Tag Archives: survivability

Deconstructing ‘Survivability’

In a recent CIMSEC NextWar article, “The LCS Survivability Debate,” Chuck Hill admirably contributes some much-needed nuance to (and sparked a flurry of articles about) the debate surrounding the Littoral Combat Ship. At the center of this conversation is the question of just how we define the survivability of small surface combatants. Under any traditional rubric, such ships would appear to be sitting ducks, without the durability or defensive capabilities of even slightly larger cousins. Yet, as Hill illustrates, this traditional perspective lacks important insight into the more qualitative assessments of resiliency. His piece provides well-argued documentation demonstrating a key factor: that small surface combatants make bad targets. These ships sale under the radar, so to speak. To demonstrate his point, Hill concludes with some anecdotal evidence:

“As part of Operation Overlord, the Normandy Invasion, 60 US Coast Guard 83 foot patrol boats were assigned to rescue those unlucky enough to find themselves in the water or sinking. 30 went to the American beachheads and 30 went to the British and Canadian beachheads. Being wooden hulled and gasoline powered, they certainly would not have been considered ‘survivable.’

“Apparently they were in the thick of it, because they rescued 1438 men from the water and sinking craft. In spite of all the fire from shore, not a single boat was sunk and not a single crewmen was killed. Apparently the German gunners were too busy with the landing craft hitting the beach and the warships that were shelling them. They simply were not a priority target.”

This argument resonated with me. I manage research for the intelligence and security services firm Security Management International (SMI) and a large portion of what we do is target analysis and vulnerability assessments. We employ an approach known as CARVER – criticality, accessibility, recoverability, vulnerability, effect, and recognizability – which blends qualitative and quantitative assessments of risk, much in the same spirit as Hill, and provides an interesting lens through which to deconstruct what we mean by survivability.

Criticality measures a target’s significance as a component of a larger system or network. Accessibility represents a target’s ease of access. Recoverability is the time it would take the system to respond to an incident and restore a component’s utility. Vulnerability is an account of a target’s susceptibility to attack based on adversary capabilities. Effect is the degree of devastation or impact such an attack on a given target would have on the overall system. And recognizability is the likelihood an adversary would recognize a component’s criticality. What do we learn if we apply this technique to the LCS debate?

Traditional arguments critiquing the LCS’ survivability can be seen as highlighting the more quantitative elements of CARVER (accessibility, recoverability, and vulnerability). As a craft designed to operate close to shore, the Littoral Combat Ship certainly fits the bill for accessibility. While a fast ship, the short range between shore-based batteries and the vessel place it at greater risk than ships operating farther out. Hill covers the topic of recoverability, which highlights similar concerns. He relays part of a U.S. Naval Institute piece on the topic (also a commendably nuanced read), noting that “small warships are historically unsurvivable in combat. They have a shorter floodable length, reduced reserve buoyancy and are more likely to be affected by fire and smoke damage than larger combatants.” A direct hit would likely leave an LCS reeling to a more devastating degree than an equivalent hit to a larger combatant. Even non-state asymmetric actors may pose a degree of risk to the craft given its intended area of operation in congested littorals, which pose the threat of terrorist incidents similar to the USS Cole bombing.

Yet, as the CARVER methodology would suggest, there are additional elements to threat and vulnerability assessment. These are the more qualitative components to which Hill’s article seems to allude. They include criticality, effect, and recognizability. Here the LCS performs significantly better. As a small surface combatant, the Littoral Combat Ship can be seen as far less critical than a capital ship. Therefore, the loss of an LCS presents less of an overall effect on the fleet. Neither of these points is meant to trivialize the potential for loss of life. Rather, the psychological component of how an adversary (especially a symmetric adversary) might perceive an LCS suggests it would present itself as less of an attractive target because of its less significant role compared to an aircraft carrier or nuclear submarine. This all comes together in the final point, reconizability. If an adversary fails to recognize the LCS as a high-value target, which its criticality and the effect of its loss would suggest, this should be reflected in the overall assessment of its survivability.

None of this unequivocally resolves the enduring conversation about how and where the LCS should operate, and against what type of adversary. Thus, the debate around its survivability will linger. Yet, as we can see, and as Chuck Hill rightly identifies, there is a greater degree of complexity in what makes something resilient other than the thickness of its armor. If sixty wooden-hulled Coast Guard patrol boats could survive the invasion of Normandy, surely our depiction of the LCS’ durability deserves greater nuance.

About the Author

Since 2011 Joshua has served as the manager for research and analysis at Security Management International (SMI), an intelligence services provider in Washington, DC. Josh has co-authored several articles in the Journal of Counterterrorism and Homeland Security International with SMI associates. Since 2013 Joshua has also been a frequent contributor to spaceflightinsider.com, a member of The Spaceflight Group’s community of aerospace news websites. He is a PhD candidate at the University of St. Andrews’ Centre for the Study of Terrorism and Political Violence, where he researches maritime security. Joshua is a Summa Cum Laude graduate of The George Washington University where he received a BA in Middle East Studies from the Elliott School of International Affairs.


LCS Survivability Debate: By the Numbers

Both Doyle Hodges and Chuck Hill have recently commented on Littoral Combat Ship (LCS) survivability in light of World War II damage reports, responding to Steven Wills’ opinion piece at USNI News (which he followed up yesterday).  The genesis of their response appears to be Wills’ claim:

“Small warships are historically unsurvivable in combat. They have a shorter floodable length, reduced reserve buoyancy and more likely to be affected by fire and smoke damage than larger combatants.”

Unfortunately, both authors have interpreted the data differently, and some clarification is in order.

In analysis of survivability, it is important to look at three facets as defined by the US Navy:

  • susceptibility, the capability of the ship to avoid and/or defeat an attack;
  • vulnerability, the capability of the ship to withstand initial damage effects and to continue to perform assigned primary missions;
  • recoverability,  the capability of the ship, after initial damage effects, to take emergency action to contain and control damage, prevent loss of a damaged ship, and restore primary mission capabilities.

The data from World War II damage reports, along with an understanding of the US Navy inventory at the time, allows us to calculate a value for overall susceptibility of the various ship types during the war.  The damage reports also allow us to measure the combined vulnerability and recoverability of those ships that reported significant damage.

Hill calculated an overall measure of survivability based on the number of each ship type existing at the beginning of the war, which Hodges correctly notes is an insufficient baseline due to additional production during the war.  By using data from Table I of the damage summary, he overstates the overall risk of loss in each type of ship.  I offer the following so that an accurate baseline can be used to inform future discussions of survivability.

In the area of susceptibility, the damage summary, combined with the available construction data, shows significant variability by ship type and year.   In the table below, total inventory of DD and larger combatants is shown for each year, in aggregate and by class, as well as the total of newly commissioned ships for that year.  The susceptibility is the number of damage reports (including lost) divided by the total number of ships available in that year.  This still overstates susceptibility a bit, since not all new ships were available for the entire year, but it still serves a useful purpose.

Note that the total of damage and loss reports, not ships damaged, is used below.  Thus the CV susceptibility of 125% is not really a mistake, but an artifact of the method.  In 1942, Enterprise filed three war damage reports, Saratoga two, and Yorktown one in addition to the losses of Lexington, Yorktown, Wasp and Hornet.

Year and Type Starting Inventory Newly Commissioned Total
1942 167 102 91 33.8%
BB 17 0 12 70.6%
CA 18 0 16 88.9%
CL 19 9 9 32.1%
CV 7 1 10 125.0%
CVE 5 14 0 0.0%
CVL 0 0 0 0.0%
DD 101 78 44 24.6%
1943 231 186 45 10.8%
BB 15 2 0 0.0%
CA 13 4 2 11.8%
CL 26 7 9 27.3%
CV 4 6 1 10.0%
CVE 19 25 1 2.3%
CVL 0 9 1 11.1%
DD 154 133 31 10.8%
1944 403 133 110 20.5%
BB 17 2 10 52.6%
CA 16 1 3 17.6%
CL 32 11 12 27.9%
CV 10 10 11 55.0%
CVE 43 33 12 15.8%
CVL 9 0 3 0%
DD 276 76 59 22.7%

The outcome of each damaging event recorded in the summary gives us an estimate of the vulnerability and recoverability for each ship type.  Here we see a clear relationship between size and ability to take punishment.  I’ve separated the traditional surface combatants from the carriers for clarity.

Type Damage Reports Loss Reports Total Probability of Loss | Given Damage
BB 20 2 22 9.1%
CA 15 6 21 28.6%
CL 27 3 30 10.0%
DD 87 47 134 35.1%
DE 9 7 16 43.8%
CV 18 4 22 18.2%
CVL 3 1 4 25.0%
CVE 9 4 13 30.8%

At the surface, there appears to be a disparity between CA and CL loss rates.   However, this is most likely a function of displacement rather than ship type, as all six of the CAs lost through 1944 were Treaty Cruisers of less than 10,000 tons.

In reviewing these data as it relates to LCS survivability, I think we have to be somewhat cautious.  The general trend, showing that smaller ships are generally more vulnerable to (or less recoverable from) significant damage, confirms Wills in part.  While smaller warships are indeed, less survivable, they are not unsurvivable.  Because of their large numbers and lesser value as a target, the small destroyers were damaged less frequently than the larger surface combatants.  They relied more heavily than their capital ship brothers on the susceptibility leg of the survivability triangle.  Damaging events that were survivable by bigger ships were often fatal to the destroyers, because the bigger ships were more resilient and possessed a deeper capability for damage control.

The same will be true in the US Navy fleet of the 2020s, where Arleigh Burke destroyers will be much more capable of taking a hit than Littoral Combat Ships.  No modern ship, and especially no small ship, will survive as an effective combatant in the event of a major damaging event, like a torpedo, mine, or cruise missile attack.  Even though the ship might not be a total loss, it will be out of action for significant period of time after that event.  Look no further than USS Chancellorsville if you believe otherwise.

Ken Adams is a former US Navy Surface Warfare Officer with experience in amphibious ships and staffs, a battleship tour in USS Iowa, and as a tactics instructor for the Royal Saudi Navy. He is currently an operations analyst for a large defense contractor, for whom he is not authorized to speak.

LCS Survivability Debate: What the Data Doesn’t Tell Us

“Facts are meaningless.  You can use facts to prove anything that’s even remotely true. Facts, schmacts.”  

-Homer Simpson, from Lisa the Skeptic

100617-N-1200S-914Both Steven Wills in his USNI Blog opinion piece and Chuck Hill in his response trot out some interesting numbers in support of diametrically opposed positions on the survivability of LCS.  According to Wills, the US Navy lost ships under 3400 tons at a much higher rate than larger vessels in WWII.  Hill looks at the numbers and comes to the opposite conclusion.  The debate reminds me of the recent statistical dustup over the Patriots’ propensity to fumble that has accompanied Deflategate.  And the numbers are just about as meaningful.

Wills asserts that the US Navy lost 71 destroyers and 11 destroyer escorts in WWII.  Hill makes that number to be 58 destroyers and 9 destroyer escorts.  From what I can tell, they’re both wrong.  Using the summary report for ship losses to enemy action from 17 October 1941-7 December 1944, the US Navy lost 134 destroyers and 16 destroyer escorts through December 1944.  I could not easily find numbers from December 1944 through the war’s end, but the fact that these figures do not include losses from the Battle of Okinawa suggest that the actual number of destroyer losses for the whole war was closer to 150.  Over the period of the report, the US Navy also lost 51 cruisers (CA and CL), 22 battleships, and 39 aircraft carriers (combining CV, CVL, and CVE losses).   

After citing the number of losses, Hill uses the fate of vessels in commission at the start of the war to extrapolate survivability statistics for all vessels.  Statistically, this is highly suspect.  As Hill points out, the US fleet at the start of the war included just 233 major surface combatants.  But between 1941 and 1945, the US built over 1,300 more major surface combatants, including 349 DD’s and 498 DE’s.  Those ships in commission at the start of the war are a non-random sample, since they would tend to be older, slower, and less likely to incorporate new weapons, sensors, and other technologies that could affect survivability, unless backfitted during the war.  The US had no DE’s in commission at the start of the war, further skewing the sample.  

The numbers in the two reports point out some of the challenges with getting accurate data: since the US had no DE’s in commission at the start of the war, all 16 DE losses should come from those commissioned 1941-1945.  But only 9 are annotated as “sunk” in the shipbuilding report.  Similarly, 32 of the 349 DD’s commissioned during the war are listed as “sunk,” which when added to Hill’s figure of 29 destroyers in commission at the start of the war that were sunk comes nowhere close to the figure of 134 destroyers lost (nor even to Wills’ figure of 71, although it is over Hill’s figure of 58).  But it doesn’t matter.

falklands warThe most significant figure in the WWII ship loss data is zero.  That’s the number of ships lost to anti-ship cruise missiles.  While it’s tempting to try to draw equivalencies between threats in WWII and threats today, the simple fact is that war at sea looks different today than it did then.  The Falklands campaign, in which the Royal Navy lost two ships (a 5,000 ton destroyer and a 15,000 ton logistic ship) to Exocet missiles, and another five vessels (one LCU, two Type 21 frigates of 3,290 tons, a destroyer of 5,000 tons, and an auxiliary of 6,000 tons) to aerial bombs, may provide a more relevant frame of reference.  British ship losses in the Falkland campaign totaled two of 15 frigates and two of 12 destroyers or larger.  While these numbers are helpful, it’s worth remembering the facts behind the data: the RN were limited in their mobility by the need to protect the landing force; the Argentinians were operating at the outer limits of their range, limiting the duration of engagements.  And with such a small sample, it’s risky to draw too-strong conclusions.  

The most significant contributor to ship survivability is not getting hit.  Hill argues that LCS will not be a priority target due to its small size and relative unimportance.  Such an argument depends on the presence of perceived higher-value targets to draw fire.  But the whole nature of the A2/AD problem is that it creates too much risk to put high-value targets under the threat umbrella.  If LCS is the only surface platform we’ve got in the fight, it will be the platform that the adversary targets.  (Worse, if LCS is heavily dependent on the proximity of vulnerable combat logistics force ships to stay in the fight, an adversary may not need to target LCS at all, choosing instead to sink the oilers, rendering LCS immobile and irrelevant.)

The debate about LCS survivability is important, especially as we look to up-arm the ships and give them more offensive punch.  And, given the program’s history of overly-optimistic estimates of cost and capability, I understand why analysts would prefer to “go to the data,” rather than relying on assurances of improved survivability and defensive capability.  But unfortunately, we don’t have access to survivability data in an unclassified debate.  In the absence of the models and simulations that have been run on LCS versus modern threats, looking for examples from the past of different ship types versus different threats only clouds the picture.  In short, going back to World War II data to try to prove a point about the survivability of large ships versus small ships in modern combat is about as relevant as pointing out that USS Constitution, a ship of only 1,500 tons, was so survivable that she earned the name, “Old Ironsides.”  

Doyle Hodges is a retired Surface Warfare Officer currently pursuing PhD studies at Princeton’s Woodrow Wilson School of Public and International Affairs.