Jamming Aircraft Navigation Near Nuclear Power Plants

The German government want to jam aircraft navigation equipment near nuclear power plants.

This certainly could help if terrorists want to fly an airplane into a nuclear power plant, but it feels like a movie-plot threat to me. On the other hand, this could make things significantly worse if an airplane flies near the nuclear power plant by accident. My guess is that the latter happens far more often than the former.

Posted on September 29, 2005 at 6:40 AM43 Comments


kamagurka September 29, 2005 7:04 AM

Have you been reading up more on us Germans, or is our government getting kookier (Although I always knew Beckstein was a nut)?

Michael Ash September 29, 2005 7:13 AM

How big of an area are they planning to block? Nuclear power plants are highly recognizable landmarks. Any half-awake terrorist could easily find the plane’s position while it was still outside the magical electronic shield, check a map, and get a bearing to the plant. Unless they’re going to be extending the shield over hundreds of miles, which would be completely impractical, it would be trivial to get to the plant simply by pointing the plane in the right direction and waiting until they can see it out the window.

Perhaps the measures are meant for unpiloted aircraft, but the article talks about “visual distance”, which such a device would not care about.

The article is confused in general. It talks about “embarrassing incidents” involving light planes. But the only real threat that a light plane poses in a deliberate crash is to the health and safety of the pilot and passengers. In order to kill somebody with one, it’s pretty much required to actually hit that person directly with the plane. Crashing one into an office building will do no damage of consequence. Crashing one into a nuclear power plant would merely make one eligible for that year’s Darwin Awards.

Thomas September 29, 2005 7:17 AM

Well, it is estimated that nowhere in Germany GPS will work anymore because the nuclear power plants are so close together and for a sufficient security the radius of such system must be at least 100 km.

Did you read about the additional security measures, too? It is also planed to hide the nuclear power plant into fog to prevent them of being targeted “by hand”.

Did you even read about a German fairy-tale town called “Schilda”. In this town people always have such crued ideas 😉

Best regards from good old Germany

David Harmon September 29, 2005 7:21 AM

So, first they jam the navigation of nearby aircraft, then anything that gets closer is considered a probable terrorist?

“Never mind the Prime Directive, find me something I can kill!”

Steve Harmon September 29, 2005 7:27 AM

This is an incredibly stupid idea. Remember 9/11? It was the clearest, sunniest day in months here on the East Coast. I knew the second I looked outside that nobody “accidently” flew into the WTC.

The hijackers did not depend upon navigation equipment of any kind to find the WTC. As a matter of fact, they probably depended upon nothing more sophisticated than the Hudson River to find NYC.

Jamming GPS in random, unpredictable places (to pilots) will just make aviation less safe. Are the people who live near the nuke plant near the airport more or less safe when I suddenly lose my primary navigation display on approach in the clouds?

…and this drum has been beaten before, but nobody seems to be listening. A general aviation aircraft weighs less than a Honda Civic, carries about 40 gallons of fuel, and has limited cargo capacity. Heck – in a Cessna 152, I can’t fly with another big guy and full fuel; the plane doesn’t have the cargo capacity.

Small planes are not the threat people think they are. On a clear day, GPS is not necessary for navigation – ask an old DC3 pilot! This is a bad idea.

Lothar September 29, 2005 7:38 AM

I think the only part of the plan that might make sense is to hide the power plant in a gigantic could of smoke in case of a direct attack. This would effectively prevent visually targeted attacks. On the other hand, this system would have to be activated beforehand, so it would not help against surprise attacks.

Peter H September 29, 2005 8:12 AM

Don’t nuclear power plants have reactor containment buildings designed to withstand this kind of stuff anyway? It seems that a mere aircraft, no matter how large, will have trouble breeching the containment building (which apparently is the concern, since why provide this jamming for only nuclear plants). You would need some sort of “bunker-buster” bomb to knock a hole in the wall (or roof). If you’re facing an adversary with one of those and the means to deliver it, then some piddly navigational jammer isn’t going to help you.

Besides which, every nuclear plant I’ve seen (admittedly not that many, and all in the US) surrounds the containment building with cooling towers, transmission lines and towers, and a host of other obstacles that would make it difficult for anything beyond a small aircraft to reach the containment building sufficiently intact to do damage to it in the first place.

Seems silly to me.

Axel September 29, 2005 8:17 AM

For starters they would have “shrouded” the power plants in fog or smoke. Go figure. Guess not only the US government is reading too much Clancy. Or watching too many bad Hollywood flicks.

Kevin September 29, 2005 8:26 AM

Even if the movie-plot threat were credible, responding to it by
“jamming” air navigation systems is entirely infeasible.

Aircraft depend on several redundant navigation systems. First
among them is old-fashioned dead reckoning: The most important
navigational instruments are the airspeed indicator, the magnetic
compass or directional gyro, and the clock. One certainly hopes that
even German politicians don’t believe that these are subject to
bureaucratic intervention!

Next up in the hierarchy of sophistication is the venerable
Automatic Direction Finder (ADF). This system uses a directional
antenna (or a pair of differential loops) aboard the aircraft to
determine the direction to a beacon on the ground. It is based solely
on signal strength, and can home in on a broad range of frequencies in
the LF and MF regions, including AM broadcast stations. I am certain
that German AM broadcasters would not appreciate being told that their
signals will be unusable in the vicinity of nuclear power plants,
particularly considering the fact that a jammer’s signal would be
audible (and annoying to listeners) far beyond the range where it
would compromise direction-finding effectively.

The workhorse system is the VHF Omnidirectional Range
(VOR). Conceptually, it works by having one antenna pointing due north
that emits a pulse of radio waves in all directions once a second,
while a second antenna rotates once a second emitting a narrow beam of
radio waves. The signals are synchronized so that the omnidirectional
pulse is emitted when the directional antenna is pointed magnetic
north. (The actual beam is usually synthesized by an antenna array,
rather than by a rotating antenna, and the signal structure is
considerably more complex, but that’s the principle it works on.) A
receiver aboard the aircraft measures the time difference between the
two pulses and converts that to a direction to the fixed station. VOR
works on frequencies in the range 118-136 MHz. It is hypothetically
feasible to jam it by transmitting a stronger signal than that of the
fixed station, and giving a false direction. Since VOR is usable over
a wide area, the jammer would have to emit a large number of false
signals. To jam reliably, these false signals would be detectable (and
compromise navigation) over a much wider area than the immediate
vicinity of a power plant. Moreover, the jammer would compromise
aeronautical communications – which use AM on the very same VHF
frequencies; in fact, VOR’s support voice communications as well –
over an even wider area.

Most VOR’s nowadays are augmented with Distance Measuring Equpment
(DME; a similar military system often collocated is called TACAN for
TACtical Air Navigation, and stations with both are called VORTACs).
This system is a straight speed-of-light ranging technique that gives
the distance to the station by having the aircraft send out a UHF
radio pulse to a ground-based repeater and measure the amount of time
before the repeated signal arrives back at the aircraft. It would be
possible to jam DME without comprimising communications or commercial
radio, but it would not be terribly effective. DME is mostly a
convenience feature. It relieves the pilot of a small amount of
workload on an instrument arrival by allowing a single instrument to
tell the appropriate points for altitude stepdown. For wide-area
navigation, it can easily be dispensed with; a second VOR receiver
monitoring a station at some distance to one side of the aircraft’s
intended course can provide the same information in a less convenient
form. Only a handful of approaches actually require DME.

The sexy new systems are the Global Positioning System (GPS) and the
similar systems deployed by the former Soviet countries (Glonass) and
the EU (Galileo). These appear from the article to be the systems
that the German authorities are targeting. These systems are
satellite-based and work on time-difference-of-arrival of signals from
four spacecraft. The time differences are calculated by synchronizing
the spreading functions in a direct sequence spread-spectrum receiver.
This is a technique that is remarkably resistant to narrow-band
jamming or broadband noise. Effective interference with it would
probably involve spoofing a satellite signal. I suppose this might be
possible, although it would compromise GPS over a much wider area than
the immediate vicinity of a power plant. Even without GPS, however,
all the old reliable systems are still there and functioning. The
chief utility of GPS in air navigation is that it (augmented with
Differential GPS [DGPS]) allows for precision approaches into airports
that are not equipped with instrument-landing systems.

For the purposes of this discussion, I ignore some of the other
systems such as the Instrument Landing System (ILS), the Microwave
Landing System (MLS) and the obsolete A/N ranges. ILS and MLS are
useful only in the immediate vicinity of airports, and are used for
the sole purpose of making precision approaches to the runways. They
typically hae weak signals that can’t be used very far from the
airport, and they are set up to give very specific information
(lateral deviation from runway centerline, vertical deviation from
glide slope, and the time at which the aircraft passes three specific
distances from the runway threshold).

The article is rather confused about whether the threat is a piloted
or unpiloted aircraft. If the former, a power plant is a big target,
and a hardened one. I can see a pilot crashing into a containment
building, leaving a lot of aircraft parts strewn about the building
and little if any damage to the building itself. About the worst
damage that I could see is economic, if a suicide pilot were to
intentionally foul high-voltage transmission lines or damage
switchyard equipment (transformers, switches and capacitor banks).
An unpiloted missile is a more credible threat, although it would take
quite a large one – probably at least a tac nuke to breach reactor
containment. And if terrorists have access to SRBMs or cruise
missiles armed with tac nukes, the Germans have much worse problems
than point defense of nuclear reactors!

Sorry, I can’t even find a movie plot where this idea works.

Axel September 29, 2005 8:44 AM

The point is that to effectively jam the GPS signal without revealing the position of the plant would make navigation systems and GPS receivers unusable in a range of around 100 km around the power plant. Movie-plot, just like using high power lasers aboard commercial airplanes to counter missile attacks.

Unixronin September 29, 2005 9:10 AM

I can’t add any details or arguments that haven’t already been better discussed here. Just … this HAS to rank among the more idiotic ideas I have ever heard.

Mike September 29, 2005 9:28 AM

If they don’t want people flying over the nuclear sites can’t they use good old fashioned barrage balloons?

I suppose small aircraft may be able to fly around them but it’s the big aircraft that they are presumably worried about?

Of course they are highly visible and make it look like you’re fighting a war, but then they keep telling us that we are fighting a war.

Chris September 29, 2005 9:53 AM

As many have pointed out, the containment vessel on a modern nuclear power plant is likely to shrug off an impact from a light aircraft or even commercial jet airliner. There are, however, other tempting targets around the containment vessel. There are transmission lines that could be fouled to disrupt power transmission, the control facilities or pumping equipment could be damaged or destroyed. Further, many power plants store their spent fuel rods in pools outside the containment vessel in buildings that are little more than tin-roofed shacks. A direct hit to one of these shacks could disperse spent fuel and cause fear far in excess of any danger.

Personally I think the likelihood of an amateur/novice pilot navigating the local obstructions and impacting the storage shack is minute, but since we’re talkin’ ’bout nukular mahteriahls I better run for my life!

Mike Akers September 29, 2005 10:01 AM

This sounds pretty silly to me… any pilot should be able to find a nuclear power plant by dead reconing alone. Jamming Navaids is likely to cause more problems than good. Also, arent all nuclear powerplants (atleast the ones here in the USA) designed to withstand a plane crash without losing containment?

Ben September 29, 2005 10:05 AM

The airport in Harrisburg, Pennsylvania (MDT) is very close (about 3 miles line-of-sight) to Three Mile Island. You can easily see TMI depending on the angle of approach, so I don’t think that this would be a good thing to try and implement in the US. I’d have to imagine that there are other airport/nuclear power plant combinations within similar proximity.

Any comitted evildoer will research the location of the facility beforehand and will use visual clues for navigation. This won’t protect anyone.

Most of the nuclear power plants in the US have reactor buildings designed to withstand a crash from a commercial jet liner from the era in which they were built. From my understanding, nobody really knows what would happen if a jumbo jet was to crash into one of the buildings at full speed.

Dima September 29, 2005 10:33 AM

Jamming GPS won’t make things significantly worse for pilots – if a plane is somewhere by accident, it’s not like its pilots have been using GPS to get there anyway. And GPS-jamming exercises are a regular occurrence here in the vicinity of Washington, DC, (and they are properly NOTAMed), and I don’t remember any reports that it caused any problems for pilots. Jamming GPS might perhaps help against JDAM-like munition (rumors are it happend more than once during the war on Iraq), and even though GPS systems are pretty cheap nowadays, I strongly doubt using one beats a piloted hijacked jet at cruising speed.

Schilda Curious September 29, 2005 10:50 AM


I found a link about Schilda/Gothamites, but it’s kind of short (and in German, but the google translation is acceptable but hard to get through).


The way you mention it seems to imply that there is a large series of these (this site has 8; maybe that’s complete?). You got a link or a pointer to a collection (preferablly in English)? Maybe a book that could be purchased? I could find nothing definite.

It’s interesting that the lessions that childhood tales are meant to impart are ignored in adulthood. I’m sure there is some thesis waiting to be written here — with the current political climate as the case study.

jammit September 29, 2005 11:18 AM

Let me get this straight. To prevent planes from crashing into nuclear power plants he plans on scrambling navigational aids around nuclear power plants. This joke writes its self.

Barney September 29, 2005 11:23 AM

@Bruce Schneier –

You often diss “movie-plot threats”. But wasn’t 9-11 just such a threat?

Jamming GPS may be stupid, but in general, is it a good idea to protect nuclear power plants?

Ben Klausner September 29, 2005 12:00 PM

What these people (and everyone in Hollywood) don’t seem to understand is that jamming is not some magical wrapper that goes around a radio receiver. It is a high power transmission that competes with the signal to be jammed, creating so much noise that the original signal is unusable.

In this case, if they are going to put jammers at the power plant sites, they might as well put homing beacons, because any tech-savvy terrorist will just navigate to the stronger, local radio source.

Ian Mason September 29, 2005 12:02 PM

The other day on British television, a British satirical comedian read out a list of lethal events more or equally probable than being killed in a terrorist attack. Having a plane fall out of the sky and kill you was at the same probability as a fatal terrorist attack. I guess the Germans are just trying to make it less probable that you’ll get killed by terrorists than by a plane crash.

Tom Distler September 29, 2005 12:24 PM


Consider the entire set of possible disasterous terrorists plots. How big do you think that set is? Based simple on the shear number of fiction books exploring these plots (not to mention all of the permutations on those plots), the set becomes quite large.

In fact, the set becomes so large that it is unresonable to try to protect yourself from each element in the set.

A totally different strategy needs to be taken: you need to focus on catching the people who will carry out the attacks. This is best done through old-fashion police work.

An important distinction needs to be made between 9-11 and “movie-plot threats”… 9-11 was an actual event. It’s like trying to compare someone who actually won the lottery to everybody else’s experience of playing.

nuclear September 29, 2005 12:32 PM

I agree that the whole idea of jamming navigation is silly.

I am curious though…There have been a number of comments about the “unbreachable” containment buildings being able to withstand an aircraft crash.

Wheren’t the WTC towers also designed to withstand an aircraft crashing into them? The problem being, the buidling designers only assumed an accidental (relatively slow speed) crash of a 1970’s airliner. They didn’t anticipate the size and fuel load of aircraft 30 years into the future. Also, that the aircraft would be flying at a high rate of speed.

I have to wonder what assumptions have been made with nuclear reactor containment buildings regard aircraft crashing into them? Maybe this is more movie-plot, but could they withstand a fully fueled 767 cargo plane loaded with a few thousand pounds of high explosives coming in at a high rate of speed? It doesn’t seem like it would be that difficult to commandeer a FedEx plane, and also to coordinate shipment (that would end up on the same plane) of a number of mixed sized packages each containing some amount of high explosives, added together, achieving significant “bunker busting” capability.

u235 September 29, 2005 2:03 PM

I always thought Bradwell (now closed) had a weakness here with the six primary circuit top ducts (for each reactor) exposed above the roof. Burst ducts are catered for in safety assessments, but IIRC (could be wrong) only to three out of six at a time.


Some (all?) of the white containers will have CO2 – a danger to those on site if released.

d September 29, 2005 2:06 PM

From the article:

The move follows an embarrassing incident earlier this summer when an emotionally distraught man committed suicide by crashing his light plane within metres of the Bundestag parliament building.<<<

This is an embarassment prevention measure, not a security/safety measure.

Michael Ash September 29, 2005 5:01 PM


9/11 was in no way a movie-plot attack. Aside from the attempt by an Algerian group to crash an airplane into the Eiffel Tower in the early 1990s, there is also a history of literally hundreds of people crashing airplanes into things in order to destroy them, during the closing phases of the Pacific campaign of World War II. Just because nobody in charge saw things coming, and just because it was a civilian attack, doesn’t push it into the realm of the movie plot.

Tethered Rose September 29, 2005 5:05 PM

@ Michael

“Just because nobody in charge saw things coming, and just because it was a civilian attack, doesn’t push it into the realm of the movie plot.”

Right. No one in charge saw it coming. Those of us who saw something coming, weren’t being listened to, either!

Movie plots are usually (big emphasis on usually) intended to bring something to light that may occur, has occured, or in the right combination, may occur again. Good, bad, or indifferent.

Stay focused on the problems and we’ll be able to solve this whole thing swiftly, and easily, folks.

Anyone ever had a kidney stone? Pass it like a kidnety stone and let’s move on.

Ari Heikkinen September 29, 2005 6:04 PM

I’d be more worried if some plane would fly near a nuclear plant by accident and getting its navigation systems hosed. Jammers in place “just in case” is about as idiotic as it could possibly get.

Thomas Sprinkmeier September 29, 2005 6:30 PM

My wife figured out what this is about.

It’s not “movie plot” security, but “book plot security”:

Hogwarts is unplottable, we jam GPS (*). We need to work on the global backup navigation field (aka “earth’s magnetic field”) next (see “Diamond as big as the Ritz” for details).

Next step is to camuflage it. How hard can it be to camuflage huge structures in a know location belching steam near a body of water with high-tension power-lines leading to them?

The ultimate step is to add SMS and WiFi transmitters that send urgent appointments to anyone nearing the site. Get too close and your PDA will beep, reminding you of an urgent appointment somewhere far away!

(*) I believe the AMRAAM has a “home-on-jam”
mode to defeat enemy jammers. Could a similar tactic be used to home in on the GPS jammers?
Anyway, just get a local hippy, tell him you’re planning to drop leaflets over the plant as a publicity stunt and he’ll be more than happy to help you navigate your Cesna!

Dylan September 29, 2005 7:05 PM

All these events are detectable after the event. If they were detectable before the event, they wouldn’t happen. Detectable incidents are prevented (actively and passively) all the time.

As long as there are no more plane incidents, the TSA can do anything and claim that they are being 100% effective. All the terror organisations need to do is nothing at all. They have created a self-sustaining reaction in authorities, which will eventually lead to the disintegration of those authorities. If the reaction seems to be dropping off the boil, they only need to prod a bit to start it up again.

I believe that all we need to do to combat terrorism is all ride bicycles. Work it any way you like.

Logi September 29, 2005 11:21 PM

I flew over France last week on a clear day and at one point between naps I could see three columns of steam which I decided were from nuke plants. I’m pretty sure those columns reached several hundred metres into the air, I might well believe a thosand, before they seemed to hit a denser layer and spread out. No man-made bank of fog is going to hide that.

Axel September 30, 2005 1:31 AM

@Peter H: that’s the point. Several older power plants should be phased out because they would not withstand a direct hit from a jet airplane. So in light of that the power plant company is rather interested in these movie-plot thingies.

Thomas September 30, 2005 3:28 AM

Hi Schilda Curious!

Googleing around I only found information about Schild and the Schildbürger in german language. Even a book called “Die Schildbürger” (available at Amazon.de). But I didn’t find an english link.
But as far as I Understood from Wikipedia.de there is a similar fairy-tale tale town called Gotham (“Wise Men of Gotham”) that you mentioned too.

VWM October 2, 2005 4:22 PM

Well, there seems to be a theoretic chance to make things nasty with 5 of the older German power plants. That is what the “Federal Office for Radiation Protection??? [1] found out.

A crashing plane will probably not brake the reactor containment building but burning fuel might block ventilation shafts, and sabotage the cooling of the reactor. At least this is what a power plant lobbyist told me.

But, the distance that can be fogged or jammed will be passed by a plane within the last few seconds unless thy want to jam half of the country, thereby destroy the brand new Toll-Collect [1] system.

Heise [3] is suggesting to use a fly-by-wire System instead, which automatically turns an approaching plane from predefined coordinates. I don’t know if that will work, but it sounds good because that could not only protect the nuclear plants but a lot of other possible targets.

see also
[1] http://www.bfs.de
[2] http://www.toll-collect.de
[3] http://www.heise.de/newsticker/meldung/64016

Steve October 4, 2005 10:07 AM

I lived in Germany (south of Mannheim on the Rhine) during and after 9/11. I was accutely aware of the nuclear powerplant in my back yard. The concept of crashing a plan into the powerplant was very real and very scary. I’m not sure if the large amount of US military plans flying over were for training or protection… However, I don’t think there is any real protection bubble that can be applied here.

TiL October 6, 2005 6:42 AM

As VWM pointed out, this plans would not only cost the German government a lot of money, but it would also make them lose a lot. The newly introduced motorway toll is gps based and and a part of the German national budget relies on it. Have a look at this map http://www.energieverbraucher.de/ew_images/strombezug/energie-akws.jpg
. You´ll see that if you jam gps signals in a said secure radius of 100km, parts of northern and western Germany will have no gps signal at all, as the nuklear plants are quite close to each other. As you want to protect Germany, you should also think of it in the context of its neighbors. There are quite a few French nuclear power plants along the rhine, as well as Swiss and also Czech npp´s along the border. To protect the German population, you should jam their position as well. Now think of the single plant ‘Biblis’. It is located near of Frankfurt. By jamming it in a radius of only 70km, you´ll be jamming the whole conurbation of Frankfurt, the biggest European airport in Frankfurt and render the motorways near this area as well as to Mannheim, Mainz, Wiesbaden, Ludwigshafen, Heidelberg and some others completely unusable as far as gps navigation and the toll collect(r) system are concerned.
Now, you should also think about the fact, that disturbing radio signals in Germany is subject to the Strafgesetzbuch (criminal code), and there is no exception for the government in it.
Now finally think about the other plan, the one with a real lot of smoke dischargers involved. A nuclear power plant is, as some others already pointed out, quite a visible landmark. It is the hell of a problem, if you destroy the cooling facilities or the reactor core shielding. It is even a problem, if you only disturb its function. A plane the size of a 747 could certainly do this with its fuel tanks still full. But I´m losing track. What I wanted to say is: If you use smoke dischargers to render a big landmark invisible, you only only create a bigger, more visible landmark. I guess , if you crash a plan 500m in front of of a plant, you´ll hit the plant due to the planes inertia. Now imagine a cube of 500x500x500m. It is made of fog/smoke. 1. How do you want to produce this lot of smoke in about 3-5min (depending on the speed of the approaching plane and when you detect it). 2. As 500m^3 are not enough, now think of the problem of 1000m. 1000m^3.

But I´m sure the German government will have worked this out as well and find a solution. As soon as they were able to form a government after those elections…

Carla Hein October 7, 2005 1:48 PM

The US. Department of Energy is stonewalling research on fusion/fission high-temperature, full-spectrum lasers. Thermonuclear heat at the visible light center of the spectrum does NOT emit gamma rays. Private industry research groups who will study F/F lasers welcome

Obermenzing December 6, 2005 9:37 AM

Any reactor site has piping, tools, communication equipment, computers, support equipment, drainage etc etc all in weak buildings.
A 747 crashing into a nuclear site would cause MAJOR problems, even if the main containment survived. Key people, key records, key software, key monitoring systems could all be lost. I doubt that a reactor hit in this way would ever startup again.

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