The world is astoundingly safe that these sorts of thing don't happen all the time. Anyone who could light a cigarette could start wildfires all over California and many other places during the summer. Anyone who can buy a GPS jammer could disrupt one of the busiest airports in the world. With all the misanthropes out there you'd think chaos would happen more often. Glad it doesn't.
> Anyone who can buy a GPS jammer could disrupt one of the busiest airports in the world.
Fortunately, that one is not quite the case – the aviation industry is incredibly safety-conscious and does not allow relying on GPS exclusively.
For both en-route navigation and landing, every plane will have at least one fallback system available (usually ground-based radionavigation aides such as VORs or DMEs or inertial navigation systems, which is also what was used for navigation during ocean crossings before there was GPS), and in fact, these other systems are seeing more use than you might assume: https://www.thedrive.com/the-war-zone/17987/usaf-is-jamming-...
GPS interference can, and has disrupted airports. The incident last year in Dallas where there was 24 hours of significant GPS interference of unknown origin disrupted operations. And while GPS is not safety critical, the interference degraded the operation of many different systems that provide additional layers of safety.
The advisory also said the Wide Area Augmentation System (WAAS) and
Ground-Based Augmentation System (GBAS), both designed to make
navigation with GPS more precise, as well as the ADS-B collision
avoidance and traffic management system, would be unreliable.
Pilots reported other systems affected such as transponders that help
radar controllers keep track of aircraft, traffic alert and collision
avoidance (TCAS) equipment, autopilots, electronic flight bags and
terrain warning systems.
Flights into the Dallas area are being forced to take older,
cumbersome routes and a runway at Dallas-Fort Worth International
Airport was temporarily closed after aviation authorities said GPS
signals there aren’t reliable.
Stanford researchers have determined that the interference event
lasted 24 hours, though it took the air traffic system another 20
hours to reset and recover.
A report filed with NASA’s Aviation Safety Reporting System and
published in June outlines how a passenger aircraft flew off course
during a period of GPS jamming and nearly crashed into a
mountain. Fortunately, an alert radar controller intervened, and the
accident was averted.
Landing is moving away from ILS towards GBAS (TLDR computed corrections for high precision local positioning in 4D space within ~30km of the install), provided over unencrypted VHF.
Unencrypted does not mean that the plane avionics will just accept any input without performing plausibility checks.
Even for "plain" (i.e. unaugmented) GPS, there's countermeasures, starting from simple physical ones (e.g. directional antennas leveraging the fact that GPS satellites are usually located above the airplane and not below or inside it), up to complicated logical filters checking all inputs for plausibility and rejecting suspicious signals and resulting position fixes.
Subverting the positioning is different than denying the capability entirely through a higher power transmitter. If you require precise positioning to land and don't have it, kinda moot whether you're faking messages or overpowering. During VFR, not a concern. During IFR, low viz, etc, that is where capability loss is potentially material.
True, which is why almost all airports have multiple different types of approaches, including ILS (which is directional and very high power transmitters in a specific location to jam).
The possibility of a large-scale GPS outage or jamming event is definitely a threat scenario that's being considered by aviation safety agencies. For example, here's the FAA's approach for en-route navigation redundancy, which includes maintaining enough VORs to ensure that there's at least one within every 100 nautical miles: https://www.faa.gov/about/office_org/headquarters_offices/at...
Yes, denying augmented GPS capabilities will probably impact operational efficiency significantly, but it shouldn't endanger safety.
I was watching the most recent 74 Gear video and there was a graphical demonstration of how pilots are reliant on GPS while taxiing.
Sure, I believe that in the air, GPS is redundant. But what Kelsey explained is that, before GPS and graphical maps, pilots on the ground would rely on paper charts that were manually updated and placed in huge binders. They would scour these paper charts to understand what taxiways they needed to take across the airport to get from gate to runway and back again.
Nowadays, the pilots have a nice screen where an image of the airport is displayed underneath a nice arrow depicting the aircraft in its GPS location and velocity. It's more difficult to get lost now, because you can see at a glance on the screen where you are. Looking outside your windows can often confuse, and fog and darkness and unfamiliarity can confound someone who is already lost.
The issue on 74 Gear was that someone got lost and thought they were in an entirely different location, when actually they had intruded on an active runway while just trying to taxi. A very dangerous situation, as you can tell.
I believe that, if GPS were jammed and unavailable, pilots would possibly be able to fall back on these paper charts, that is, if they are even being maintained anymore, but it would be error-prone, and any taxiing pilot would need to exercise utmost caution not to get lost like that.
For taxiing they use GPS just as Google Maps for driving, but it is mostly for pilot convenience to look at a screen and taxi than to look outside at the taxiway markings which in some poor visibility conditions are hard to spot and without the GPS they would I guess require a Follow Me car.
Regarding the runway incursion scenarios, you need to pay attention to the lights on the taxiways, because runway entries are highly illuminated and visible even in really low visibility conditions. You just don't enter an active runway by mistake.
"Paper charts" as you call them, are physical charts of airpots maps akin to a city map. And as a pilot you are required to know how to read and use those maps. Just as with SID/STAR charts. Pilots are expected to know how to fly using only basic instruments (airspeed, altitude, attitude, vertical speed, compass, banking), and even with some of those not operational.
Long story short, GPS jamming at an airport is an inconvenience rather than something critical.
Many large airports have high-precision ground surveillance radar for that very reason, and the software interpreting it can often issue automatic runway incursion warnings, operate visual “safe to cross” indicator lights etc., all without relying on GPS.
There is definitely responsibility on the pilots to not take a wrong turn, and that job gets harder without precision navigation systems, but more than one thing normally has to go wrong for a runway incursion to occur, as far as I understand.
The TSA misses huge percentages of weapons during the passenger hand luggage searches in repeated blind testing.
This means that the standard movie-plot methods of hijacking aircraft are ridiculously easy to carry out: just bring weapons on a plane. There's only a 50% chance you get caught.
This means approximately no one wants to hijack airliners.
I just learned: It seems that state efforts to maximize gun possession have led to so many guns in airports - even TSA agents are starting to find them.
I suspect weapon and gun aren't the same thing here. I've accidentallied a ton of knives through TSA checkpoints because they're small and don't show up well against a my giant ball of cables, adapters, and chargers. OTOH, guns tend to be extremely obvious on x ray machines. They, at a minimum, have a fairly heavy steel barrel and the ammunition is solid lead and/or copper which looks like an extremely dark pattern of dots on an X ray. The springs also tend to stick out very strongly as they have a regular pattern and show up well. I'm sure they missed them before, but generally speaking I doubt it's something an attacker can even begin to count on.
Disassembling a firearm and sticking it's parts inside other regular carry-on items would be sufficient to get past most TSA screenings.
I was blown away with my first First-Class flying experience. You go through all this TSA security theater, and then they hand you a real metal steak knife and glass stemware shortly after take off.
You don't even need to bring weapons, they give them to you.
TSA stuff is all for show. It makes some people feel safer that they had to take off their belt or something...
You'd still need ammunition and the individual parts still look pretty striking. With a modern polymer firearm you're just going to see the slide and barrel assembly anyway. Go look up some pictures of firearms in luggage, they're pretty obvious even if you just consider the individual parts.
A barrel inside a curling iron, the spring inside a hair dryer, the slide inside a laptop, the frame does have small metal bits but, depending on their scanning tech, probably wouldn't appear much like a gun.
You probably don't even need bullets honestly, just the visual aid.
You don't even need a gun though, a knife is plenty lethal on it's own and readily available inside the terminal and even on the plane.
I accidentallied a big knife I had in my bumbag (fanny pack) onto an international flight. And then managed to leave it in the seatback pocket by mistake.
A repeat of the 9/11 attack became impossible before that day was over. It relied on the passengers and crew cooperating with the hijackers until it was too late: they would think that the plane is being diverted or held for ransom and the safest thing to do would be to go along, because that's how hijacking worked from the 60s through the 90s. But now everyone knows about 9/11, so everyone will fight like hell to prevent the plane from being taken over, because the assumption has become that if the bad guys get control everyone will die, and if the hijackers claim otherwise no one believes that.
The bad guys know this: they figure an attempt to do a 9/11-style hijacking will result in failure and death without doing damage to anything but the plane itself. No flying into the Capitol or the Pentagon in a blaze of glory.
Due to procedure changes, and very tough doors into flight deck which are generally locked, and voluntary handgun carry by pilots, US hijacking is not feasible. Yet we pay a ticket surcharge to get TSA groped and our privacy violated.
Americans won't see the enemy which is staring at us. Domestically it will have to get a lot worse over the next decade.
"Never attribute to malice that which is adequately explained by stupidity" – Hanlon's razor[0]
Apart of some war zones or crime holes the world is quite safe and hospitable in general if one doesn't do stupid mistakes or really ask for problems. Every society has some form of agreed laws which try to correct a harmful behavior against them.
Accidental radio interference or setting fire can happen out of simple stupitidy or incompetence.
The existence of that simplification is however often exploited. A lot of malice gets dressed as stupidity. Its also especially easy when stupidity is triggered maliciously.
Most people have easy access to do a lot of havoc if they just wanted to. Drive into a sidewalk full of people, push a bunch of people onto an oncoming metro train car, there are so many ways that we don't even need to get into anything that needs technology.
Ceramic and plastic knives exist and could easily be smuggled aboard an airplane. I think the key insight is that most people don't want to do mass harm and instead just want to live in peaceful freedom and do their own thing.
now the pilots have learned that if there's a person with a knife aboard the plane, they won't open the cockpit doors to avoid a potential hijacking and more casualties. And passengers know that if hijackers take control of the plane, the hijacker might crash it somewhere instead of holding the passengers and crew hostage, like it was done with plane hijackings before 9/11 and might fight back.
So with the example of the 9/11 attacks, the situation has changed enough that a plane hijacking with a knife is much more unlikely
That really has nothing to do with being on airplane though, does it? There are endless places where you can get within stabbing distance of a group of people.
I'd actually expect a plane to the one of the absolute safest places, because like others said, everyone on that place has just become a victim. It doesn't even matter if you like the person being victimized, you're gonna exploit that distraction and beat the fuck out of the dude.
In public people are much quicker to just run away and keep themselves safe.
Humans are born selfish but also social. We're wired _against_ doing these kinds of things. And even when someone has a desire to cause mass harm, fear and self-interest usually stop them.
I liked a comment a few days ago about hostile actors on the internet versus meatspace:
"I asked about the security systems governing walking around in the hallway - was there any physical impediment preventing one person from punching, kicking, throwing a rock at another? Of course not - the security is socially constructed. Norms, consequences, etc, that on balance seemed to work out pretty effectively. I tried to make a case that security inside a local network of the size and scope of our school board was also ~90% social construction, but the student really struggled with it. There was a strong belief that because it was computers, you were expected to exploit it if it were vulnerable."
There was a time you could just walk around with a radio receiver and spy on everyone's phonecalls (IMEI stingray). Iirc it's not possible/that easy anymore with LTE.
Can vouch that the first and second repos definitely worked as of about a year ago, but haven't personally tried since then. I don't have a USRP X310 (yet!) so can't personally speak to the fancy one.
Do/could SIM cards prevent this downgrade if 2G isn’t provided by your local provider anymore?
I know my Canadian SIM card somehow hides US providers from network scans, possibly with some geo or if/then rules (but visible from my EU SIM that tries its darnedest to latch onto the US networks and avoid the Canadian ones at all costs)
This is a problem. You don't want an emergency stop signal to be ignored because somebody didn't update their encryption keys. And it's very useful for railroad workers to be provided with handhelds that can send an emergency stop signal. Here's one used in the US.[1] This is for yard operations, where there's slow-speed (the US limit is 20mph) traffic going in various directions without full signal control. Outside the "yard limit", signals control, and speeds are higher.
If you have no idea what a railroad yard working environment is like, here's a Union Pacific recruiting video.[2] They're up-front about what you're getting into; the intro shows someone at 5:48 AM in a snowstorm in a railyard in Chicago.
I was thinking the same thing and wondering what the use case may be for doing this via radio - thanks for clearing it up! But once you use unencrypted radio, you open it up for remote exploitation - the same thing that can be sent from close up can also be sent from further away with more powerful equipment. That's probably why the systems I was aware of until now use magnets on the track (this can of course only be used to make sure trains stop at a signal, or respect the speed limit, not for arbitrarily stopping them).
The train stops that are mounted on the tracks (https://en.wikipedia.org/wiki/Train_stop) can be used to arbitrarily stop trains. This is obviously much less practical for the attacker.
I actually know someone who was hit by a train in these circumstances in the 90s. He was in the hospital for years. We're all still incredibly amazed that he's still alive -- on the upside, he got one hell of a payout over it.
But yeah, it's REALLY important these radios work :|
The Radio-Stop was not exactly a secret - I remember talking about it with an amateur radio operator ca. 2002.
He was back then saying that the railways will start operating GSM-R in the near future, and the problem of the unauthenticated Radio-Stop will go away :)
Great article. It goes into the radio and the audio frequencies, and talks about equipment that can transmit the signal, from handheld radios to SDRs, and even covers how to build your own (with circuit diagrams).
Even without drones, aircraft, or spot beams on satellites, you might be able to do this with ionospheric bounce or tropospheric ducting. 150Mhz is on the top of 2 meter HAM radio.
Why would you need a satellite for that? A $25 baofeng radio from aliexpress can transmit on those frequencies, and with minimal care (not bragging about it), you can do it from pretty much everywhere with a lot of trains around. The frequency is mentioned in the article, the only info missing is the tones, and i'm pretty sure there is some tech manual somewhere on the "polish internet" that mentions those exact tones.
One of the reasons that the licensing authorities dislike the Baofengs is that they can be easily re-programmed (by unskilled users) to operate on most any VHF / UHF frequency.
They are legal for use by licensed Radio Amateurs (because Hams can legally build and modify their own gear), but the importers used this loop-hole to sell them to other users (eg CB, MURS, commercial two way, etc). Unfortunately, the lax administration by the authorities have allowed this to become a serious issue.
First, and the reason for hate by the licencing authorities is, that they have emissions on other bands (higher harmonics), sometimes way above the allowed levels.
And second, the more problematic here, is that they're cheap. Every airsofter, milsimer, prepper and mall ninja will buy one or two, in "tactical" camo colors with "tactical" antenna, usually one of those huge ones, painted camo, with some kind of "tactical" camo holster, to look "tactical"... while at the same time, they have no idea about frequencies, legalities and just use the preprogrammed channels or input a random frequency in the VFO mode. Before baofeng, this wasn't an issue... cheapest radios were in $150++ range, and paying $600 (or more) for four airsofters was a lot of money... now they can get a set for $100. And in camo and "tactical" designs.
Doing what the person in the article did requires not just $30 of equipment but also at least some knowledge (which frequency, what tones, what timing, how to use audacity or whatever to generate those tones, etc.), and most of the "normal" abusers of baofeng can't do that... just look at the questions on /r/baofeng on reddit... most of them are "we can't hear eachoter", because they're looking at channel numbers instead of frequencies and/or have tones enabled, and "can i listen to <some service not on uhf>?".
I should have said that there are many problems with Baofengs and similar.
Certainly spurious emissions are the big one. The manufacturers have made some attempt to fit LPFs for the ham bands, but simply don't bother for the bands that they don't legally cover.
And yeah, the "cheap and nasty" aspect is simply the other side of the same coin. If the manufactures had fitted LPFs for each possible band, plus sought type-approval for other bands, they would be unaffordable.
Not to mention that removing keypad panel programming would block any attempt at type approval in the first place.
Poland needs to upgrade rail systems, there were plans years ago, but it was costly and postponed. Unfortunately, the radio-stop works well and it's reliable.
Now with around 80% of military equipment to Ukraine is transported through Poland, those vulnerabilities are going to be exploited.
Russia already run remotely groups though encrypted messages and crypto payments:
The aim is to do some diversion or disinformation. There were many instances of producing fake news or misrepresent about some events. Please do your part and refrain from sharing those news about Poland without double checking sources.
Unfortunately, some "news" were picked by mainstream media, even though they could not find any evidence behind that (e.g. turning back non-white people on Poland-Ukrainian border by Polish officials).
> Poland needs to upgrade rail systems, there were plans years ago, but it was costly and postponed. Unfortunately, the radio-stop works well and it's reliable.
True story some amateur radio hams managed to nearly torch our shops substation relay with radios.
Basically our main transformer switchgear was opening and closing on its own every few minutes. We run a diesel truck repair company and it was killing everything from the front office to the air compressors and anything in between. The electric company told us there's an ultra low frequency "DX" the hams sometimes get into that their own power lines use to communicate with substations. Pretty silly. We lost the air conditioner and the boombox that year.
There have been various systems which attempt to reuse existing frequencies by feeding them over un-shielded power lines. And as experts have warned so many times, it will always end up in tears.
If you put radio energy on un-shielded lines, the signals will leak out, causing interference to licensed services. Or will leak in, causing interference from licensed services. And because of the risk of outgoing interference, the signal levels must be kept low, which means that any interference leaking inwards will be much worse.
The only possible remediation is to use good error correction so that the effect is minimised. But of course that slows down the communication rate, so the power authorities don't bother.
And of course this interference can be caused by a large number of industrial electronics, eg motor speed controllers, welders, and so many others.
The point however, is that even if the fault was caused by a flaky VLF control system, then it is very unlikely that it was caused by the relatively low power transmission from an Amateur Radio setup.
To try and blame Radio Amateurs when they are legally operating on a licensed Ham band, using very low power levels is ludicrous.
And to rabbit on about "ultra low frequency DX" only further demonstrates that the power authorities don't have a clue. It's not ULF and whether or not it is DX is irrelevant.
If the power authorities were concerned about interference, they would not have relied on a notoriously unreliable system, or would have run an Optical Fiber along with their Earth/Neutral cables.
There is this mistaken belief that an act of war somehow immediately and automatically triggers war. This is not the case. If a country wants to wage war against an other they will find a reason. If they don't want to / it is not in their interest to do so they won't.
This answers your question. It is not seen as an act of war because the country in question (Poland) wouldn't benefit from seeing it as an act of war at this moment in time.
It's also fundamentally irrational to define malicious non-state actions as acts of war.
As an example, if someone from Canada were to come to the US and blow up a government building, no matter how severe the damage and human loss, we wouldn't dare consider that an act of war by Canada, unless evidence existed that the Canadian government or military were involved somehow.
Likewise, Poland has no interest in defining malicious actions by a Russian national or Russian Imperialism supporter as an act of war by Russia without clear evidence that The Russian state was directly involved.
Getting back to the original point though, I see no reason not to define attacks against infrastructure, regardless of who was responsible, foreign or domestic, or their motives, as acts of terrorism.
> As an example, if someone from Canada were to come to the US and blow up a government building, no matter how severe the damage and human loss, we wouldn't dare consider that an act of war by Canada, unless evidence existed that the Canadian government or military were involved somehow.
But that is where you are going wrong. If the US would want to attack Canada they would absolutely use that as a cause for war. If they don't want to go to war then even an straight up Canadian military attack can be brushed aside as "navigational error during a training exercise" or "regrettable rogue elements in the Canadian military".
This is not the court of law. The important factor is not if the evidence is strong or weak. The important factor is not if the perpetrator was acting in concert with a government or not. The important factor is if the country wants to go to war or not. Everything else falls in place after that.
That's true, but in the Canadian example, presumably the government of Canada would extradite such a person to the US, while Russia obviously would not agree to extradite the culprit here to Poland to stand trial. Whether or not the government of Russia was initially involved, there's a pretty convincing argument to be made that a government harboring an individual who attacked another country makes it a government sanctioned action in at least some sense.
Attacking infrastructure as a non-government entity can certainly be considered terrorism, but if the government backs you even after the fact, that feels a lot more like an act of war with plausible deniability. And in this case I think there might be a motivation for Poland to view it that way, since allowing Russian action against NATO countries invites more of the same, and Russia absolutely does not want to give NATO an excuse to retaliate in any way.
> Whether or not the government of Russia was initially involved, there's a pretty convincing argument to be made that a government harboring an individual who attacked another country makes it a government sanctioned action in at least some sense.
Countries refuse extradition for many reasons: they lack a reciprocal agreement with the other country, laws against extraditing citizens, laws against extraditing residents to face potential execution, etc.
While Russia is the Nazi Germany of examples, refusing to extradite a person doesn't automatically mean anything.
Of course, if someone wanted to go to war with Russia, it makes for a wonderful pretext.
> As an example, if someone from Canada were to come to the US and blow up a government building, no matter how severe the damage and human loss, we wouldn't dare consider that an act of war by Canada, unless evidence existed that the Canadian government or military were involved somehow.
Even if you had evidence that this were the case, you might not do anything, as with Saudi involvement with 9/11.
> Youtube user VolteGe, who says he is too young to drive, has nevertheless created a MIRT controlled by an Arduino microcontroller.
ADSB spoofing can cause massive problems for the air traffic control, and software for that is open source, works on a $200 sdr with a touchscreen and a gui.
FM transmitters are cheap, and remembering the "war of the worlds", anyone can create panic for $20
Because the other side has nuclear weapons and declaring war brings those into play as well. Which is why we've been in a cold war with the Soviet block instead of a real war. The prospect of nuclear war was mutually unacceptable. So, they both sides fought lots of proxy wars instead. And those didn't stop when the wall fell. The Ukraine is a proxy war that has Russia backed by allies China, Iran, and others opposing Nato backed Ukrainian forces. Most of the conflicts in the middle east involve most of the countries I've mentioned and lots of their allies as well. Syria is the forgotten conflict where Iran and Russia are partnering and where the US, Israel, and Europe have failed to make progress for more than a decade.
With Ukrainian forces now striking deep in Russia, that cold war is heating up. This is a reminder that that can work both ways and might soon start affecting Nato territory as well. All deniable of course. But a few high profile attacks like this sends a not so subtle message that Russia can escalate as well if they want.
Maybe they could be, but you have to catch someone doing it first and it would have to be clear they are agents of a foreign government. That's not easy.
This is not even the worst thing Russian agents have done. They used radioactive and chemical weapons to conduct assassinations. They even blew up ammo depots. That is still below the threshold of reasons good enough to declare war on a nuclear country.
I imagine that as with any covert operation it’s hard to prove who’s behind it. Blowing up a bridge is also not something that will cause a war easily.
>>Because the trains use a radio system that lacks encryption or authentication for those commands, Olejnik says, anyone with as little as $30 of off-the-shelf radio equipment can broadcast the command to a Polish train—sending a series of three acoustic tones at a 150.100 megahertz frequency—and trigger their emergency stop function.
Goes without saying here that this needs to be fixed ASAP.
>>The railway agency wrote that “there is no threat to rail passengers. The result of this event is only difficulties in the running of trains.”
There is no threat to rail passengers, unless a passenger train does not know about a stopped train ahead of it on the tracks, e.g., a cargo train go stopped by the hack, but the passenger train 10min behind it did not and continues to rush onward towards the stopped cargo train. IDK if Poland's control system would reliably detects these conditions, but if it does not with 100% reliability, this is a real threat.
> There is no threat to rail passengers, unless a passenger train does not know about a stopped train ahead of it on the tracks, e.g., a cargo train go stopped by the hack, but the passenger train 10min behind it did not and continues to rush onward towards the stopped cargo train.
Almost everywhere in Europe uses actual signalling blocks backed by axle counters and DC detection circuits between the rails of a track, or by physical key/token based interlocks to detect if a train can safely enter the block. The way the US does it (especially detecting if a train has not been separated along the way by using a caboose/end-of-train beacon) may cost less money, but would be viable to such issues.
> The way the US does it (especially detecting if a train has not been separated along the way by using a caboose/end-of-train beacon) may cost less money, but would be viable to such issues.
Detecting separation doesn't rely on the end-of-train device. The EOTD only helps with this by 1/ helping activate the brakes twice as fast by detecting loss of pressure on its end and opening the brake valve, and 2/ sending periodic status indication via radio signal to the locomotive so the crew has more visibility into what the pressure is and whether the tail of the train is moving.
That's why you should be doing a brake continuity check before departing… (Of course that's not entirely foolproof, either, and there have been accidents caused e.g. by a lack of braking power because the brake pipe wasn't fully connected throughout the full train.)
Yeah, on Polish railways there's always brake check on the last carriage.
> (Of course that's not entirely foolproof, either, and there have been accidents caused e.g. by a lack of braking power because the brake pipe wasn't fully connected throughout the full train.)
Can you specify what you mean? If the pipe wasn't properly connected, it shouldn't start at all, because the system needs pressure to release the brakes.
> Can you specify what you mean? If the pipe wasn't properly connected, it shouldn't start at all, because the system needs pressure to release the brakes.
These pneumatic systems leak. You're not allowed to park a train for longer than 24h in Germany if it is purely secured with air pressure for that reason - if it's a particularly bad composition, you seriously risk having no pressure anywhere in the system by that time, and thus no brakes being applied.
Railway signaling works based on whether something is there, not based on whether it should be there. If the freight train stops, then the signals for the passenger train will tell it that it cannot proceed.
I don't know anything specific about Poland's rail signaling, but they can't have messed that up. It's written in blood.
Wow, that's a lot of places where human error was able to make things worse.
Particularly the fact that it's possible to use a "subsidiary signal" to just override the problem. The equivalent British scenario calls for the signaller to vocally inform the driver (e.g. today over GSM-R) something akin to "Pass the danger signal at caution, obeying all other signals". This may mean if there are a multiple related failures, you need to "caution" drivers the same way repeatedly - but without that final sentence the driver may ignore signals that are not related to the failure you understood, and passing those really will kill somebody.
The requirement to move "at caution" meaning with the ability to stop on sight means trains under these conditions don't go very fast - they can't, even on straight lines in broad daylight you can't see far enough to go full speed on a passenger train under those rules, but it also means if you screwed up and there is a serious problem the driver under caution can see the problem with enough time to stop. It further ensures there's an incentive not to allow such situations to persist as they presumably must have for Poland to deliberately fit the "subsidiary" lamps.
