Thursday, February 7, 2013

Aircraft Carrier - Vulnerable?

One of the things that annoys me to no end is when something gets repeated to the point that it becomes accepted as fact without any basis for that acceptance.  An example is littoral, as we’ve discussed in a previous post.  The Navy repeated the statement that a specialized littoral combat vessel was needed so often that eventually the dialog and examination simply skipped over the question of whether a littoral vessel was actually needed and, instead, jumped to what the vessel should look like.

Well, there’s another example floating around of a statement being repeated until it’s almost become a truism and it’s that the aircraft carrier is too vulnerable to be survivable on the modern battlefield.  With absolutely no proof to back up the statement, it’s repeated as fact.  In fact, it’s gotten to the point that even many proponents of the carrier have begun to accept the premise by beginning their arguments with, “Well, sure, it’s vulnerable but …”.

As ComNavOps does with all naval matters, we’re going to examine this issue in more detail, look at facts, and apply logic to determine whether the carrier is vulnerable or not.

Examination starts with definitions.  In this case, vulnerable has one of two meanings:

  1. Vulnerable means that the ship is more susceptible to damage/destruction than other ships on a relative basis.  If there’s something about a carrier that makes it inherently more susceptible to damage/destruction than a destroyer or frigate or battleship than it would be considered vulnerable.  For example, a ship made out of aluminum would be more susceptible to damage/destruction than a ship made out of steel.  Another example would be a tanker which, due to the nature of its flammable cargo, would be more susceptible to damage/destruction than a ship carrying dry goods.
  2. Vulnerable means that the ship is inherently unable to defend itself with a reasonable expectation of success.

Let’s also dispense with any notion that a carrier, or battleship, or any ship, for that matter, is invulnerable.  Any ship can be sunk given the right circumstances.  The fact that a ship can be sunk does not make it inherently vulnerable by our definitions.

Let’s start by looking at the vulnerability of the carrier compared to other ships.  Capt. Wayne Hughes noted in his book (1,  p.157) that the number of equivalent thousand pound bombs (or, alternatively, the number of equivalent 21” torpedos) required to put a WWII warship out of action (or, alternatively, sunk) was a direct function of displacement with the larger warships requiring more equivalents.  It’s hardly surprising that the finding was that larger ships are less vulnerable.  That’s intuitively obvious.

Hughes goes on to cite a Brookings Institute study (1, p. 161) relating the number of hits required to put a ship out of action to the length of the ship.  The overall relationship determined that the vulnerability of modern ships to cruise missiles was such that an additional missile was required for every hundred feet of length beyond 300 feet.  Again, the larger the ship, the less vulnerable.  No surprise.

Additional studies have drawn similar conclusions.  I won’t bother citing them since this is a blog post, not a book.

The Tanker War in the mid ‘80s further demonstrated the resilience of large ships.  In fact, the US Navy, during its convoy operations, used the tactic of allowing tankers to lead the way for the escorts because the tankers were so much more resistant to damage from mines.

Thus, it’s clear that the larger the ship, the less vulnerable it is in terms of the number of hits, of whatever type, required to put it out of action or sink it.  The aircraft carrier, simply due to its size, is, therefore, far less vulnerable than other ships.

Larger warships have several characteristics that render them less vulnerable than smaller ships.  One aspect is the ability of a larger warship to absorb more damage due to the greater degree of compartmentation.  Fire and flooding is easier to contain and the amount of reserve buoyancy is much greater.  Another aspect is manning.  Manpower has repeatedly been shown to be the single most important factor in damage control.  From WWII up through modern examples such as the Stark, Roberts, or Cole, sufficient manpower has been the key element of successful damage control.  No ship has more manpower than a carrier.  Finally, carriers have more damage control equipment and resources than any other size ship.  Whether it’s fire mains, power, power routing, foam equipment, or whatever, a carrier simply has more of it.

USS Enterprise - Too Vulnerable?

Consider the actual examples of the Enterprise and Forrestal fires.  Enterprise suffered at least 18 explosions, mostly 500 lb bombs, and torrents of burning jet fuel and survived.  The Forrestal suffered at least nine 1000 lb bomb explosions plus burning fuel pouring through the flight deck into compartments below and survived.  These incidents clearly demonstrate that a carrier is a very tough ship to kill.

Ships are lost when one of two things happens.  First, the damage may be instantaneously greater than any damage control effort can deal with and the ship is quickly lost.  This is the catastrophic kill such as the Hood or Arizona during WWII.  The second, and far more common scenario, is progressive damage where the ship was in no immediate danger of sinking from the initial damage but the progressive rate of damage (spread of fire, secondary explosions over time, progressive flooding) was greater than the damage control efforts could keep up with.  Here is where manpower and systems redundancy is so important.

So far, we’ve examined passive aspects of vulnerability.  Now, let’s look at active aspects.  Remembering our second definition of vulnerability, a ship may be vulnerable if it has an unacceptable self-defense capability relative to its size, cost, and intended purpose.  An LCS, for example, has little self-defense capability while a Burke DDG has extensive capability. 

An aircraft carrier is the most heavily defended platform on earth with hundreds of Standard missiles, Aegis sensors and battle management systems, an air wing with fighters and E-2C/D Hawkeyes capable of providing layered defense out hundreds of miles, submarines, and multitudes of RAM and CIWS systems.  Remember, a carrier never operates alone.  It is constantly surrounded by Aegis equipped ships and submarines as part of itself.  Think of the Burkes, Ticos, and subs as remote, off-board sensors and weapons for the carrier.  A carrier group is the toughest nut to crack in the world.  Examined from that perspective, a carrier is the least vulnerable ship in the world (OK, one could argue that an SSBN is).

I stated earlier that any ship can be sunk if it can be found.  Well, isn’t a carrier vulnerable because it’s so big and, therefore, easy to find?  Only someone unfamiliar with naval operations would make that claim.  The ocean is an immensely huge area relative to the size of a carrier.  The carrier is a mere pinpoint on the ocean.  In terms of the likelihood of spotting a carrier at sea, the carrier is no more at risk than any other ship.  Further, there are two aspects to this.  One is finding a carrier and the other is generating a valid targeting solution.  For example, an enemy may “find” a carrier by detecting the radar emissions from the carrier’s Hawkeye but that merely indicates that a carrier is somewhere within a several thousand square mile area – hardly a targeting solution.  One of the purposes of the carrier’s layered defenses is to prevent an enemy from acquiring a targeting solution even if the carrier’s approximate location is known.  Now I know some of you think satellites have a near magical capability to see anything, anywhere, at any time.  And, if a specific location or target is precisely known, that’s true.  A satellite can look into your living room.  However, tasking a satellite with finding an unknown carrier somewhere on the ocean is a monumental task. 

The difficulties inherent in establishing a targeting solution lead us directly to the uninformed public’s greatest fear – the dreaded carrier killer missile.  Aghhh!!!  I’m sorry, I scared myself for a moment, there, but I’m OK now.  Granted, an anti-ship ballistic missile is, potentially, a formidable threat and represents a real danger to a carrier if it hits.  However, as we’ve just discussed, the ability to target a carrier several hundred to a thousand miles away (the range of a ballistic missile) is exceedingly difficult.  As an exercise, run through the math of the amount of movement a carrier group would achieve from the time it is spotted until a missile can actually appear overhead.  The area of uncertainty is immense.  Barring dumb luck, the missile isn’t going to find anything there.  The US Navy recognizes the difficulty inherent in this kind of long range targeting and is expending great efforts to make it manageable.  In other words, we can’t do it, currently, and neither can the Chinese.  The only way to make targeting work at this extreme range is to have continuous mid-course updates from a loitering sensor close enough to the carrier to clearly discriminate it from its surroundings and the entire carrier group is designed to prevent exactly that.

Finally, some claim the submarine threat is too great for modern carriers.  This, of all the arguments, may be the most reasonable.  Modern nuclear submarines are a serious threat.  The Navy has allowed their ASW capabilities to atrophy to an alarming extent and this does increase the vulnerability of the carrier, or any ship for that matter.  Fortunately, the Navy seems to finally be recognizing this and is beginning to reconstitute its ASW capability though with nowhere near enough emphasis.  While submarines are a serious threat, the Navy has operated fleet carriers in the face of a submarine threat since WWII and today is no different.  Further, only China possesses a credible submarine threat and that, just barely, for the time being.

And, last of all, let’s repeat …  Any ship can be sunk.  That fact does not negate the need for, or usefulness of, a ship.  The mere fact that a carrier can be sunk does not mean we should quit building them or that their time is over.  The Navy has a long, proud tradition of standing in harm’s way.  Risk is part of combat.  The benefits clearly outweigh the risks and the carrier is the least vulnerable ship in the world, as we’ve just demonstrated.

(1) Fleet Tactics and Coastal Combat, Capt. Wayne Hughes, Naval Institute Press, 2000.



  2. The aircraft carrier, like the tank, has been on the verge of obsolescence since WWII. Back then, it was said the carriers couldn't handle jet planes with their higher landing speeds. Or that atomic bombs would render them useless.

    In the 1960's anti-ship missiles were going to give upstart navies a huge edge; as the sinking of the Israeli destroyer Eilat in '67 purportedly demonstrated.

    In the 1970's the USSR launched RORSats and built recon Bear and Badger bombers that on paper would hunt down CVBGs in the middle of the ocean for coordinated cruise missile attacks (never mind that the USN often evaded the Soviets during peacetime exercises).

    Now the A2/AD effort again dooms carriers. Never mind that the Chinese have never tested their ASBM, nor have been able to locate, and track a CSG at sea for any length of time.

  3. I second Anons link.

    Carriers are no more vulnerable, individually, than other ships.
    However, they are far more vulnerable, collectively.

    They are a massive concentration of risk, a single well targeted strike could remove a third of US fighting power in the area.

    Or it could hit a destroyer, with almost no effect on the US fleet in the area.

    I'm pro carrier, but they are a point at which the US is very vulnerable.
    They are awesomely protected, but they are a point of failure that can cause mayhem if it.

    1. Just to precise, carriers are not vulnerable individually or collectively. What is vulnerable ("at risk" would be a better phrase) is the collective USN firepower concentrated in 10 carriers. That risk is balanced by the incredible defensive protection applied to the carrier as well as its own inherent combat toughness. War is risk. If we want a strong strike platform, we risk losing it. If we don't want risk we can build a bunch of LCSs but that won't get us any useful strike capability. It's all a risk-benefit balance.

      You realize that you're arguing against your own comment from the previous post? You suggested massive VLS barges with 500-20,000 missiles. Talk about risking an enormous amount of striking power in a single platform. Are you still in favor of that? If so, how do you reconcile that with thinking a carrier is too great a risk?

    2. "It's all a risk-benefit balance."
      In my view, the entire US navy (surface fleet) striking power is concentrated in just 10 ships (well, plus the amphibs)
      Its an acceptable risk, but still a risk.

    3. TrT, my bad in that I artificially limited my comments to the aviation portion of the Navy's strike power since the topic was the carriers. Naval aviation is concentrated in 10 ships. However, the rest of the Navy's strike capabiity in the form of Tomahawks are distributed among 80+ VLS Burkes and Ticos as well as numerous Tomahawk Los Angeles and Virginia class subs. So, the Navy's total strike is distributed among well over a hundred vessels. My apologies for the too narrow focus!

    4. Well we could recom. and rebuild the Iowa's. I've seen some rebuilds with almost 400 VLS cells if the aft turret is removed.

  4. No one can argue that four and a half acres of US sovereign soil parked just outside any nations territorial waters is a persuasive incentive in the US national interest... Given that Aircraft Carriers will generally have a life of fifty years, there's no doubt that they represent a very good, if very expensive investment for all but the most serious of wars...

    The most serious of wars are likely to involve tactical nuclear weapons, and aircraft carriers will be very inviting targets as there will be no chance of civilian casualties, minimising the possibility of escalation. To be useful at all, carriers would have to be forward deployed to within strike range of their targets, substantially reducing the area that a hostile nation would need to search. Although aircraft would be unlikely to pierce the layered defences of a carrier group, satellites or submarines could locate targets and relay the information.

    Passive Sonars don't work well in the vicinity of large surface warships charging around, especially at the speeds required to launch aircraft. The USN recently rented the Swedish SSK Gotland for two years during which time the Swedish crew managed to get some good 'close-ups' of the USS Reagan. Although a single torpedo hit is very unlikely to sink a large, it could easily prevent a carrier building up the requisite amount of speed to launch aircraft.

    Having said that, attacking a carrier group with torpedoes must be a very high risk proposition but just as US and British SSN's are armed with Tomahawks, Russian and Israeli, and presumably Chinese boats are armed with nuclear tipped missiles. These wouldn't even have to be detonated within the task group as a nuclear explosion even on the horizon would generate an EMP which would cripple the electronics of a task group, leaving it vulnerable to a second follow up strike.

    To summarize then, Carriers are the best possible vehicles for intimidating and fighting non-nuclear nations. They're far more effective than other modern naval vessels such as submarines and cruise missile armed cruisers, because they are far more flexible. That flexibility howevever is very costly as it involves sixty or seventy aircraft (far more than would be based upon any wartime airfield) and the five thousand or so crew needed to keep them functioning even without including the escorting half dozen or so state of the art cruisers and destroyers. In short they're just too expensive to be risked in a high tech war. In those circumstances SSN's and SSK's will be the Queens of the sea, and not Aircraft carriers.

    BWC Feb 2013

    1. Here are a few points to consider relating to your comment.

      Carriers no longer need wind over the deck to launch planes. Planes can be launched at anchor though wind increases the safety margin.

      I have absolutely no idea what response the national command would make to an enemy's use of tactical nuclear weapons against our carriers (or any target, for that matter). That said, I would assume that the response would be the use of our own nuclear weapons against the enemy homeland since no potential enemy has worthwhile naval targets that could be retaliated against on a tit-for-tat basis. That's why we have SSBNs, so that no one attempts to engage us in "limited" nuclear war.

      You're correct that carriers are vulnerable to nuclear weapons, as are land bases, missile silos, cities, and everything else on Earth. The carrier's potential vulnerability to nuclear weapons is mitigated by the presumed assurance of an overwhelming nuclear response. Hence, I don't see carriers as being too expensive to be risked in a major war.

      Your comment about subs playing a dominating role in a major war is quite valid. Modern subs are extremely powerful platforms. My post did not suggest otherwise nor did I suggest any relative ranking of carrier versus subs. Both will play their parts and, properly used, both will prove extremely effective.