Here’s a just-for-fun post. Let’s speculate about LCS shallow water ASW tactics. I don’t think the Navy has gamed out an LCS ASW concept of operations so let’s do it for them! Now, before we go any further, let’s acknowledge that none of us has the background to discuss this authoritatively and if we did we probably wouldn’t be able to discuss it publicly. So, as I said, this discussion will be just speculative fun.
Let’s start by summarizing what we think we know about the LCS as it relates to ASW.
- Let’s start by recognizing that we’re focusing on shallow water ASW because there are better ASW platforms for deep water operations and the LCS hasn’t got the endurance to conduct sustained deep water ops.
- The LCS is not built for ASW. It does not have machinery quieting built in, it lacks a hull mounted sonar, its water jets make it an acoustic beacon (it’s a better target than hunter), and it has no ship mounted ASW weapons.
- The only ASW weapon the LCS has is the helo and it can only operate one helo. Reports state that the LCS-2 variant can operate two -60 type helos but I’ve heard that flight deck structural issues limit it to one helo.
- The ASW sensor suite consists of a variable depth sonar (VDS), SQR-20 multi-function towed array (MFTA), and the MH-60R helo’s AQS-22 low frequency dipping sonar (ALFS) plus sonobuoys.
- When deployed, the VDS limits the LCS to very low speeds.
- The MFTA requires a pretty fair water depth in order to be towed without dragging on the sea bottom. I don’t know what the minimum operational depth is but I’ve heard the general statement that the MFTA is not really useful in shallow water. I’ve also heard that it is possible to only partially stream the MFTA in order to keep the array from sinking too deeply but then a partial array is only partially effective.
Now, let’s summarize what we think we know about the shallow water ASW environment. Due to its nature, shallow water is a very noisy place. Bottom flow, river discharge flow, numerous civilian an commercial vessels, surf/shore interaction, tidal movement, civilian craft, bottom debris including lots of wrecks and metal structures, and lots of biologics (animal life) all contribute to making shallow water a very noisy place. Thus, detection is likely to occur only at much shorter ranges than in deep water. Passive sonar is going to be far less effective resulting in an emphasis on active sonar which, again, is inherently shorter ranged. Further, the mixing of fresh water from rivers with the salt water and the effects of solar heating will cause lots of transient thermal and density gradients which will further complicate acoustic detection and result in shorter range detections.
Finally, let’s summarize what we think we know about the SSK, the likely shallow water opponent. SSKs are very quiet, slow moving, and quite deadly with long range, fast torpedoes. Well, that wasn’t hard to summarize!
So, now we understand the LCS, the environment, and the enemy (hmm, the Navy has people study ASW for years and we just became experts in a couple of paragraphs!). With that knowledge, what ASW tactics can we postulate that would emphasize our strengths, mitigate our weaknesses, and maximize our chances for success?
The helo is clearly the strength of the LCS. It allows the ship to remain at arm’s length and is immune to counterattack (at least from the sub!). Unfortunately, the helo is also an inherently weak platform when available in only limited quantities. The old saying is that if you have one helo, you have none. That’s in recognition of both the helo’s chronic maintenance issues and the limited endurance (Lockheed’s product brochure lists mission endurance as 3.3 hours) and small payload that requires frequent returns to the ship for maintenance, refueling, and rearming. Remember that ASW is a very long term operation requiring persistence, patience, and endurance. Even a functioning helo is only available for several hours out of each 24 hour cycle. Thus, a ship with only a single helo will only have sporadic ASW helo coverage. When you subtract the maintenance, refueling/rearming, and transit times, you quickly realize that the best a single helo can offer is 4-6 ours of actual ASW coverage per day.
The obvious solution to limited helo availability is to increase the number of ships, each with a helo, and pool the helos so as to maximize helo availability. Four helos, and hence four ships, sounds about right to ensure one helo is always on station. This, then, dictates an LCS ASW tactic of operating four ships as an ASW squadron.
How, then, do we utilize the four ship squadron, tactically?
We must first acknowledge that even four helos operating simultaneously can only provide a very limited coverage area. Dipping sonars in shallow water are just not going to provide wide area coverage. More realistically, as we discussed, one or two helos are going to provide extremely limited coverage. Thus, in order to maximize our chance of detection, we’ll have to involve the ship’s sensors. A reasonable approach to this is to stake out a square of interest with a ship at each corner and work in towards the center with the helos starting at the center and working back out towards the ships. Hopefully, the constricting box will herd the submarine towards the center where the helos can locate it or, eventually, all four ships can combine to locate and prosecute it.
The alternative approach is for the ships to stand well off and let the helos work the area of interest alone but their limited coverage is unlikely to succeed.
Having located a target, how do we attack it? As we noted, the LCS has no ship mounted ASW weapons so the attack will have to be by helo. There’s nothing wrong with this except for the helo’s limited availability and limited payload (two torpedoes, max). We may have to make multiple attacks over several hours due to limited availability. Maintaining contact on a very quiet target for that length of time will be a challenge and, again, multiple ships will be useful to track the contact.
Related side comment: If I were the Navy, I’d have designed the LCS with the ability to share ASW tracks and data in a common tactical picture. I wonder if they did? I’ve not heard of such a capability.
Lastly, we have to recognize that asking an unoptimized, acoustically loud ship to play tag with an SSK is asking for LCSs to be sunk. It’s a fact of combat. Again, this argues for operating in multi-ship squadrons. If one ship is sunk or forced to run, the others can maintain contact and continue the prosecution.
One of the weaknesses in this concept is the LCS’ inherent susceptibility to enemy aircraft since the LCS has only very short range AAW capability. It would be nice if the group could combine AAW resources for self-protection but that isn’t possible. In an area of likely enemy air activity a Burke may be a requirement for self-defense. If so, the Navy should also think about incorporating the Burke into an LCS/Burke hunter killer group – but that’s a topic for another time.
Of course, all of the preceding discussion presumes that the LCS is operating alone in the ASW role. It is quite possible that other air or submarine assets might join in which would necessitate modified tactics. We can’t cover all the permutations in one blog post so we’ll stick with just the LCS. This should also provide us with the tactical baseline from which to modify tactics as other assets enter the equation.
The sharp among you may be wondering about the value of 4 LCS/4 helos versus a single small helicopter carrier that could carry, say, 12 helos. If, as we’ve described, helos are the key to shallow water ASW, then a helo carrier would be suitable and offer more helos. For probably the same cost as four LCS, a helo carrier would provide 3X the helos. Something to think about.
So, what do you think? Anyone have a different idea about how to go after shallow water subs with the LCS?