasons, and ascribe some financial motive to the rule change (e.g. increased revenue for the cell phone companies, increased revenue from business customers by the airlines, who knows). If a Democrat were in office, a separate set of people (still morons, though) would be criticizing the FAA for being incompetent, poorly-run, improperly managed and blame the administration and existence of regulations in the first place for allowing this disaster to take place.

Actually, I suspect that these groups of people are so unencumbered by logic that they would make these points regardless, as they do for any negative event of any type.

[engineer_comp_geek]

Originally Posted by Triskadecamus

The thing the FAA is really worried about is that because they have fiercely clung to this bizzare belief for so long now with absolutey not one single instance of even remotely likely interference with any operation of any airplane anywhere,

What exactly are you calling "interference" in this case? Because cell phones have caused at least one instance of the plane completely being unable to speak to the controllers that I am aware of (and this isn't something I follow so there easily could be more) and has caused numerous instances of noise in pilot's headsets, which is not exactly something that will make the plane immediately fall out of the sky but certainly seems like enough justification to me to continue the ban on transmitting devices during takeoff and landing.

And the FCC and FAA aren't just blindly clinging to some old story so that they'll look good (that part seems like conspiracy woo to me). They re-evaluated all of this a few years ago, taking into consideration changes in technology and aircraft, and after a rather thorough study they decided to keep the bans in place.

(For the record I work in industrial control, and have absolutely no ties to the FAA, FCC, the airlines, or anyone else involved in this)

[Absolute]

Originally Posted by Triskadecamus

Yet in the face of this clear and present danger, the TSA, notably ultra concerned with the possibility that someone somewhere might ever interfere with a commercial flight have, by the example of their own policy, made clear that cell phones represent less potential risk to air traffic than Nail Clippers, which are not even allowed to be on the plane, except in checked baggage.

I cannot imagine what would possess anyone to defend this absurdity. Do you have a vested interest in the FAA? Are you a government policy authority? Admit it. It's bone stupid, always has been, and was put in place by a moron, ratified by a group of lickspitle yes men, and no one wants to admit it.

Tris

Now your argument depends on the TSA being logical, rational and consistent. Another winner.

The reason I'm wasting my time writing these posts is because I'm an engineer and I analyze and design complex systems for a living, which sometimes involves failure analysis. Professionally, nothing annoys me more than people who think that, because something is simple in their simplistic view of the situation, it should be simple in reality.

[Triskadecamus]

Originally Posted by engineer_comp_geek

What exactly are you calling "interference" in this case? Because cell phones have caused at least one instance of the plane completely being unable to speak to the controllers that I am aware of (and this isn't something I follow so there easily could be more) and has caused numerous instances of noise in pilot's headsets, which is not exactly something that will make the plane immediately fall out of the sky but certainly seems like enough justification to me to continue the ban on transmitting devices during takeoff and landing.

Could you find me a link to a report of that sort of event, please?

Thank you.

Tris

[Absolute]

Posted too soon.

Additionally, few things annoy me more than other people compromising my safety because of their uninformed opinion that it's "not a big deal".

I'm also a (non-commercial) pilot, and I have an interest in aviation safety (as does any sane pilot of light aircraft, which are statistically about as dangerous as motorcycles). While they can be somewhat overbearing at times, it is clear to me that the only reason commercial aviation (i.e. airline travel) is as safe as it is is the hard work, dedication and ability of the very people in industry and government that you are so ignorantly insulting.

[Zeriel]

I'll be a little more overt than I was in previous posts. I work for a company that writes electromagnetic simulation software. We have had numerous projects related to the safety of cell phones on airliners (including researching the placement of a cell tower antenna onboard to mitigate the OTHER problem with cell phones on aircraft--that is, over-stressing the ground-based towers with cellphones moving too rapidly or seeing multiple towers simultaneously.)

The cumulative signal strength and interference potential from a few cell phones is minimal, but the potential from a significant fraction of the people aboard using them or even leaving them on is actually quite astounding and a lot larger than you'd expect--I mean, consider they're all operating in a moderately shielded electromagnetically reflective metal tube, for starters.

I decline to be more specific, as I enjoy being employed.

[ricksummon]

If electromagnetic interference from cell phones can, indeed, disrupt aircraft instruments, why haven't any terrorists used them?

Nobody move! I've got a phone, and I'm NOT AFRAID TO USE IT!!

But seriously, a terrorist could probably rig up some kind of dedicated jamming device disguised as an innocuous device and simply stuff it in his carry-on luggage. What defense would a pilot have against such a scenario?

[Broomstick]

Originally Posted by ricksummon

If electromagnetic interference from cell phones can, indeed, disrupt aircraft instruments, why haven't any terrorists used them?

Nobody move! I've got a phone, and I'm NOT AFRAID TO USE IT!!

But seriously, a terrorist could probably rig up some kind of dedicated jamming device disguised as an innocuous device and simply stuff it in his carry-on luggage. What defense would a pilot have against such a scenario?

His brain.

No, seriously, while instrument failure is no joke one of the reasons the human is sitting up front is to deal with failures of that sort. Airliners with complete power or massive instruments failures have landed safely due to the timely actions of the pilot(s) involved. Such a jamming device is a way to cause great inconvenience and stress but it is in no way a reliable means to crash an airplane.

[SciFiSam]

Originally Posted by Triskadecamus

Yet in the face of this clear and present danger, the TSA, notably ultra concerned with the possibility that someone somewhere might ever interfere with a commercial flight have, by the example of their own policy, made clear that cell phones represent less potential risk to air traffic than Nail Clippers, which are not even allowed to be on the plane, except in checked baggage.

I cannot imagine what would possess anyone to defend this absurdity. Do you have a vested interest in the FAA? Are you a government policy authority? Admit it. It's bone stupid, always has been, and was put in place by a moron, ratified by a group of lickspitle yes men, and no one wants to admit it.

Tris

Nail clippers are allowed in carry-on luggage on planes.

[Zeriel]

Originally Posted by ricksummon

But seriously, a terrorist could probably rig up some kind of dedicated jamming device disguised as an innocuous device and simply stuff it in his carry-on luggage.

I'd honestly be surprised if something with a battery big enough to be significant could pass security, but I'm not sure about how much total power output you'd be able to get from something the size of an extended-cell laptop battery (about as big as I think you'd be able to get aboard these days).

The two main problems with this tactic are 1) it's "only" going to jam up the instruments/radio at worst, which is not enough to take down an airliner except on approach in bad weather, and 2) the timing of their use would have to be such that the pilot couldn't wait out the battery of the device (which is going to be draining at a relatively prodigious rate).

[LSLGuy]

Tris: You're wrong, period, amen.

The TSA has a set of responsibilities under the law. Those responsibilities do NOT extend to aviation safety, only aviation security. So the fact the TSA used to prohibit nail scissors (they never prohibiuted nail clippers, and they do not now prohibit nail scissors) is irrelevant to any regulation or lack of same on cell phones. If there was a way to hijack or reliably crash an airplane with a cellphone, they too would likely be prohibited by TSA.

The FAA has regulatory authority over aviation safety. As the links provided by Duckster explains, the situation with cell phones (all PEDs really) is complex.

Prior to the advent of PEDs, the attitude of the FAA is that absolutely everything is prohibited until a formal testing program has proven it's safe to umpteen decimal places. The airplane manufacturers can't even change the brand of #10-32 machine screw or light bulb they use without formal engineering proof that the new ones are as good or better than the old ones.


When the first PEDs ("transistor radios") came out in the 60s, there was a very real engineering concern because the IF stages of AM & FM radio receivers operated on very similar frequencies to the primary navigation system of the day, VOR. The signals inside the coax running from ground transmitters 150 miles away into external antennas then into aircraft radio receivers are measured in microvolts. That a passenger's radio's electronics could be situated a couple feet away from antenna cabling and be pumping out interference stronger than microvolts is very plausible. In fact it's happened.

So radio receivers were prohibited.

Fast forward 50 years. Now we have lots of personal transmitters. And nobody in the consumer electronic business is doing anything to certify their stuff as safe for aircraft. And although the latest aircraft & avionics are built with PEDs in mind, all the old systems are still there too.

Only the 787 & A380 designs were begun after 3G cellphones became ubiquitous. Any other aircraft type (i.e. every airliner in the world today except a few dozen A380s) was designed before 3G cellphones existed. Most of them were designed before any cellphones existed.

Interference happens. We see it frequently. Because we can't positively establish causation, nothing can be reported or done. The most significant inflight hazard is that the navigation system used worldwide for low-weather landings (ILS) is 1950s technology. The frequencies & signal formats are what they are. They are susceptible to PED interference. Hence the specific prohibition to turn absolutely everything off for arrival.


The FAA is in a crack. They have regulations which recognize the threat, but they shift the burden of safety onto the carriers. Why? Because they know as a matter of legal authority and practical politics that they can't mandate the level of testing & certification required to prove that your personal collection of devices is safe to umpteen decimal places, or require you to leave them at home if they aren't on the approved list.

The airlines are in a crack. They can't practically prevent people from bringing PEDs onboard in checked luggage, carryon luggage or on their person. They don't want to piss off their customers. They want the aiplane manufacturers to design interferance-proof airplanes. That's -proof, not -resistant.

As a matter of engineering reality, the manufacturers cannot make interference-proof airplanes until they determine what they're making them -proof from. And at the rate consumer electronics advance, thats logically impossible. A fresh aircraft design started today will be delivered in about 2020. And be in use to 2060.

If we could get worldwide regulation on the permissible nature of PED transmissions both deliberate & inadvertant, that would at least give the avioncs engineers a target to aim at. Fat chance of that.

Finally, passenger's attitudes that this is all some scam to sell airphone use, or some bureacratic CYA are a large part of the problem. If I was King we'd treat somebody firing up a PED at a prohibited time or in a prohibited mode about the same as we treat somebody who starts playing with matches.


This is a tough problem. if I was King we'd have an effective RF interference receiver which could alert us that something unexpected is transmitting someplace aboard our aircraft. And the FAA would be running a comprehensive data gathering program to for us to report these occurrences.

In reality, everybody's looking the other way & hoping the next generation of nav systems can be designed to be close enough to -proof that we don't care what gizmo's people use. And that the odds are good enough that no accident will happen in the 20+ years it will take to deprecate the existing nav systems worldwide.

I will say the odds are exellent that no accident will happen in the meantime whose investigation will blame PEDs. But there is almost certainly going to be an accident which should be blamed on the PED which will cause it.

[LSLGuy]

Late add: Or has already caused it.

[Triskadecamus]

Still waiting on the link to a report by anyone, anywhere, anytime that a cell phone caused any problem on any airplane.

Tris

[engineer_comp_geek]

Originally Posted by Triskadecamus

Still waiting on the link to a report by anyone, anywhere, anytime that a cell phone caused any problem on any airplane.

That's easy. I found this in about 30 seconds of searching.

Effects of Interference from Cellular Telephones on Aircraft Avionic Equipment
From the Civilian Aviation Authority (UK)

1.1 Between March 1996 and December 2002, the number of aircraft safety-related
incidents that cited cellphones as a factor, as reported to the UK CAA in accordance
with the UK Mandatory Occurrence Reporting legislation, totalled 35.
1.2 The reports linked interference with effects including:
• False warnings of unsafe conditions (e.g. baggage compartment smoke alarms);
• Distraction1 of the flight crew from their normal duties;
• Interrupted communications due to noise in the flight crew headphones;
• Increased work load for the flight crew and the possibility of invoking emergency
drills;
• Reduced crew confidence in protection systems which may then be ignored
during a genuine warning;
• Malfunctioning of multiple systems essential to safe flight.

From here (warning - PDF):
www.caa.co.uk/docs/33/CAPAP2003_03.PDF

The FAA and FCC probably keep a similar list but I didn't find it in my brief search.

[engineer_comp_geek]

There is also this, from ABC news. I did not track down the original report that this is based off of.

A report by the International Air Transport Association, a trade group representing more 230 passenger and cargo airlines worldwide, documents 75 separate incidents of possible electronic interference that airline pilots and other crew members believed were linked to mobile phones and other electronic devices. The report covers the years 2003 to 2009 and is based on survey responses from 125 airlines that account for a quarter of the world's air traffic.

Twenty-six of the incidents in the report affected the flight controls, including the autopilot, autothrust and landing gear. Seventeen affected navigation systems, while 15 affected communication systems. Thirteen of the incidents produced electronic warnings, including "engine indications." The type of personal device most often suspected in the incidents were cell phones, linked to four out of ten.

[Triskadecamus]

Thank you for the links. I will be reading them this evening, and will respond when I have finished.

Tris

[Triskadecamus]

Read the links. The second one seems pretty close to being anecdotes from parties with probable conflicts of interest, in a scientific sense. All alone it would not convince me. However, the first link was definitely meticulous in its experimental design, and within reason in its conclusions. It seems to me now that the possibility exists in “worst case” scenarios that actual interruption to flight systems is possible from cell phones. New communication devices seem even more likely to cause problems, so I assume the problem is of no concern to phone designers and manufacturers.

This causes me to wonder, why cell phones are allowed on flights at all. But I accept that the actual risk does exceed that of poltergeists. I also wonder why airport warnings don’t include at least references to supporting experiments.

So, my ignorance is fought. Thank you.

Tris