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.