back to article Royal Navy halts Highlands GPS jamming

Following complaints from local fishermen, the Royal Navy has suspended satnav signal jamming during its ongoing Joint Warrior naval exercises, despite making every attempt to let people know. Locals around the Western Isles say the jamming of GPS has disrupted their lives, and put the safety (and profitability) of fishermen …


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  1. jonathanb Silver badge

    When they send out a distress signal, they presumably give the GPS co-ordinates of where they are located to help the coastguard reach them more easily, and they won't be able to do that if GPS is jammed.

    1. Anonymous Coward
      Anonymous Coward

      Whilst you are technically correct, you are also quite a way away from the point. They can get your rough position through VHF, but they wont need to do that because you will know roughly where you are anyway (as all good skippers do). They will scramble the rescue craft and you will see it, you then fire your flares and bobs your granddad's son they find you, no GPS needed.

      If you are in a position where a transponder needs to hit the water to activate and give off its GPS coords (think sinking or capsize where there isn't much chance of using the radio), then you are already fucked and by the time help gets to you the north sea will have made you an icecube.

      1. Miek

        M'aide M'aide, I have just come round after suffering a blow to the back of the head from a swinging Boom, I must have been drifting for hours and my GPS is not working. Oh and there's loads of blood coming out of the back of my head, can you find Wally?

        1. Matt Bryant Silver badge

          RE: Miek

          Well, in that case you're in luck, 'cos the RN are running an exercise in the area, massively increasing your chances of being found, especially as they can triangulate your radio transmission very easily. Of course, if you were a mildly competent sailor then you'd just take a look at your chart, guesstimate drift over the period you think you were unconcious, and have a good enough idea of where you were likely to be in order to decide a rough course to steer for the mainland. Once you get close to the shore you'd be able to identify landmarks and find a safe harbour.

        2. nyelvmark

          M'aide M'aide

          Well, if you're such good friends with the coastguard that you can address them in the intimate voice, then they're probably already looking for you, non?

      2. Stu_The_Jock

        North Sea ?

        I think you'll find the North Sea is off the EAST coast of Scotland, and round most of the Western Isles is the ATLANTIC OCEAN . . . So if you're off the Western Isle and request a coastguard rescue to the North Sea, you are well and truly screwed . . .

      3. ToFoBr

        A DSC radio will keep transmitting a MayDay including the position once the button is pushed even if the crew are incapacitated.


    2. PolarPerson

      GPS and Distress calls

      Although distress calls are (of course) transmitted in a vastly different part of the EM spectrum from GPS, disabling GPS disables a crucial part of the Global distress system (GMDSS). A VHF technology called DSC provides the capability to broadcast digital message containing latitude and longitude; these are used heavily in distress messages that are provided on pushing a Big Red Button. Of course, the latitude and longitude are normally provided by a GPS system; other types of electronic position finding are rarely used.

      Automated distress beacons also provide positions from GPS; again, although the communications technology is not compromised, the GPS is. In this case, there is no alternative technology feasible.

      However, the other side of the coin is that I, an amateur yachtsman who happens not to have gone to sea for a couple of months, knew all about these tests. I really don't understand why the fishermen didn't know about them - they are routinely notified through a wide variety of channels. What do the fishermen want? Personal visits from HRH?

  2. John70

    Boats and GPS

    Are they saying that if the GPS malfunctions on their boat they are screwed?

    Maybe they need to dust off their compass and do it the old fashion way.

    Good practise for them in case of such event.

    1. TonyG

      Not quite.

      Most fishermen can still navigate without GPS but in a similar way to how most people don't use a map in a car, most fishermen don't use charts now (but still have them onboard in case of failure).

      GPS is used for net fishing close to the coast where the accuracy allows the boat to go closer to shore than you'd attempt without GPS.

      From what I've heard - there's been outright GPS failure which means you just don't fish there and go for deep water fishing or back to port.

      The real problem seems to be cases where the GPS is reporting inaccurate positions so you think you're safe and end up hitting rocks or catching nets - both of which appear to have happened during this exercise.

      1. Daniel 4

        "Most fishermen can still navigate without GPS but in a similar way to how most people don't use a map in a car, most fishermen don't use charts now (but still have them onboard in case of failure)."

        I use a map. Less talking back to me than a silly GPS. ;)

        "The real problem seems to be cases where the GPS is reporting inaccurate positions so you think you're safe and end up hitting rocks or catching nets - both of which appear to have happened during this exercise."

        GPS is, first and foremost, a military system - civilian GPS was always a very nice afterthought. If the RN needs to jam it for practice twice a year, so long as they send out proper notice, the fisherman should simply cope. As for said notice, it's already been noted on this forum that amateurs who sail in that area were well aware of the coming failure - if the fisherman weren't paying attention to what should be standard notices, then that's their own fault. What are they going to complain about next, that the RN isn't nuking storms out of the sky so they keep fishing?


        1. TonyG

          @Daniel 4

          As you say, as long as they send out the proper notices.

          I live over 35 miles away from where the jamming was taking place (well outside of the range that the MoD specified as being affected by the jamming) and my GPS was giving positions about 10-15 meters from true.

          So the notices that were issued were inaccurate to say the least.

    2. This post has been deleted by its author

      1. Fred 24

        Already done!

        Android Market... IamAt

      2. Mike Banahan

        Sextants etc.

        I think you might find something along those lines - using a digital camera as an emergency sextant - in The Lo Tech Navigator by Crowley combined with the excellent Emergency Navigation by Burch.

        Problem is, a single sextant reading can only give you a line of position (long line drawn across your chart) and not a fix where two lines cross. Admittedly, if you can do that then it helps anyone searching you a lot as they only have to look up and down a line instead of hundreds of square miles of sea.

        I was thinking of doing an solar navigation app for my Android, but hadn't thought of trying to combine it with the camera ...

        1. This post has been deleted by its author

    3. big_D Silver badge

      When I were a lad...

      When I did my cert for offshore sailing, we were taught to use charts, tide tables, sextant etc. and one should never rely on the GPS, you would use it to check drift etc. between readings, but you only a fool would rely on the GPS, without plotting their actual course on the map.

      I guess times are changing...

      I gave up using GPS, when my system messed up and had me driving through the middle of Lake Constance, after I had been driving north for 2 hours from Munich! :-D

      I still use Post-It notes when travelling somewhere, they are a lot more reliable and don't tend to go blank if the power fails :-P

  3. SkippyBing

    I'd suggest if your a commercial fisherman an ability to navigate without relying on GPS might be a good idea, in fact I'd be surprised if it wasn't a requirement of the license to drive a ship (when i got mine you weren't allowed to rely on GPS it was all visual and radar fixing).

    It's not as if they're in the middle of the Atlantic these are coastal waters with the world's supply of distinct headlands to identify your position with. They don't even particularly need GPS to give their position when in distress either, radio direction finding having been perfected in World War 2...

  4. Yet Another Anonymous coward Silver badge

    Emergency beacons have GPS

    The mandatory marine 406 Mhz emergency location beacons transmit their GPS coordinates to let rescuers know where you are - as do commercial systems like SPOT

    1. Ru

      They can also work with no GPS at all

      Initial location accuracy only to within a few kilometres though. GPS improves that to within a couple of hundred metres..

    2. Mike007 Bronze badge

      Although one would assume that should the coast guard receive a distress signal with no/an improbable GPS location, they, being fully aware of the activities going on, would be able to call up the RN (who they already cooperate closely with) and ask them to turn off the jamming for a bit so their GPS comes back up. This is assuming that the beacon doesn't also contain a homing signal.

      Also I expect that the RN would be monitoring emergency bands in areas they are operating in, and may well already have a rough direction from one or two of the high tech communications rooms onboard the various ships (depending which ones were involved in the exercise) and probably wouldn't even need the coast guard to call them before they respond.

  5. jake Silver badge

    The mind boggles ...

    I used Loran briefly, when I operated a commercial salmon boat out of Noyo Harbor back in the mid 1970s ... I soon went back to charts & dead reckoning. I've fiddled with GPS, on and off, but charts and a compass are really where it's at when it comes to open water.

    I spent some time living (and fishing) out of A' Chomraich when I was late teens/early twenties ... None of the fishermen I worked for even had a chart on board. One wonders how much of what makes us human that humans are going to lose thanks to so-called "convenience" ...

    1. Elbrop


      Using a boat eh? Back in my day I'd wade out and throw a net, as god, and our ancestors intended.

      And I lived in a cave, Natures own palace we called it. Well not exactly, we had none of that fancy language you kids have now. But we lived better for the lack!

      1. Tom Maddox Silver badge

        Re: Huh

        Oooh, a net! How fancy! Back when I was a lad, we would wade out and catch fish with our bare hands and then tear them open raw as the gods intended.

        My family roamed the open plains, counting on our bearskins for warmth. Ever tried skinning a bear with your bare hands and curing the skin without fire? It ain't easy!

    2. nyelvmark


      Don't worry - fishing boats powered by Java are coming. If you try to move your boat closer to the shore for better fishing, you will get an error message:

      "The function 'MoveCloserTo Shore()' is deprecated. Please use 'MoveFurtherFromShore()' "

      1. jake Silver badge

        I think the commentards ...

        ... have underlined my point for me.

        If you don't understand TheRealWorld[tm], you will make the same mistakes of generations before you ...

  6. Tony Humphreys

    How on earth did Cook, Columbus etc manage without GPS? I suppose fishing has only been possible since GPS became available?

    Fools - how on earth did we manage to last thousands of years.

    1. Richard 12 Silver badge

      To be fair, when Cook et al were sailing, a lot of them didn't come back

      These days we seem to expect something like five nines survival rate for mariners.

      I know that's completely unreasonable, and we should go back to the good old days when ships came back 80% of the time, often with more than half the crew still on board!

      1. Peter2 Silver badge

        And to be fair, the reason a lot of them didn't come back is because they were sailing a fragile ship the size of a modern trawler to the far side of the the world without the benefit of charts, because the land they were sailing to hadn't been charted *at all*, and hitting ground resulted in the ship falling apart. Add to that little things like scurvy etc. Unless i've missed something, none of those conditions are true for a modern trawler?

        Given any IT bods understanding of the importance of backups, I think it's going to be a struggle to persuade most of us that the navigator on a ship shouldn't need to know how to read a map. Most scouts can manage that at 15 at a level that will let them get by, and i'm pretty certain I could chart my own position reasonably accurately with a map and compass simply by calculating the speed and thus distance travelled along a compass heading from my last position.

        1. Richard 12 Silver badge

          Mostly true, Peter

          Hitting ground still causes ships to sink, steel not being naturally buoyant. While they fall apart less often, it's little solace to know that your submerged tomb is only in one or two pieces.

          GPS will give you a location with errors measured in metres or tens of metres.

          Taking a fix on known coastal features can give you a similar precision of fix, however it relies on good visibility (you need visibility of at least three coastal features) and tells you where you were a few minutes before.

          Dead reckoning relies on a reliable fix to start you off, and your precision rapidly drops off - hundreds of metres within hours, several km within a tide. Hence trying to take a fix hourly.

          - Dead reckoning on land is much easier because the land doesn't move under you at continually varying velocity.

          The ancient mariners would take a fix using sun, moon and stars, and were often off by hundreds of km. Astromical fixes are not very precise and you can only take them at specific times of day - really local noon and midnight. (Sunrise/set and rise/set of chosen astronomical bodies are possible but you need big lookup tables and to be completely out of sight of land in perfect visibility for them to be useful.).

          Off the coast of Scotland in autumn, how good do you think the visibility usually is to take those coastal fixes?

          The Royal Navy have inertial navigation equipment capable of dead reckoning with the accuracy of GPS, given a good enough fix to start with. Civilians, less so.

      2. JaitcH

        Cook et al were sailing, a lot of them didn't come back

        But those were the ships that sailed too close to the edge of the world, where old charts had pictures if evil looking men and giant fish that ate ships..

    2. BristolBachelor Gold badge

      Didn't Columbus arrive at the wrong continent? Wasn't he going to the East Indies? Perhaps GPS would've helped...

  7. TonyG

    Living on the isle of Lewis

    There's normally an article in the local rag letting people know that an exercise is on it's way - this time they seem to have forgotten.

    Normally the jamming isn't a problem as it shouldn't affect the Western Isles (as indicated in the map in your article) and fishermen just avoid the affected areas.

    As mentioned in your article, the real worry from the fishermen is that DSC has failed (and well outside the areas specified by NATO). Although DSC does use a different frequency than GPS it stopped working which is worrying as it allows the coastguard to pinpoint the location.

    On the island itself we've seen problems with GPS, mobiles (worse than usual), internet connectivity (due to a large percentage of the island using a wireless network) and satellite TV.

    In general, a bit of a non-event for people living on the island but worrying for the fishermen especially since there's no emergency tug in the area anymore.

    1. Anonymous Coward
      Anonymous Coward

      Think yourselves lucky...

      When I lived up there they had regular "Spetsnaz attack" exercises. That was back when the airport runway got used for significantly heavier stuff than now ;)

      While the idea of the RAF running all over the place "capturing" strategic sites such as petrol stations sounds amusing it is a monumental PITA when you live there.

      It'd be nice if the RN would fuck off down south and run their exercises - I mean apart from Holy Loch they are exclusively based on the south coast of England. What the hell are they doing up here if their tactical base is the south coast?

      People should note that the west coast of Scotland has LOTS of these poxy exercises (I'm sure Mr Page remembers where the sub captains qualified?) and that there is some irony/sarcasm above ;)

  8. James 47

    Will they do this Galileo?

    Can they? Also, there are some interesting documents about Galileo in the new Wikileaks archive, maybe an El Reg journo might like to take a look.

    1. Anonymous Coward
      Anonymous Coward


      The Americans insisted on being able to selectively jam Galileo and the necessary arrangements have apparently been made to facilitate this. However, it is planned to use EGNOS (an extension to Galileo) for aircraft navigation around Europe. One wonders if the military will be so cavalier about jamming systems that will be used to fly and land aircraft.

      1. peter_dtm
  9. Tascam Holiday

    As I understand it GPS is supposed to be treated as a secondary navigation aid for exactly this reason - the military reserves the right to degrade or switch it off at any time, anywhere.

    In practice mariners obviously aren't doing this, but perhaps they ought to dig out their sextants and Harrison chronometers and practice without GPS occasionally.

    1. Bob H


      The US Military made a commitment to the United Nations in respect to intentional disruption of GPS at source, they committed to never doing it because GPS had become critical to so much of our lives.

      As a side note:

      I suspect that mobile and internet communications have been disrupted because many of them using GPS to discipline their frequency sources. The high accuracy 1PPS pulse from GPS is used to synchronise microwave relays as well as some fibre nodes. Most data centres should try to have a clock/frequency source which can sustain itself for a while in-case GPS is unavailable, but eventually that might drift and I am not sure if mobile base stations / telecoms relays contain such an expensive/accurate time source.

      1. Peter Gathercole Silver badge

        Local time sources

        Generally if you buy a time appliance that provides a NTP stratum 1 source using GPS, MSF or DCF, then they put a high-precision temperature controlled clock in the appliance for just the situation where your exterior time source is not available.

        Normally these are accurate to <2ms per day drift (this is for the entry level device from Time and Frequency Solutions Ltd. - other NTP time appliances are available), so will take over a year to drift even a second from real time if they lose their external feed. There are better ones if you need more accuracy.

        So if you need accurate time, relying on a regular feed from GPS is just not necessary.

        Of course, some people might be doing time synchronisation on the cheap, but that is then their problem.

      2. BristolBachelor Gold badge

        @Bob H

        I'd be very interested in knowing when they did this. I know that in a recent skermish, the US put in a number of fixed markers with known Lat/Long and turned off the GPS in the whole regon for a while. The only way of knowing where you were was using one of our inertial navigation platforms, and syncing the location at one of the known points. If you ever switched it off, it was screwed though; it could find true north after about 5 minutes, but apart from that it wouldn't know where it was.

    2. JaitcH

      "supposed to be treated as a secondary navigation aid"

      This is a little disturbing as the new point-to-point flight system, as opposed to corridors, is predicated on using GPS because it is a single system, like the earlier Decca Navigator, as opposed to individual, multiple systems such as inertial or radar navigation.

  10. Anonymous Coward
    Anonymous Coward

    In future

    will these exercises jam GLONASS and Galileo?

    1. TonyG

      Since it seems to be jamming other satellite signals (such as TV) and mobile signals - I'd say yes.

    2. Ru

      Probably already does

      They're pretty close, channel wise, to GPS.

    3. Anonymous Coward
      Anonymous Coward

      Re: In future

      GLONASS is Russian, so jamming it is going to *really* upset some people who have the ability to make their feelings known.

      Galileo is a civilian system, so I'm sure that Brussels will not be happy if the military starts jamming it. Probably pass a Ero-lay making such jamming illegal!

      1. NickW1

        Remember that they are not jamming a system or systems, just rendering the signals unusable over a patch of the earth. GLONASS really can't complain if their system is inoperable over north west Scotland and Galileo likewise, unless it is so frequent or extensive that it starts putting off paying (or potential paying) customers.

      2. Elbrop

        No more than the US was upset by this. As in not at all. And why should it?

  11. Elmer Phud

    To the 'why not use a map' comments

    O.K., how about you having to revert to pagers for a bit?

    1. Anonymous Coward
      Anonymous Coward

      Yay for pagers

      Back in the early noughties, we watched in horrified fascination how some fellow students apparently had lost the ability to do anything at all without first calling a mate or two to discuss how to do it. Now kids would presumably tweet or post on facebook or text a question or two. It's quite amazing how quickly people start to believe they won't survive without certain high technology they've become accustomed to.

      Having a jolly old excercise trying to do exactly that, surviving without, say, GPS, or phone, or what-have-you, is instructive. Plenty of people should try, just to see where the weak spots in their thinking are. Knowing you're vulnerable and understanding the consequences is half the battle. This fisherman might have a point he's missed the announcement, but I would've thought he'd've picked it up from some marine data service or other. I mean, if you have GPS, why not that? IIRC there is at least one but not being a mariner I can't quite recall what it was called.

      As to pagers, such systems have a much wider range than cellular phone systems do, and personally I'd like control messages to be sent over such a system, obviating the need for mobes to always stay signed in to the nearest tower, which is inexplicably recorded and kept for years. The phone can sign in when it gets a page telling it a call is incoming. And SMSes don't even need a sign-in, the page would suffice. I think that's a good idea, yes.

      1. Andrew Woodvine

        I like your thinking in relation to control messages but in practice this would not work. Suppose your mobile is switched off/out of coverage for example, and an SMS was sent out via the pager system, then the recipient would never receive it.

        1. Anonymous Coward
          Anonymous Coward

          GSM off, SMS vanishes?

          SMSes already fail to get delivered if the phone remains switched off during the SMS its entire lifetime. Though I don't know what'll happen if the phone company decides to store "sent" messages for longer than that anyway. Probably not deliver but archive anyway. Anyhow. Pagers of course did have that problem but with lower power draw and simply repeating sending it once an hour or so for a day or two that was "good enough". With GSMs, well, maybe they can have a pager-like modus, just receiving pages without signing in to towers. And perhaps they could delay acknowledgement of received SMSes until next time they really have to sign in. Or(/and) just sign in once a day or so for a full status check. I don't see it as a big problem since paging systems typically have better reach anyway. The only thing that changes is that the network doesn't get instant gratification, er, acknowledgement, and since the messages are tiny compared what we know how to pump through the aether now-a-days, well, not really a problem.

    2. miknik

      A map and a chart are not the same

      GPS map in your car is great, no big deal if it packs up, plenty of signs etc and worst case scenario you can pull over. I would have no qualms using a GPS as my sole navigation aid on the road.

      However, taking to the sea/sky without a current chart is foolhardy. I've experienced GPS failure midflight, with no chart I wouldn't have known if I was near controlled airspace/danger areas and wouldn't have been able to find the frequencies of any beacons to obtain an accurate position fix. I'm not a mariner but can only assume nautical charts contain similar information.

      GPS is great when it works, but everyone managed before it and if someone can't cope without it then you wouldn't catch me on their ship/plane!

  12. Anonymous Coward
    Anonymous Coward

    What they all seem to have forgotten... that GPS is first and foremost a military system. And it's not even our system, it's the yanks. It's only courtesy that they inform everyone about it.

    As noted above - in mission-critical applcation, GPS should never be your primary navigation device.'s interesting the navy are conducting GPS-less maneuvers; obviously one of their anticipated attack vectors is complete destruction of the GPS network by their antagonist. And who has recent form with destroying satelites, I wonder...

  13. Graham Bartlett

    @Tony Humphreys

    Christopher Columbus was aiming for India but hit the Bahamas instead. Not the best example...

    1. Michael 36

      It's not that bad

      If he had named the Bahamas India instead of Bahamas nobody would have been any the wiser.

    2. PJI


      ry using a GPS navigator when you do not know the coordinates of the destination or the road diversion is not yet in your GPS's idea of the world; A map would at least show the lie of the land.

      I could be wrong; but he did not know where either place was, just worked on a theory of where it may be, plus being in a vessel with rather less refined methods of overcoming wind and tide and no charts, not even a school atlas, of any part of the route. T

      GPS is not always, or even often, as accurate as you seem to think. A couple of hundred metres out could be interesting in some parts of the sea.

      You know, liferafts and the like could well have a small engine; but for some reason, they tend to include some oars, just in case. Ocean yachtsman have very snazzy self-steering gear; but the ability to steer "by hand" is somehow seen as useful. Electricity in the home is wonderful. Oddly, most people have got a torch and even candles just in case it fails.

      Technology is useful, fun even. But humans have not changed, nor has the underlying physical world.

  14. Anonymous Coward
    Anonymous Coward

    @BOB H

    >Ref BOB H: The US Military made a commitment to the United Nations in respect to intentional

    >disruptionof GPS at source, they committed to never doing it because GPS had become critical to

    > so much of our lives.

    You obviously missed the publicly available FAQ document made available at the time when they disabled Selective Availability .... I quote ....

    "The directive also requires that the DoD develop measures to prevent the hostile use of GPS and its augmentations to ensure that the U.S. retains a military advantage without unduly disrupting or degrading civilian uses. The DoD has an active Navigation Warfare (Navwar) Program fulfilling these requirements. The decision to discontinue SA was supported by the commitment being made by the US in the development and deployment of capabilities to selectively deny civil radionavigation signals on a regional basis when our national security is threatened. This regional approach to preventing adversaries from using radionavigation services against us circumvents the need to degrade the civil GPS system globally through the SA technique."

    So they never said they would "never do it" .... they just said they would "never do it globally".

    1. NickW1

      And the reason they said they would never switch off GPS globally, and why they removed SA, was because they wanted to remove as many justifications for Galileo as possible.

  15. MattW

    No sailors on here then?

    Modern GMDSS radios take an input from a gps receiver and will initiate a geo located automatic distress call when a 'big red button' on the radio is pressed (say when the skipper has his hands a bit full trying to control his craft / not sink etc).

    So gps disruption may effectively disrupt emergency calls.

    1. peter_dtm

      obviously not

      any 'skipper' claiming such a title (instead of 'suicide pact leader') would know roughly where he was at all times.

      If he needed to make a mayday call he would then give his approximate position. If he is that incompetent that he doesn't know where he is; he probably also has flat batteries in his emergency gizmo - if he even bothered to turn it on in the first place or understood how to use it.

      Any one relying solely on the 'big red button' deserves; as a minimum; an honorary mention in the Darwin Awards.

      Any one relying on GPS as the sole navigation tool deserves their place in the Darwin Awards - and should be encouraged to try out for membership BEFORE going to sea (I'd suggest playing Russian roulette with all chambers loaded); where they will needless put other peoples lives' at risk

  16. SJRulez

    Any excuse for some people to moan, what did they do before they had GPS????? Maps by any chance.

  17. simonnzg

    According to the advance notice I received about this particular exercise, they're selectively jamming communications and radar frequencies as well as GPS frequencies. They also say that they are "avoiding international Distress, Emergency and Exercise Safety frequencies".

    Someone didn't read the fine print.

    1. TonyG

      It would have been nice if that was included in the office notice.

      The notice at doesn't mention communications - just blocking GPS.

      The Ofcom notice you mention does include these other frequencies but how many people are going to have signed up to this?

  18. XMAN

    How important is the jamming..

    If the Navy are willing to turn it off after a few fishermen complain?

    What other country would limit their military operations because of complaints from fishermen?

    Don't get me wrong, I don't think it's fair for fishermen to lose out, I know how tight the margins are for most one-man traller boats. But surely the safety of the country comes before the profit of a small number of fishermen?

    1. Daniel 4

      If I had to guess, I'd say that the jamming is of "moderate-to-high" level importance. It is absolutely critical that the military practice with degraded electronic communications, especially those they tend to take for granted such as GPS. It's possible as a one-off to just "make believe" that they don't have any GPS, but that seriously reduces the sense of reality, as well as eliminating any ability to practice countermeasures.

      That said, the RN is NOT insensitive to safety issues. If it was just fisherman losing their nets, I suspect that they would respond the same way that the US Air Force did when they were practicing with some black tech that kept opening (and according to a few complaints, frying out) garage door openers across entire suburbs. Specifically, they basically said: "We're the military, cope with it." I suspect that the RN would have responded the same.

      On the other hand, safety issues (at least among their own civilians) tend to get a response from most Western militaries. Some Admirals are probably gritting their teeth at the "dumb fisherman," but they'll plan ahead for next time.


  19. Brian Miller 1

    Radio Jamming

    I am pretty sure that "radio jamming" actually throws out LOADS of frequencies and is not just targeted at one specific band. That would be a pretty inefficient way to disrupt "enemy" comms. as they can just change band, and hey presto!

    I am not at all suprised that military grade jammers knock out damn near everything. This will be why it is dangerous.

    The writer is presumably unaware of this.

    1. SkippyBing

      Not so

      Military jamming generally jams as much or as little of the frequency band as it needs to, after all the more you're jamming the easier it is to locate the jammer, which is generally bad news for them. The latter is why the RN don't have a lot of active jamming equipment and most of that is used against operational units to train them to fight though.

      The RN have been conducting Joint Warrior or whatever it's called these days for decades, they've been jamming GPS for at least the last ten years of that without the world ending. Considering the timing of the exercise is the same every year it strikes me that the original complainer is either very very stupid, or trying to pull a fast one.

    2. peter_dtm

      they don't actually 'jam' the signal by generating competing large RF transmissions. They degrade the signal by playing around with the information that your GPS decodes to work out where it is.

      Mil grade GPS have extra functionality where they can receive corrections for the 'jamming' in real time.

      ALL civilian GPS are only as accurate as the military feel like letting them be - read the small print of the free to use at own risk license no one can ever be arsed to read.

      Obviously you are unaware of the change in use of the term 'jamming'

  20. Matt Bryant Silver badge

    Yeah, "lost" fishing revenue claims ahoy!

    Call me sceptical, but I'm guessing the Scottish fishermen are hoping they can get the RN to say "oh yes, we stopped you lot fishing, we're very sorry", so then the fishermen can start claiming for lost revenue from Whitehall.

    /"Yaaaaar", for lazy pirates.

  21. Anonymous Coward
    Anonymous Coward

    Easy solution!

    Send post cards announcing the jamming to all residents in the area, i.e. both of them ;-)

  22. Spider

    this one sent me off the deep end

    Notices to mariners are issued comprehensively and in good time, in similar manner to notices to aviatiors. Fisherman and WAFIs are aware of them (and if not have no business being at sea). They all do courses and qualifications and pass exams to say they will and then promptly ignore them.

    I've been an officer of the watch on carriers, ice breakers and commercial vessels and seen repeatedly that they think the world revolves around them, that they can ignore safety rules and the anti collision regs at will. They are a constant pain in the arse to professionals at sea and cry out for compensation faster than a french farmer see his subsidy cut. The days of fishermen being mariners have long gone. Most would struggle to use a chart properly if there isn't a screen attached, and many leave the bridge unattended and on auto pilot. At least that's my experience when watching them sail under the bows of ships that have right of way and can't turn.

    If they're unable to work without GPS then stay out of the area for the brief time the exercise is on. Dawkins know the fish stocks could do with a rest from their pillaging.


    1. peter_dtm

      Hear Hear !

      and if they can't manage that - well the gene pool is far better off with out them !

      I can't believe any one seriously paid any attention to these idiots - if you go to sea you read NTM (Notice to Mariners); even more than you look before you cross that busy main road.

    2. David1

      WAFIs etc


      As one of the WAFIs, I sympathize with your rant.

      But I would point out that I have often encountered commercial vessels on autopilot with no lookouts.

  23. James Micallef Silver badge


    Shouldn't a skipper be able to work out their position without GPS? I thought that navigation was part of getting a captain's license? Or do we now have a new generation of sailors who are totally GPS-dependent and can't work out N from S?

    As long as (voice) radio frequencies are clear, it shouldn't be a problem, right?

    1. Carabus

      Skipper dead??

      Most folks here are assuming the skipper is still in charge during the emergency. But the nature of the incident may be that the skipper has sustained injury, illness or died. In such cases the big red button may be the only thing the crew or passenger can operate.

      1. peter_dtm

        or maybe a Carrington effect flare has knocked all the satellites out ?

        Or the engine died & so did the batteries ?

        Or there was a nuclear war ?

        Or someone managed to break the gizmo with the big red button ?

        oh look - it's not safe to go to sea - all sorts of BAD things *might* happen - best stay in bed where it's safe .....

      2. Anonymous Coward
        Anonymous Coward

        @carabus Skipper dead?? #

        Single point of failure?

        No, I don't think that's a valid or vaguely true arguement. But hang on, I'll ask the first mate...

  24. Anonymous Coward

    We look out across the Minch

    ...and usually it's nice to see the sleek shapes of warships during these exercises, especially when they scurry for shelter when the weather gets up. You can keep tabs on them via AIS at this site:-

    It's also interesting to see aircraft we don't recognise, from other nations involved in the exercise. There's also been a high-flying Herc around for days now, a change from their usual 100 foot altitude around here. They had their back door open the other day, flying close enough to see the lights inside.

    We're on the mainland, looking out across towards Stornoway, so don't know the details of what the fisherpersons are annoyed about. For example, I'm not sure whether the GPS issue was broadcast via Navtex.


  25. Shane Orahilly

    Why block them at all?

    If the task is to perform ops without signal X/Y/Z, why not block them at the receiving end, on the ship, at the equipment that would normally use them?

    OK, it may not be quite as simple as switching off the wheel-mounted Clarkson-voiced TomTom, but surely they could get some kind of exercise-only software update to ignore data from selected sources.

    Perhaps blocking is the only way to stop someone.... Cheating? In a military exercise?

    Are the Italians taking part?

  26. Vlad
    Thumb Up

    Moaning fishermen

    How typical of fishermen. They are forever moaning. There are even TV programmes that have them moaning. Have you ever seen a happy fisherman? As I hate the smell and taste of fish I say good job RN!

  27. Anonymous Coward
    Anonymous Coward

    And yet...

    ...Loganair managed to safely fly me From Stornoway to Edinburgh while this was going on, Edinburgh Airport had an outage on their radar and a blanket of cloud covered the country.

    Still, knocking out civilian comms with overenthusiastic jamming kit is a bit rude, maybe best if they take that a bit further offshore next time, eh?

  28. AndrueC Silver badge
    Black Helicopters

    Interesting. It seems RAF Barford near Banbury have been jamming GPS for the last couple of months on and off. I wonder why.

  29. PassiveSmoking

    Well it's a win for the Navy in one way, it demonstrates how badly you can get in your enemies' shit if you jam their access to GPS. Might want to make a note of that one...

  30. JaitcH

    The Lords of the Admiralty should wake up

    as simulating loss of GPS signal can be emulated by switching off the GPS receiver or disconnecting the antennae.

    GPS is used for too many extraneous systems now including ATMs, rail, etc.

    I have a portable cell jammer which has GPS jamming capability, and it is amazing hew large an area a signal of a few milliwatts can affect.

    1. SkippyBing

      That wouldn't take into account the fact that a lot of GPS receivers are integrated into the systems they're part of, i.e. you can't just switch off the GPS part, so to practice with a degraded GPS input you need a degraded GPS signal. Similarly if you disconnect the aerial you don't get a degraded signal, you just don't get a signal which makes for an unrealistic training scenario.

  31. Martin Usher
    Thumb Down

    GPS is useful, but....

    Anyone who sails (and probably flies) knows better than to rely on just one navigation system. GPS is seductive because it works so well but when it fails you find out those people who can't read charts or even look out the window for landmarks.

    I expect weekend sailors to have problems from this but professional sailors should be able to cope; it will be an inconvenience (not being able to zero in on a particular lobster pot in the middle of the night) but it shouldn't be fatal. (....and if it is I'm not sailing with them...)

  32. DenisN

    EPIRBs need GPS

    I yacht, I sea kayak and I hill walk. In an emergency, I'm likely to be unable to get through on marine VHF (hand-held at sea level or below) or mobile phone. I don't rate my chances of anybody seeing a flare in/off NW Scotland. So my only way of raising the alarm is by triggering my EPIRB. If it doesn't have a GPS fix, I'm unlikely to get much of a response.

    1. Daniel 4

      @ EPIRBs need GPS

      "I yacht, I sea kayak and I hill walk. In an emergency, I'm likely to be unable to get through on marine VHF (hand-held at sea level or below) or mobile phone. I don't rate my chances of anybody seeing a flare in/off NW Scotland. So my only way of raising the alarm is by triggering my EPIRB. If it doesn't have a GPS fix, I'm unlikely to get much of a response."

      So don't go out when the military has announced, LONG in advance, that GPS will be down during X block of time over Y area.

      Is this really such a hard concept to comprehend?


      P.S. If the RN is nearby, and you're at sea, I'll bet you dollars to doughnuts that they will not only receive your VHF transmission, but can triangulate on it. You do have VHF on your yacht at least, don't you?

  33. Jon Smit

    Clueless RN - again

    If they are turning off everyones GPS to train RN navigators, WTF don't they just turn off the receivers on the navy vessels and confescate their TomToms ? Are they afraid our Jack Tars will cheat ?

    1. SkippyBing

      GPS !=Tom Tom

      The myriad of systems onboard a warship or aircraft using GPS are not presented by a stand alone box you can lock in a safe, well some of them are but most are integrated systems such as the electronic chart system or the central tactical system which continue to work with a degraded/no GPS signal. In those situations it's necessary for the operator to manually update the position using whatever method they judge appropriate, crucially though most of them don't have a GPS on/off switch it's an all or nothing choice. Obviously it's a bit unrealistic training for war with half your ship turned off just to simulate GPS not working, that normally happens later when you train for what to do after your ship gets hit.

      And they're not afraid matelots will cheat, they know they will, that's how you win wars.

  34. Anonymous Coward
    Anonymous Coward

    oh dear.

    GPS has been around for what, a single generation? less?

    So within their lifetime fishermen have lost all seacraft and have to rely on a lightweight computer that's probably going to mis-direct them via lake taho anyway.

    We. are. screwed.

    -If it weren't for the fact that this is obviously a prelude to compensation claims.

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