View Full Version : Are home-made EMP devices a threat to commercial aircraft?

9th Apr 2009, 16:27
New Scientist seems to think so: Aircraft could be brought down by DIY 'E-bombs' (http://www.newscientist.com/article/mg20227026.200-aircraft-could-be-brought-down-by-diy-ebombs.html). (Yes, I saw the date, but I don't think it's one of "those" articles, at least not on purpose.)

Me, I suspect Jet Blast is the right place for such speculation. In the http://www.pprune.org/jet-blast/309369-ba-777-speculation-thread.html, 2.22% of PPRuNers thought EMP was behind the BA038 incident. :ooh:

tony draper
9th Apr 2009, 16:35
I'm still working on me Directional Feckion beam.:rolleyes:

9th Apr 2009, 16:41
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.

Lon More
9th Apr 2009, 16:43
Lasers (http://news.bbc.co.uk/1/hi/technology/7990013.stm) on BBC News last night

9th Apr 2009, 17:17
Lot easier to use a SAM.

9th Apr 2009, 17:25
Lot easier still to stuff something upleasant in a cart. Worked in a place dealing with rotables once & was struck by how lax that side of things is.

9th Apr 2009, 17:49
Hey Sprogget, you still shopping at Tescos ?

(Lot easier still to stuff something upleasant in a cart)

9th Apr 2009, 18:55
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.

9th Apr 2009, 20:36
Just a thought

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?

9th Apr 2009, 21:40
be rather dangerous to the person operating it?

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.

9th Apr 2009, 21:41
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.

The SAM is more likely.

9th Apr 2009, 21:50
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............

Sorry, thinking out loud

9th Apr 2009, 22:01

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

9th Apr 2009, 23:36
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.

Here:- New EMF Weapon: Vehicle-Mounted Active Denial System (V-MADS) (http://learnaboutemfs.com/2007/12/17/new-emf-weapon-vehicle-mounted-active-denial-system-v-mads/#more-37)
and:- US Electromagnetic Weapons: To Invade a Person's Body Without Their Consent | Sabbah (http://sabbah.biz/mt/archives/2007/01/06/us-electromagnetic-weapons-to-invade-a-persons-body-without-their-consent/)

None of this stuff is recent:- IEEE Spectrum: The Dawn of the E-Bomb (http://www.spectrum.ieee.org/archive/1543)
(and following pages)


10th Apr 2009, 14:32
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 still the good olde nuclear warhead, detonated at high altitude (http://commdocs.house.gov/committees/security/has280010.000/has280010_0.HTM). 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...?! :uhoh:

10th Apr 2009, 20:31
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......

Captain Stable
10th Apr 2009, 22:19
I'll go with radeng - he clearly knows his stuff.

Trouble is, as soon as Jacqui Smith gets hold of this thread, she'll have everyone at the security gate surrendering anything that contains any sort of battery from their carryons.

11th Apr 2009, 03:15
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.

11th Apr 2009, 10:10
Radeng, why are you charging to only 1kV in your theoretical design? 30nF /40kV caps are only around $60 in quantity.

11th Apr 2009, 12:03

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.

11th Apr 2009, 13:45
So, [email protected] are visible, while radio waves dissipate over distance (square law). What about a coherent microwave source... I know some agencies are looking at MASERs (http://www.au.af.mil/au/awc/awcgate/cst/occppr10.htm) as weapons, but I doubt that a home hobbyist could make one with sufficient energy to do anything.

(A beam of a particular amplitude carries energy proportional to its frequency, which is why X- and Gamma rays are so hard to produce, and so dangerous if you do produce them. Microwaves have a lower photon energy than visible light.)

12th Apr 2009, 13:50
Decent radars these days are coherent - they need to be because they use phase information (Ground based weather radars are very dirty - still using magnetrons and far more spectrum than they need). However, even with an antenna the size of that nice big one at Heathrow, 250 or 500kW is about all you can have CW - you can have a lot more in pulsed conditions. In the end, even if you have a large antenna, all you do is concentrate the power into a narrow beam - tha is what lasers do. You can have a very high field strength because of antenna gain, but you can't extract more power than went into the antenna.

Now a high power CO2 laser as used for cutting metal could be a danger at some distance, but I don't how much dispersion you get. One of those in the wrong hands could be very nasty.

A SAM would probably be easier to get.

12th Apr 2009, 23:15
You mean all those lightning protection mods we did on the FADEC wiring ADs and the SSFR88 mods we've done on the fuel tank harnesses was a complete waste of time? Damn! :rolleyes:

13th Apr 2009, 08:14

you try carrying a cum-nim cloud in your pocket! Or your brief case.

There's a hell of a lot of energy in lightning - more than you can easily produce ina portable or semi portable container.

13th Apr 2009, 08:31
you try carrying a cum-nim cloud in your pocket! Or your brief case.

There's a hell of a lot of energy in lightning - more than you can easily produce ina portable or semi portable container.

Yes, but.... there's energy and there's information.

A parcel of energy aimed in a certain way, based on certain information..... may be compared to a projectile aimed at the vulnerable heart of the target. The total power of the insult may be relatively small, but the overall effect of it might be considerably magnified by the specificity of direction and timing.

Therein lies a rub - for threat management in the non-mil case.

green granite
13th Apr 2009, 09:02
Now a high power CO2 [email protected] as used for cutting metal could be a danger at some distance, but I don't how much dispersion you get. One of those in the wrong hands could be very nasty.

For a 2KW CO2 laser you'd need a small truck to carry it and something like a 10KW supply, mind you it's 15 years or so since I worked on such beasts so they may have improved a bit.

General consensus then was for a weapon you needed a chemical powered laser.

13th Apr 2009, 16:43
What were those man carried IR SAMS the US gave to Afghan insurgents when the Afghans were fighting the Russians? Are there likely to be any of those left in working order?

If so, I'd say that's more of a danger. But of course, after all these years, it's likely that they're non-operative. Like Shrike ARMs.

14th Apr 2009, 01:02
Stingers, starting around 1986. One would imagine the battery coolant unit is the lifed item, and that life would be pretty long.

14th Apr 2009, 03:20
If EMP devices are not a threat to commercial aircraft, then pray tell me why is a mobil phone that is switched on in flight such a threat to the navigation systems?

14th Apr 2009, 04:10
If EMP devices are not a threat to commercial aircraft, then pray tell me why is a mobil phone that is switched on in flight such a threat to the navigation systems?

We could compare this to some age old catapults used in 1066 being used to fling frozen chickens into the flight path of heathrow departures - there sure as hell is a risk of bringing down a plane, it may not be likely but do you really want to find out ?

In seriousness from what I understand you would have to approve each device against the shielding around the equipment to make sure its not going to cause a problem unless you have already ascertained the shielding caters for above the permitted transmission levels from such devices.

14th Apr 2009, 04:46
In seriousness from what I understand you would have to approve each device against the shielding around the equipment to make sure its not going to cause a problem unless you have already ascertained the shielding caters for above the permitted transmission levels from such devices.

And that, per my earlier comment in this thread, is exactly where "robustness" at recovering from faults, whether internally or externally caused, is the technological key to getting home safe. Not all threats can be avoided, but one may plan ahead to mitigate their negative effect with clever efforts to gracefully survive them.

14th Apr 2009, 07:56
The mobile 'phone emits various discrete frequencies all the time: not all of them are intended (the others are officially termed 'unwanted emissions in the spurious domain), and those can casue problems. plus EMP tends to be a one off event. there are big differences in designing stuff to be EMP hard and EMC immune

14th Apr 2009, 08:51
Everything electronic in an aeroplane registered for commercial air transport must be tested and certified to meet specific standards called TSOs. Your average mobile phone is not. Should you possess a mobile phone certified to a specific commumications equipment TSO standard, and you happened to be carrying a copy of the TSO in your pocket, you could use your mobile phone in an aeroplane. The onus of proof is upon the mobile phone user and not upon the commander of the the aircraft.

14th Apr 2009, 09:46
Re Mobile phones on Planes

I can't find the link now [it's a couple of years old at least] but some proper scientific tests were done in the UK regarding the effect of mobile phone handset transmissions on avionics and some effects were noticed although they were small. [I think primarily it caused false deflection in VOR instruments but again this is from memory so I could be wrong].

Found the Link (http://www.caa.co.uk/docs/33/CAPAP2003_03.PDF)

14th Apr 2009, 10:35
In the good ol days, radios used to be predictable, orderly devices with their waves wiggling endlessly in a simple way.

These days, radio signals are deliberately designed to be exactly like electronic noise - it actually makes 'em work better. A byproduct of that, however, is there's no predicting what kind of noise patterns may come out of them - very like in-laws, really.

14th Apr 2009, 11:53
very like in-laws, really


I remember reading one other reason why cellphones are banned on flight is because they can 'see' a larger number of cellphone towers, and they risk overloading the network by connecting to many at once. How true is that?

14th Apr 2009, 12:35
It's one consideration. The radiation pattern of ground stations is somewhat planar: the plane is horizontal. The phone itself is pretty omnidirectional. There's a maximum phone range which, depending on technology (older is better) and market, is possibly somewhat less than cruising altitude. because of the ground station radiation pattern, the nearest stations may not be the ones that detect the signal. That can confuse routing algorithms. There are also limits on hand-off speeds between cells, and finally doppler plays a small role. So yes, a phone could work, but don't be surprised if it doesn't.

I can demonstrate this nearby: my phone works at sea level around 4km from the shore, but it stops working some 600 meters up the hill inland, approximately 2km from the nearest antenna. It also clearly steps up its transmitting power to try to compensate, because the battery goes flat several times faster. The networks in this area are very dense compared to other countries, so YMMV.

13th Jun 2009, 02:12
I was wondering if a weapon that is using a laser diode for transmitting an electro magnetic pulse would be used for bringing down those aircraft we saw on tv? it works on the same principle or would as those new listening devices that use lasers to carry sound across a circuit into a speaker (or amplifier) but i was researching it and the laser sends the sound into the speaker by reflecting the laser back to a phototransistor. the laser listening devices cost like thousands of dollars but in my research i found you can make a cheap laser listening device for twenty bucks, off of instructables but i think it was removed. the phototransistors would need a high tolerance for current though and so would the diodes. they make laser diode current controllers. i think someone needs to look into this in case they used them on the planes but i dont know if lasers can carry high currents used to make emps.

13th Jun 2009, 02:52
:uhoh: Get Bloody Awful to go on strike about the quantity of butter in the sandwiches.

Take their hats away and see how they scream (cargo drivers who wear hats are considered ponces - hairdresser car drivers if that ain't clear enuff :hmm: )

13th Jun 2009, 03:13
Right, never mind bringing down airliners, that would be very anti-social and I have no desire to do any such thing.

However, I would quite like some sort of device which, when discretely fitted in my motor vehicle, is able to disrupt / distort / fry the speed radar used by my local constabulary. If it also disrupts his radio, comms, cellphone, engine computer, digital watch, and/or pacemaker, then these are bonuses.

Is such a device possible?

13th Jun 2009, 03:37
i think its possible. The United States has a new device that jams the IEDs from disrupting but im not sure how. Other than a conventional emp i dont know, i guess im not thinking enough, but i dont make them or anything. I cant. According to my laws. And if i did id have to go through the United States government to do so. Thats why i cant try to make OUR VERY OWN SATELLITE LASER EMITTING EMP!!! YAY! score one for the US when it comes to taking down missile silos... or disabling them in mid air. Unless... well.... Well... we do have the star wars system.. (a joke if you get it... cause it didnt knock one down). .Sorry about all that im just a schizoid that has too much time on his hands.

13th Jun 2009, 04:14
Is such a device possible?

Yes, but the size of the power source would be large, and it may do all those "niceties" to you and your car too:E

13th Jun 2009, 04:38
Hey i was thinking the same thing when i saw her ask that, originally. i dont know which thing the power source would be though. and uh... we arent talking the end of light here are we? that emerald tablet says more than just positive attraction. J/k about all this.

13th Jun 2009, 05:01
i was thinking though, if something were to explode to cause a one time use thing as though a invisible or visible flash, and would like a laser emp concept i had using a capacitor, i was thinking would it work? i thought of the explosions over NC VA and MD the other weeks ago. And you say it would do the same thing to the car? I wouldnt want to waste a nice car if i were you guys. i dont even want to waste a radio.

Loose rivets
13th Jun 2009, 06:37
I'm not able to calculate the energies involved, but it was well known, and witnessed by me several time, that a radiation SW of Newcastle would send the oil gauges of a Shorts, to full scale deflection.

One one occasion, the left one went to Mechanical Zero, while the right one went to FSD. These were almost certainly hard-wired, moving-coil, instruments.

I wondered if the energy involved may have been Ultra Low Frequency, and just affecting the delicate coil springs. Whatever, it was repeatable over many months.

This level of energy at a mile high is astonishing, and I've always wondered just what caused it.

13th Jun 2009, 09:41

In reply to a previous post of yours you quoted 26nf in reference to energy stored.Surely you mean 26 farads.

Google SUPER CAPACITORS, Interesting info on the development of high storage capacitors.With Supercaps it may be possible to aquire the energy needed for a small EMP device.

13th Jun 2009, 22:59
I don't get why folks are talking about [email protected] at all. They are only a problem when shone at pilots, they don't do anything to materials unless they are very powerful e.g. the CO2 [email protected] mentioned earlier.

My candidate for such a device would still be some kind of pulsed MASER - working in the Microwave range, not the Optical range of a [email protected] This has the potential to disrupt electronics directly, passing through e.g. metal cases or sparking off them. (Think about a metal fork in a microwave oven.) Like a [email protected], it's a coherent, directional beam, not an indiscriminate EMP blast that takes out everything in the area.

Pulsed, because you want a high amplitude microwave pulse, but it doesn't have to be continuous, which reduces the power supply requirements. (Like a microwave TASER - low "duty cycle"!) If the aim is to fry silicon circuit components, it doesn't take much actual power once you're past any casing. (You can fry CMOS components such as RAM, just by handling them without precautions against static electricity: it only takes a short sharp shock of static.)

If anyone builds something like this, please let me know, so I can set the police on you before you try it! :=

14th Jun 2009, 09:52

No 26nF.

3300 amps for 40ns is132 microjoules.

The capacitor is at 1000 volts and is allowed to lose 10% (100 volts) of that.

So E = 0.5CV*2

So CVsquared = 264 microjoules

V squared equals 10,000 (a 100 volt drop)

so C equals 264 times 10 to the minus 10 = 26.4 times 10 to the minus 9 farads = 26nF.

The 30 milliohms resistance makes this a bit difficult.

14th Jun 2009, 11:55
In response to BW - yes, you can. I wouldn't recommend the antisocial version, but you could (relatively) easily produce a radar transponder that would "reply" to the Police revenue device in such a way that your speed is shown at whatever value you choose.

One option is 30mph. The preferred option (this has been done - cough) is 550 mph.

There are only two snags with this:
1. You have to design and build it. Not many expert manufacturers would do it for you, although a "cottage industry" is possible.
2. Technically, you need a licence for it (as a radio transmitting device). It's not very likely the authorities would grant you one.

The next "snagette" is that the Police devices operate on a variety of frequency bands, and you'd have to cope with all of those, and then that some of their devices are laser-based, and that's a different issue.

15th Jun 2009, 11:30
I am told by people who have been involved that a challenge on the basis of traceable calibration generally has a good chance of succeeding. Personally, I try to keep to speeds where the problem doesn't arise