LCS Pursues Next-Generation Submarine Sonar

001017-N-ZZ999-001Navy leaders want the latest Anti-Submarine Warfare Mission Package in development for the Littoral Combat Ship to detect even the quietest of submarines, service officials explained.

The ASW Mission Package — part of the interchangeable sets of technologies being designed for both the USS Freedom and USS Independence variants of the LCS — is being engineered such that it can detect submarines with a Multi-Function Towed Array (MFTA) and what’s called  Variable Depth Sonar (VDS), said Capt. John Ailes, LCS Mission Modules program manager.

“Variable Depth Sonar allows us to put the sound down where the submarine is. If you look on current destroyers, they have a hull-mounted sonar on the bow. It turns out that there are acoustic layers based on temperature and pressure that bend the sound up. A submarine can dive below this layer and there is a lot of attenuation and signal loss from a hull-mounted sonar,” Ailes explained.

The Variable Depth Sonar allows sailors to place the sonar “beneath this layer,” Ailes said.

MFTA is a towed array sonar system, tethered to the ship, that is able to receive and transmit signals, including sounds and signals emerging from the VDS, Ailes explained.

The MFTA, called the AN/TB-37, is currently fielded on 30 US Navy cruisers and destroyers, said Navy spokesman Matt Leonard.

“The VDS variable depth sonar is an active sound producing system that provides the acoustic signal that is sent out and reflected back from the target submarine.  The reflected sound is received on the MFTA. The VDS and the MFTA are towed separately but they can be towed at the same depth, or at different depths.  Generally they are towed independently at the same depth,” Leonard said in written statement.

The combination of these two detection systems will allow the LCS to better detect quiet submarines such as diesel subs running only on batteries, Ailes added.

“Together, the VDS and MFTA provide both a transit speed ASW escort, and a barrier/area search capability, as well as a torpedo alert capability,” Leonard said.

Don’t mistake the capabilities of the VDS with the hull mounted SQS-53C sonar on cruisers and destroyers. The VDS can be towed at depth.

“Cruisers and destroyers can tow their MFTA’s at depth, but if the submarine is deep, they can only receive the sound the sub makes.  In comparison, the VDS is effective against quiet submarines as it produces the sound which is then received on the MFTA,” Leonard added.

The Navy is currently testing with a VDS that is made by Thales, Leonard indicated.

“This system has been in service since 2004, but this is the first time it has been used by the U.S. Navy.  We will be having a competition for the Mission Package’s production VDS and it is likely that Thales will be one of the offerers,” Leonard added.

Overall, the Navy plans to acquire as many as 16 Anti-Submarine Warfare Mission Packages to serve on portions of the planned-for 55 LCS ships.

The ASW mission package is also configured to work in tandem with UAS such as the Fire Scout and airborne torpedoes on-board the Navy’s MH-60R helicopter.

The MH-60R can also lower active and passive sonar sensors using a sonobouy device; in fact, the MH-60R can make use of a dipping Variable Depth Sonar which drops into deep water from the air, Ailes added.

In addition, the ASW Mission Package is equipped with a defensive technology  called Light-Weight Tow that is able to defeat incoming enemy torpedoes, Ailes explained.

“It defeats a torpedo when it is shot at the ship. If there is an torpedo inbound, it defeats it and there is no operator action required,” said Ailes.

About the Author

Kris Osborn
Kris Osborn is the managing editor of Scout Warrior.
  • greg

    Let’s hope this new sonar doesn’t kill whales and dolphins like the one the Navy is now testing.

    • BOB

      yes, because clearly saving a few marine mammals is soooo much more important than being able to track the Chinese/Russians/whoever we need to.

      take off the skirt, put on your big boy pants, and get your priorities right

      • Ross

        In your opinion, what are acceptable losses for marine mammals before it becomes an issue?

      • JoeSovereign

        Killing marine mammals at a high rate to play war games is definitely a problem. We are still looking for new enemies to justify our War Economy we have been in since 1939. In what scenario are Russian, Chinese, or Taliban subs going to be firing weapons at any US asset?

    • Ross

      I would contend that less than a 25% rate of loss would be acceptable, providing that the sonar doesn’t harm female marine mammals at a higher rate.

      Have you noticed a correlation between offensive capability and worrying about threats? Canada has what? One working Diesel Electric Boat working and no one hates them?

      Besides if we use a harmful sonar to track Russians who can’t afford to send out their fleet, and Chinese, who are too busy fighting over islands in the Pacific, and end up blasting out the brains of all the “dolphins” in the ocean….what is the Navy going to use to replenish their really cool Marine Mammal Program?

      • Andy

        You do aware that we spot the Russian NUCLEAR Sub. close to our coast right ? so in your opinion you rather protect the Dolphin first then the US.

        • Ross

          well…if we’re spotting them then the technology we have is apparently good enough. I’m not saying not to keep improving it but maybe killing other organisms is something we might want to add into the cost benefit analysis.

          • EW3

            It’s the ones we don’t spot that are the concern.


          Ridiculous. How we are letting the Ruskies get away with this? The Syrian government is flaunting their new weapons from Russia, and they just float off our coasts.

        • Phono

          aren’t the dolphins part of the us that you want to protect?

      • Belesari

        Canada has the US to protect them. Same for europe and all the others. The US had kept the power and reigns now for a while.

        Used to be Germany was like the other EU nations now that they are doing well and doing what needs done they are more powerful. Now people are hating them.

        This isn’t a game or a populartity contest.


      Aren’t enemy ships considered sharks?

    • blight_

      If you’re popping active sonar, then it’s wartime and the use of torpedoes underwater will generate unpleasant shock waves.

      In peacetime, we should work to clear areas of marine life before testing (perhaps use USVs to chase them away?). Take care of marine life, then you don’t have to trade readiness for sea animals lives. Or find somewhere out of the green-water/early-blue where the dolphins don’t hang out.

      Pragmatically, if it can rupture an eardrum from 100 miles away, it’s probably detectable by an enemy. We will not be doing active sonar for fun, and the use of active sonar in a mixed environment could have serious consequences.

      Do you have SEALs in the water? Whoops! Using dolphins and seals to find mines and frogmen? Whoops! Did the coast-watchers find a ton of dead sea lions? I guess the Navy is in town.

      I don’t think the Navy *wants* their ace in the hole sonar to be so powerful as to affect marine life. But until that changes…

    • El_Sid

      The article doesn’t go into much detail, but this VDS brings the USN up to where the RN was a decade ago. It’s the low-frequency active sonar from the Sonar 2087 on most British Type 23 frigates, which is also used on the ASW version of the Franco-Italian FREMMs. So it’s had to pass all the European tree-hugging regulations and yes, it’s much more dolphin-friendly than the US LFAS systems. Many £millions of British taxes have gone into studying that stuff - IIRC the EIS is up on the web somewhere.

  • Andy

    Your question remind me of 9/11.
    await for the Terroris attack us first then reponse ? just like prevent the CANCER or try to cure the CANCER?

    • Ross

      False Analogy:

      9/11 was perpetrated by a terrorist organization without access to the technology and resources available to an advanced nation state. The sonar in question is used to find hyper-quiet submarines. A stethoscope dipped into the ocean could find the types of boats that terrorists would have access to.

  • Mystick

    So why isn’t this being deployed to a blue-water vessel? Seems to me, looking for “really deep boats” isn’t going to happen in a littoral environment, within which the “Littoral Combat Ship” was specifically designed to operate. Seems like more candy-coating on an already-obsolete-before-deployment project.

    • El_Sid

      For these purposes “deep” means below the thermocline, but in the littoral that can mean “not very deep at all” - lumps of water with different termperatures and salinities mean that you get a mass of different layers which are easy for a sub to hide in. Passive sonar is great against nuclear subs in cold, uniform water like the North Atlantic, but against quieter diesel subs you need active sonar and in the littoral you need a VDS to get down among the acoustic layers.

      Don’t knock 2087/CAPTAS though Nadnerbus - in ASW terms its the equivalent of going from the F-15 to the F-22.

      Also don’t forget that most LCS are replacing minesweepers and patrol craft, so its a different mission. But at least it’s easy to add more modules if the threat evolves.

      • blight_

        On paper most LCS are replacing minesweepers and patrol craft, but only because they are going to carry drones to do those tasks.

      • d. kellogg

        …”easy for a sub to hide in…”

        Again, if the water is deep enough that a sub can detect and maneuver along thermoclines, then the water is deep enough that destroyers and cruisers should be the primary ASW asset.

        A 5-10feet deep layer of water of a different temp isn’t going to hide a sub with a hull depth of 15-20 feet.
        And if the water is too shallow, the sub is going to churn up the bottom silt with its pressure wave and maybe even prop wash, something a surface vessel can track (sonar will pick up on the increased silt/turbidity at such ~shallow~ littoral depths).

        And has anyone even clarified what measurements, in depth, the USN’s definition of “littoral” actually even implies?

        • Mystick

          I think the Navy’s definition of “littoral” meant they wanted a sovereign presence and slice of the pie in landlocked places like Baghdad.

          With that out the window, they want to showcase this combat system/hole in the water that they’ve poured money into as much as possible.. but shallow-draft vessels designed for river, estuary, and close-in-shore environments have no place in blue-water operations. This is especially true of the GD/LCS-2 design. The whole project was a hand-out to Lockheed and General Dynamics and as a playground project for new DARPA toys.

          I say let the Coast Guard do their thing and the Navy do it’s thing. Mission overlap is wasteful.

    • SJE

      I would imagine that the Iranians would disagree: a small diesel-electric sub just sitting at the deeper parts of the gulf can be very hard to detect, and yet pose a serious threat to shipping.

  • Gman

    Way over hyped problem, we use Passive ( no sound in water) Sonar.
    Normally only use Active( sound in water) Sonar when attacking or being attacked.
    Been there , Done that, the Marine animals hear us coming for miles and swim away.
    We share the oceans with these great animals and also don’t want to harm them.
    We are very careful and do everything possible to avoid hurting them.
    P.S. Loud is Dead, Active gives away your location further then your can detect a contact.

    • Ross

      Thank you Gman for putting it into perspective. Glad to hear your views regarding the wildlife you “swim with” too. The Navy has really been excelling at development of green(er) fuels (despite congresses best efforts) and recycling technology on-board its ships and as a former Marine… I really need to go wash my mouth out after praising the Navy.


        Well. Nuclear fuels have been contained well, so I don’t see any troubles anyways (ahem, Russian sub fleet). Green fuels would be what though?

    • Belesari

      Yea the only times I’ve heard the problem is when we do exercises.

      I’m sure when the Russians or Chinese go active they watch out for marine mammals.

  • Fahja

    These ships still need a small modicum of permanently installed ASW equipment. (2) fixed torpedo tubes and a small conformal hull mounted sonar could provide some defense under a “what if” situation. During high sea states, high speed runs, helicopter re-fueling would be the perfect time for a submerged attack. ASW is about persistance and reaction times wrapped in patience. This sole reliance on VDS post too many restrictions on ASW fundamentals and tactics.

    • blight_

      A torpedo tube would be an interesting option. Deliver mines, anti-ship capability. That said, since a TLAM can be fired from submarine torpedo tubes, can one be fired from a ship’s torpedo tubes as well?

      • Fahja

        Tlam is designed for 21 inch tubes(subs). shipboard Mk 32 are 12 inch. yet Captor Mines are an option.

  • Lance

    Still proves LCS is a waste DDG-1000 can have this sonar too!

    • blight_

      Indeed, they probably will. Need to protect themselves and the carrier…

    • fahja

      DDG-1000 needs to re designated as proper cruisers. probably make a better argument with congress.

      • blight_

        Unless they have plans to bring back CG-X in some form, and DDG-1000 would get in the way.

        • G Lof

          Not if you called it something like CLA for Cruiser Land Attack, that make the difference obvious enough.

  • BlackOwl18E

    Seems to me that they’re adding it on more to give LCS at least one fully functional capability since almost everything else falls short of the actual requirements for combat in the littorals.

    • blight_

      “Hey, we detected something…we have no weapons to fight it except a helicopter and an ISO container full of electronics managing some drones”

      • BlackOwl18E

        Hahaha! You’re right. Without some sort of torpedo armament this capability is incomplete for the ship to do anti-submarine warfare on its own.

        • blight_

          You can run away from the submarine you’ve detected, or get a helicopter to deal with it.

          It won’t be long before submarines start carrying micro-VLS tubes to fire anti-air missiles against pesky helicopters and maritime patrol aircraft. Sure it gives you away, but ASW helicopters aren’t cheap, nor are they numerous; and destroying one means the next one will proceed twice as cautiously with protection, giving you enough time to change positions or escape entirely.

    • PolicyWonk

      Indeed. But MFTA isn’t unique to LCS. The navy, when initially cooking up the notion of LCS, was looking for a solution to swarms of small speedboats in confined areas (littorals), and came up with this lousiest of all compromise “solutions”.

      Too big for the mission it was intended for, unarmed for adversaries larger than a speed-boat, unprotected from a naval adversary, and at $400M per sea frame, heinously expensive for a system that cannot perform any job well.

      On the happy side, any ship can be a mine-sweeper - ONCE ;-P

  • d. kellogg

    The whole missing link in their ASW plans is,
    is this yet again a mission primarily reliant on the ship’s limited umber of helicopters (2) actually delivering the kill shot?

    Put those 12.75inch torpedo tubes on these ships already!

    Oh wait…we’re in the littorals: is the water even safely deep enough for threat submarines to even operate in?
    ASW belongs to larger, better-equipped blue water ships, not the theoretical brown/green water speedboat navy.

    If the water is deep enough for even one of the smaller current SSK types to operate in without fears of running aground or into underwater obstacles, then the water is deep enough that Burkes and Ticos can be engaged in far more effective ASW than any containerized LCS module can offer.

    • Mystick

      In a littoral environment, it’s almost more effective to conduct a visual search for submarines…. preferably from the air. These environments are so noisy anyway, passive is almost useless unless you’re practically on top of them, and that’s if they are noisy. It’s more efficient to run shore-based or even carrier-borne aerial ASW for littorals.

      These vessels are more suited to intercepting smuggling than anything else. That being said, they would make excellent CG vessels.

      • d. kellogg

        …Yet I seriously doubt the USCG has either the desire or the expense account necessary to operate these vessels.

        They’d be better off served with something bridging the capabilities between the current NSC and that theoretical NG Patrol Frigate.

        Seems to me, unless training foreign navies on their own turf, the USCG mission needs to focus on the North American coastal areas (including Caribbean and polar territories). That should be authorized then to perform limited ASW as required: we’ve seen numerous examples of drug cartels building semi-submersible delivery “subs” to smuggle in drugs.
        Give the USC a standing “fire as deemed necessary” order of ROE, as seriously, how many recreational subs are there in the world?

        No, neither USCG nor USN needs these LCS platforms. Let the ships serve as technology testbeds, nothing more.

  • brownie

    The USN needs a FRIGATE. These vessels are designed to serve specific needs: gunboat (targeting small craft); ASW, Special Forces Insertion & Support: Anti Mine. WE NEED A FRIGATE.

    • Nicky

      Which is why the LCS is a joke and a WASTE of Money. What we really need is a Multi Role Frigate that can do all the Frigate missions such as ASW, ASUW, Limited AAW, Land attack and NGFS for the Marines ashore. A frigate is what we need to escort and protect NFAF, Marine Amphibious Ready group and the Merchant Marine Fleet. A frigate is perfect for Protection of vital shipping lanes, Anti Piracy and as a diplomacy tool, show the flag around the world. The LCS as it is, is nothing more than a Corvette wannabe and a glorified coast guard cutter painted haze gray. If the US Navy wanted a true Corvette with Ocean going capability, then they could have gone with a SIGMA Corvette or a Holland class OPV with STANFLEX technology.

  • PolicyWonk

    In comparison, the VDS is effective against quiet submarines as it produces the sound which is then received on the MFTA,” Leonard added.
    And can be detected by subs long before the ship ever gets a signal returned. How this will be useful in the littorals is questionable - this is seemingly more of a deep-sea solution.

    But then again, the mission for the LCS remains ill-defined, its armament weak, and protection all but non-existant. Whether its fast enough to run away from the many threats a real adversary (i.e. a real naval threat) might have to offer, remains to be seen.

    But the inability to take a punch and keep fighting has already been determined, which is also why all potential foreign purchasers of the LCS have all walked away.

  • Ruger

    Pic looks like it’s taken from Narr. Bay. I hope they test here to drive of the sea lions that are new to the area. If there are casualties. no tears here.

  • Phil Munck

    Wow! Variable Depth Sonar. What will they think of next? This couldn’t be anything like the VDS that was pretty much standard on destroyers in the 1960’s, I guess.

    • Will

      Absolutely. This post implies that VDS is something new. Sheesh.

  • wpnexp

    We can mitigate the whole sonar issue if we employ lower powered sonars on UUVs and then ping more without actually giving away the location of the LCS (especially if the ping is directed away from the LCS). Then the towed array can geolocate the enemy sub. This would allow for more use of active pinging at lower decibel levels and a greater chance of detection.

    • fahja

      This can be enhanced with nominal hull mouted conformal sonar. This could provide (3) bearing lines which would provide an enhanced datum on target.

  • Mystick

    I had a theory about using a spread-spectrum type signal configuration for active sonar, operating near or even below the noise floor. Less chance of interception and would give a larger footprint when it comes to thermoclines and CZ(which aren’t utilized much in Yankee)… they are dependent on temperature AND frequency.

  • Big-Dean

    so what’s the mighty LCS going to do with a submarine once they bump into it, throw aluminum foil at it?

  • Brian

    Exactly what is the point of building a glorified patrol boat with a price tag that exceeds many decent European Frigates? If you’re going to build a Frigate, then build a proper Frigate! Or if you want a long-range hybrid patrol / multi-role ship done properly, take a look at the Danish Absalon class ($267m per unit for a 17,000km range LCS style ship with VLS tubes & proper medium-long SAM’s & radar & ability to move dozens of heavy tanks at a time…)

    The Littoral Combat Ship - a ‘solution’ looking for a problem since 2008. Biggest white elephant in the Navy…

    • Nicky

      That’s why you have every Frigate, FAC and Corvette ship Captain’s around the world Laughing at us. It just shows the US Navy doesn’t have a freaking Clue on how to build a REAL Frigate and a Real Corvette. The US Navy needs to admit to the Taxpayers, they screwed up on the LCS and need to Hire Frigate experts and Corvette experts on how to design and build a REAL Frigate and a REAL Corvette. Most European, Middle eastern and Asian pacific Navies operate Real Frigates and Corvettes that would outclass and outstrip the LCS any day of the week.

  • Big-Dean

    LCS just like the F-35

    both programs are designed to fail and to suck the life ($) out of the budget

    • d. kellogg

      Make work programs for their given defense contractors.
      Or rather in all these cases, “maybe work” programs.

      I don’t know what’s worse: letting the defense industrial knowledge base dwindle under sequestration for several years,
      or provide corporate welfare to subpar engineering and R&D departments who’ve obviously failed to learn any of the useful lessons history (and adversaries) have taught us in maritime (and aviation) engineering.

      Years ago toured the museum in Battle Creek Michigan and marveled at that turbo-compound prop engine cutaway to show the internal workings of a mutil-bank radial and all its associated gearing, propeller feathering system, and a myriad of other complexities all designed without computer.
      All functioning reliably enough to get planes aloft for thousands of miles at a time.
      Designed in barely 5 years of development, fitted to aircraft barely 5 years in development.
      Now we can’t even design an aircraft, its engines, avionics, and software in less than a decade and a half.

  • Opinion3

    Woo you guys hate the LCS. Whilst I can understand some of criticisms some are a little harsh.

    With those turbines the LCS will out pace just about any thing else out there. We have destroyers with ummm anti-air missiles and thats about it. OK it does have a machine gun or two and a gun on the bow. not much else

  • XYZ

    I started laughing when I read LCS.

    J/K. But not. It’s a great idea, just botched it a bit. To actually defend in littoral regions we need way more of them than we’re planning on building. Think: defending against large swarms of missile boats.

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