In 2009, Two Nuclear Submarines Collided Under the Sea (2016)
nationalinterest.org
nationalinterest.org
A better solution would be for an escort when they get into crowded lanes. Surface ships can use active sonar to scan for other subs while being some what close to their sub. The only problem is other listeners can pick up on what is reflecting off your active sonar as well. Also the subs try to avoid ever being detected because they can save your signature for comparison later.
https://www.frontiersin.org/articles/10.3389/fmars.2017.0029...
My middle of the road Garmin can see 1,100 feet deep in salt and side scan 500 feet in either direction. You can see bottom features and schooling fish. The higher end stuff is so much better.
When submarines actually need to be sure of avoiding collisions they just run on the surface and follow the same rules of the road as any other vessel.
Ref: Dolphin wearing submariner.
Edit: Removed extraneous statements.
On my first submarine duty, we nearly surfaced right in the path of our escort. We had to dive hard to avoid getting run over. “Clearing baffles” is not an exact science.
The active sonar from the escort would reveal the sub it is escorting to any passive observers. It would need a directional sonar (not a cheap commercial sonar) and avoiding prop noise that can also reflect off the sub.
And if all subs were escorted this way, the navies of adversaries would quickly pick up this habit.
Longer answer: A cheap commercial sonar isn’t going to find a submarine, even if you know where you’re looking. Submarines are incredible stealthy, and the ocean greatly effects sonar effectiveness, especially from the surface. Due to how it works, surface sonar is nearly useless when trying to locate a submarine.
A popular joke was for us to surface right in the middle of a fleet during war games, or sneak up behind them and take pictures of people smoking and send them to the surface ship’s captain just to mess with them.
With things like towed sonar arrays, and sonar bouys, the playing field can be evened out a bit, but in all the war games I was in, the surface guys could not find us even we told them exactly where we were.
Now imagine that, with an inexperienced submarine crew doing testing, and a surface ship practically incapable of keeping track of us…
“CON, ESM, EMERGENCY DEEP! Hold high signal strength contact bearing 087!”
(From exDM69's comment, I'll figure that the active sonar's power needs to be dialed way down. The theory that a sub's fancy listening gear could get a good fix on a sonar signal that's too weak to give a usable reflection seems hand-wave plausible to a landlubber.)
Detecting sonar doesn’t.
No hand waving needed.
When transiting places like that, there is either an escort, or the sub is surfaced, or the sub moves reaaally carefully. All depends on the mission.
Check out the book “Blind Man’s Bluff” for more info.
In this context the idea would be that drones can use active sonar, because they are relatively expendable.
The submarine with the larger more sensitive instruments in a quieter environment ought to be able to detect sound levels below that which their active opposition can.
If X amount of noise-energy hits the submarine, it only reflects Y<X of that energy, and only Z<Y of that reflection goes in the right direction to be detected by the opposition. The noise should be louder at the submarine, than at the thing detecting the submarine.
Both of these weigh in favor of the submarine detecting the searcher before the searcher detects the submarine.
I’m sure drones will get there, but right now advantage is the subs
I don't imagine that knowing you'll be detected 40 seconds before they know you've been detected changes the tactical situation a whole lot.
The observation that they are "detecting the searcher before the searcher detects the submarine" is academic and inconsequential when we're talking about such a negligible amount of time between detections.
All my arguments went to the latter kind of problem, not the former. Your 40 seconds number seems to be based on the speed of signal propagation, not the range at which things can be detected.
Even in the event where they do find you, the arguments I gave would suggest that it would take vastly longer than the speed of signal propogation to do so, because they would have to move closer to you. Giving you substantially more notice than 40 seconds.
I was taking it for granted that knowing the location of an unmanned, expendable sonar buoy or probe before you're discovered is not tactically important.
Now that you have me thinking, it would clearly allow you to stay out of detection range if you had the good fortune for their pings to initiate within your detection range but outside theirs.
So, if both sides can detect a -50 dB signal, the passive-sonar target will be able to detect the active-sonar probe 100 km away, while the active-sonar target will be able to detect the reflection from the passive-sonar reflector 0.316 km away. Or maybe 0.315. And that's assuming perfect discrimination.
(By transmitting a signal you can barely detect, you can reduce this discrepancy: if you reduce the signal amplitude by 30 dB at 1 m in this example, the probe can detect the target at 10 m, or maybe 11 m, but the target can't detect it until they're within 100 m.)
However, this massive advantage for passive sonar only really true if it's just as easy for the target to recognize the signal as it is for the probe. In fact, the probe has a huge advantage: it knows what the signal was. If it's just an ordinary chirp, this is of no help, because that's easy to recognize, unless you confuse it for a humpback whale song or something. But if it's Gaussian white noise, it's impossible for a single hydrophone to distinguish from the background noise of the ocean, except by amplitude. Advantage: probe.
But that's a single hydrophone. In fact, though, a point source of white noise is the easiest thing for a phased-array beamforming passive-sonar system to localize. The Triomphant is 138 m long, so if you stuck hydrophones all along its length, you could detect directional sources of sound with an angular precision of about λ/d, the one-dimensional Airy limit. The λ for your active sonar needs to be chosen to be small with respect to the targets you're looking at so it doesn't just diffract around them, so this is probably on the order of 0.1 radians, about 5 degrees.
Two can play that game, though, or thousands. The network of tiny drones can form a single ocean-sized phased array by squirting data back and forth over short-range ultrasound or laser links.
But guess who already has ocean-sized phased arrays of hydrophones for passive sonar?
sca4 posted this very worthwhile link, which talks a bit more about the scene: https://www.aspistrategist.org.au/prospects-for-game-changer...
For anyone wondering what is being discussed here, this is a great document (SOFAR is a sound channel): https://man.fas.org/dod-101/navy/docs/es310/SNR_PROP/snr_pro...
Turns out sonar signals don't actually move in straight lines...
Thanks for the FAS link!
As altimeters got more accurate, the odds that you were flying at exactly 28000 feet went up. If an air traffic controller fucks up and puts two planes at 28000ft, they can now collide because they're ±10ft instead of ±200ft. That was the RCA of that mid-air collision over Brazil a while back.
The more you try to control a thing the more problems you can have. A parking lot for stealth ships is... I don't want to say dumb but confusing for sure.
TCAS II provides the pilot with specific instructions on how to avoid the conflict with traffic. These instructions are known as a “Resolution Advisory” (RA) and may instruct the pilot to descend, climb, or adjust vertical speed. TCAS II systems are also able to communicate with each other to ensure that the RA provided to each aircraft maximizes separation.
From https://nbaa.org/aircraft-operations/communications-navigati...
My understanding is these automated instructions override those from ATC
There's a pilot at the controls so that the technology doesn't have to be perfectly secure.
If you want to walk around broadcasting fake ADS-B or Mode C signals, someone will probably find you in hours, and the only effect it will have is maybe reducing the throughput of the busiest airports if the weather happens to be particularly marginal that day.
https://en.wikipedia.org/wiki/Gol_Transportes_A%C3%A9reos_Fl...
The Legacy's pilot footrest places the end of your shoes dangerously close to the transponder standby button.
https://www.bangaloreaviation.com/wp-content/uploads/2014/04...
The footrest is below the white screen with the navigational chart on it. The radio and transponder panel is the black screen to the right of that, with the yellow and green text on it. The 0512 is your transponder code (squawk); the button to the left of that and down one row turns it off.
This resulted in the Legacy losing its TCAS ability, and the 737 it collided with being unable to see the Legacy.
Yeah the article made me think about that incident too, described here in detail:
https://www.vanityfair.com/culture/2009/01/air_crash200901
It's a great read.
The real risk of collisions comes with transiting through constricted navigational channels, typically when leaving or entering port. Those channels force a lot of vessels into a small area. There have also been a few incidents where submarines failed to do a thorough surface search before surfacing and collided with smaller boats.
During the Cold War there were supposedly a few incidents where NATO attack submarines were following Soviet submarines too closely and ended up colliding.
It's misleading to describe collisions as "theoretically possible" when we have evidence that these collisions have occurred. The fact that collisions have occurred makes me think that these submarines are not randomly located in a large area where it would be difficult to locate them.
A ballistic missile submarine's position isn't completely random, but they do move around somewhat randomly to reduce the risk of detection. They intentionally avoid repeating movement patterns or lingering in the same spot. And this also reduces the risk from spies on land. If a spy sees the patrol orders he'll only know a large general area but won't precisely know the submarine's position at any time.
So you're saying the collision _didn't_ occur at a time when the sub was trying to stay hidden, you're saying that the operators could have / should have used active sonar? Is that it?
Look, either the sub was trying to stay hidden at the time it accidentally collided with another submarine, or it wasn't trying to stay hidden. In either case it didn't do a good job. If it wasn't trying to stay hidden, then it shouldn't have collided. If it was trying to stay hidden, then its location was not as unpredictable as it should have been.
That's...not very large.
> The sub then maneuvers inside that patrol area to remain as hidden as possible.
Given that the same concerns will drive “as hidden as possible” concerns in any sub, that further narrows the space. And unless the decisions made within that space are made in a truly random manner which approaches all equally good options equally (and tolerates a loose enough sense of “equally good” not to excessively narrow the space to start with), common cognitive biases, etc., will result in common decisions.
https://en.wikipedia.org/wiki/Bastion_(naval)
>If someone wanted to locate enemy submarines, surely they could just send a bunch of underwater drones to swim through these parking spots?
back then it were US attack submarines which USSR tried to actively track and push out of the bastions.
That article links to https://en.wikipedia.org/wiki/Submarine_incident_off_Kola_Pe...
Which in turn links to https://en.wikipedia.org/wiki/Submarine_incident_off_Kildin_...
So there have been at least two other submarine collisions.
and
Re >> "At some point, the two navies compared notes"
I get that ballistic submarines want to stay secret and use passive sonar, instead of active sonar. But I also would have thought - if a submarine mysteriously ran into something under water that they did not expect to be there, that they'd start taking a more "active" approach to figuring out what was going on. It'd be like if I tried to walk blindfolded through a large & empty conference room: if I bumped into a whole wall after walking only 3 or 4 steps, I'd be very confused!
Also, since the dawn of militaries, much of what occurs is posturing. You want the other side to think you are big, bad, competent professionals. "We ran into something and we don't know what" makes you less superhuman in the eyes of the public and potential adversaries.
One had a conning tower damage, the other had a bow damage; both were supposedly slow-moving at the moment. Is there such thing as right of way for subs?
The whole point of submarines is that they're stealthy. Active sonor would give away their position. They're basically swimming blind. The only way this all works is the ocean is big enough that random collisions are statistically rare - but there's not much actually preventing them.
It did appear just like that. Shouldn't there be some proximity sensors to avert collisions with massive bodies? After all in the aftermath both subs were rendered mission incapable.
https://www.cbsnews.com/news/whos-to-blame-for-sub-accident/
There is little or no light at typical operating depths. Lidar can work to a limited extent in some water conditions but it's not something to rely upon for collision avoidance.
And, of course, it's an active sensor. An adversary could detect the emitted light.
Is there some spectrum of emissions from an even stealthy sub, some kind of "local presence"? The immediate massive obstacles would result in distortions to such a self-presence profile. So the sensors could be trained to detect such local distortions, almost like some fish have a lateral line of nerves supposedly helping detect current flows etc. [1].
Turns out, this has been modeled already (2007):
[1]:https://www.photonics.com/Articles/Fish_Navigation_System_Re...
Submarine life is insanely dangerous.
What is the catastrophe if this had happened? The weapons won't explode. Is it the danger that they'll leak their radioactive fuel, or that they'll be captured by some enemy power before they can be retrieved (if they can be retrieved at all)?
This whole field is really fascinating to think about.
Water blocks all radio traffic except for extremely low frequency. The bandwidth on that is too low to use as an effective navigation aid, and transmissions can only be sent from large facilities on land. Some submarines can also send up floating antennas on towed buoys but they prefer not to do so due to the risks of detection and entanglement.
One could deploy low-power laser scanning as an anti-collision mechanism when venturing into narrow channels, no?
We basically know nothing about what current NRO spy sats carry, or do we?
There are also magnetic anomaly detectors (MAD) and various wake detection approaches.
Do these work all always? Probably not. But they work often enough to be researched and used.
https://m.youtube.com/channel/UC9bMgCQyFNaMPsK9GtzM5dQ is a good starting point.
Wastewater is probably cooled before release.
Very different from the idea of passing tons of seawater through a reactor and dumping it out. It's not like a jet engine flying through the sky.
Any satellite-based detection system would have to rely on catching the sub while on the surface. I'm positive this is being attempted constantly, but catching a sub at depth is an entirely different manner.
there's a reason sonar is acoustic and not light based
[0] http://hyperphysics.phy-astr.gsu.edu/hbase/Chemical/watabs.h...
May I please have a link to more information? I wasn't able to find anything, and this is very interesting.
https://news.mit.edu/2014/algorithm-recovers-speech-from-vib...
This is fairly open secrets to the degree that it is secret at all so it probably also is no big secret that passive and active countermeasures are used to prevent these techniques.
Subs would be detectable using magnetometers, except that they have electromagnets in them to hide their magnetometer footprint. Still, this is not perfect.
Large subs have somewhat detectable gravitometric footprints that could be observed from space, indeed.