Bringing down airliners isn't supposed to be hard. They aren't military hardware. There are many feasible threats against airliners that are within the reach of groups with smaller than government budgets.
Go have a look at some of the previous Movie-plot threat contests from Schneier. EMP devices aren't easy. Go look at the aforementioned contests: you'll see a variety of much less difficult methods.
Better protection of aircraft systems from outside interference will certainly happen/is certainly happening, but this would be an asinine justification for it. Far better reasons include the billions of small but powerful radios and other electronic devices that get used on airplanes each year.
Governments always "take these threats seriously" because threats=money for useless clock punchers not engaged in productive activity for society.
The referenced April 1 New Scientist article serves up a deliciously confused and obfuscated perspective that seamlessly entwines EMP & Electronic interference as though they were one. One may see it most clearly as a very indirect spoof on the Global Warming froufrou, IMHO.
Lest someone take pocket-EMP generators on as a challenge, one will not attempt to discuss specifics of electromagnetic mischief in this forum, other than to point out that EMP efects typically derive from very High-Energy processes and those, or their sources, generally are quite conspicuous by their presence and support needs, so not well-suited to covert and portable applications done on a budget.
Along with simple, ancient methods like shielding and proper technical design of aircraft systems, the property that makes vehicles and systems most successfully resistant to attacks of various sorts is "Robustness" in the way that critical component, subsystem, and system failures are handled when they occur - whatever the reason. Early aircraft had little or no redundancy and hardly any ability to endure critical failures, but they did not have very many components. With advancing time and especially growing virtuosity in use of electronics and computing to manage things at the nuts and bolts level, aircraft systems using billions of working components are increasingly made to "fail soft" when problems occur, so that operations may continue in a degraded but adequate manner after even very serious problems. The human crew members are, of course, the ultimate fail-soft tools in the program.
Newer aircraft are likely to be much more resilient than older ones - except in cases where thicker pieces make the critical difference. New technologies may have other vulnerabilities, however, and may have different unperceived failure modes that can make for new risk exposures. Very electronic and very digital aircraft may prove more vulnerable to random operating errors and other sorts of internal functional confusion caused by external means and threats, by operator errors, and also later in life by accumulating effects of incomplete or inappropriate maintenance.
Wouldn't an EMP device with enough power to affect an aircraft INSTANTLY as it passed over you at a fair height (let's be honest, you wouldn't be standing at the fence with one) be rather dangerous to the person operating it?
Let's just look at what we need. To produce a field strength of E volts/metre at a distance d, E = (square root of 30 times the power) /distance.
The IEC (International Electrotechnical Committee) standard for light industrial and domestic premises suggest equipment should be immune to 3volts/ metre. Sensitive equipment, such as safety of life radios on ships and pacemakers, should be immune to 10 volts/metre. (For pacemakers, IEC 60601).
10 v/m at 1 km needs 3.33Megawatts. Lets say we can charge a capacitor to 1000 volts. We need to draw 3300 amps for a period of time. That time has to be long enough to get appreciable energy into the bandwidth of the radio. Let's assume 10MHz wide. Now to get a pulse rising to 90% of its maximum value, it will need a width of, as a minimum, (from 0.4 = bandwidth times risetime) of 40ns. To get 3300 amps for 40ns with a drop of 10% means a capacitor of about 26nF. BUT the series resistance must not exceed 30 milliohms.
So we start needing bigger and special capacitors. Then we have to consider the radiator efficiency and how we couple the energy into it.
So there are far easier and more practical ways to cause major disruption from relatively small devices, and, needless to say, no way am I going into further detail here. So far, terrorists haven't shown themselves to be that technically advanced, and no way will I help the fatherless wotsits - well, except to put a rope around their necks and give them a two foot drop.
Modern commercial aircraft are now being spoken off as being immune to 200 volts/metre.
You could say the same about explosives. Custom is for the operator to retire to a safe distance.
The NS article does mention, though, that EMP weapons are either house sized Marx generators or small nuclear weapons, not something a fake spotter might have in his rucksack.
And there we have the issue of a safe distance being so far away he/she would have trouble setting the thing off at exactly the right time.
Hmmm, what could you fit in the back of a 40 tonne truck? Could it be possible that something could be made that size? They would hardly care about the truck going BOOM if/when things overloaded, and I ain't talking about using a nuke of any kind, but would it be possible for someone to build a device into that sort of size and be driving it past the perimeter fence as any aircraft is coming into land? Sure, the driver would be microwaved and cooked before the wagon blew itself apart, but the kind of people who would do that nowadays would happily do that for the 70-odd Virginians that would greet them afterwards. They would get the effect they desired though, an aircraft suddenly going down, the closure of airports, every truck suddenly becoming a suspect vehicle............
you are correct that 200V/m is not an uncommon HIRF requirement for critical systems on numerous modern aircraft, with significantly higher values for higher frequencies but pulse modulated....but this is getting a bit nerdy for JB.
Personally I cant see it ever happening as the result of some homemade transmitter
I believe the Spooks were developing a device. They want to get it down to the size of a suitcase but last time I read about it it had just been reduced to the size of a 40ft container. I'll see if Googoo returns any hits.
Location: South of the North Pole, north of the South Pole...
I more or less agree with the opinions of previous posters, that 'the threat' from currently available technologies for 'home-made' EMP devices is largely academic. The simple attempted procurement of some of the composants involved (leaving aside the subsequent energy requirements) required to directly attack even one modern large aircraft would surely have attracted the attention of anti-terrorism measures already in place.
The only 'truly efficient' method of launching an effective EMP attack is stillthe good olde nuclear warhead, detonated at high altitude. Where just a minute fraction of the total energy available is converted into an electro-magnetic pulse with deadly consequences to all 'non-hardened' objects (that includes most civilian airliners; civil airports; civilian power-generation and transmission infrastructure; your landline phone / mobile phone / satellite TV / internet provider; the PC, TV, washing machine / fridge / freezer etc. at home) which would all cease to function and be rendered obsolete.
Today, we're 10 years on from that US Congress' investigation into EMP that I've linked to. Perhaps, more than for any other reason, that is why today, our governments always remonstrate so much when confronted by the possibility that any 'rogue' nation, such as N. Korea or Iran may possess even a single nuclear warhead that they could launch on a ballistic missile...?!
Well before any global warming / cooling have possibly rendered huge expanses of North America and Northern Europe uninhabitable towards the end of this century, many developing and even very small 3rd World countries will by then have also developed much more efficient technologies. I reckon the USA / Russia and maybe already China could probably today 'black-out' half of the Northern hemisphere by using a small Hiroshima-sized nuclear device if they wished to (except that would be self-destructive).
In fact, all we're waiting for ca. 2030 is for some (ex. GWB era) USA redneck to threaten to bomb the A-rabs (except the Iranians are Persians) "back to the stoneage" and for some crazy Iranian mullah to accede in kind...?!
Just bear in mind that every day, airliners are subject to field strengths of around 1000 to 5000 volts/metre as they land and take off at Heathrow. The 23cms radar there puts out about 1GW - 1,000,000,000 watts effective radiated power. In short pulses. The average power would still cook a frozen chicken pretty quickly...
(Heathrow Director, is that how you heated up your dinners?)
Yet everything keeps working......
Last edited by radeng; 10th Apr 2009 at 19:33.
Reason: missed word
The article is bollocks squared and cubed. I won't repeat what has already been stated above, except a few observations.
Any carry-on device would be quite conspicuous. The Marx generator is by necessity rather large, the compressed flux device uses a significant amount of explosive, and both need a powerful battery and some electronic bits and bobs. Hardly something you casually carry in your ruck-sack and pass through the x-ray scanner without rising an eye-brow or two.
Ground based emitters might be focused, but would be huge and need to be rather close to the target. As noted above, unlikely to make any lasting impression on the avionics.
Now this has me worried:
basic EMP generators can be built from descriptions available online, using components found in devices such as digital cameras.
Of course they can, and I've done it, but the output is insignificant for the purpose. Good for making some sparks and bangs, but not much more. Annoys the dog too.
Still, if this gets the attention of the paranoid we may be in for some hassle. Oh well, I can always fall back on the 35 mm SLR.
We can go to 10 or 20kV if you like. But it drops that current by a factor of 10 or 20, so it's still substantial. For a 'portable' generator, you'll need a slightly physically begger HV supply (because of insulation, and it will take some time to get the energy into the capacitor. The other point is that the , series inductance and resistance of the capacitor must be very low, and getting the series inductance down in capacitors with lots of insulation isn't all that easy. This why the capacitors used in setting off the explosives in nuclear weapons are rather special, and have export control limitations - there was a case some years back of a guy jailed for illegally exporting such capacitors - if I remember correctly, to Iraq..
Then there's the antenna requirement. A lot of work has been carried out in the last few years on Ultra Wide Band antennas but not generally on ones capable of handling that much power - you have to watch things like setting up a coronal discharge from the ends.
You also need a pretty good switch to switch that power in that sort of time. It's not a little reed realy!
As airship says, the most practical is the high altitude nuclear explosion.
So I go down the route of believing that there's lots of other more likely ways.