The Day When Japan Has A True Aircraft Carrier

(SEKAI NO KANSEN (JAPAN) 01 SEP 13) … Hiraku Katsuyama

TOKYO – It is a bit of an old story, but when I heard that the successor DDH Shirane and Kurama would be in the 20,000-ton class, I had hoped that they would at least be named Soryu or Hiryu. However, when Soryu was the name given to a submarine, my hopes for a Japanese aircraft carrier – a Hi no Maru aircraft carrier – were somewhat dashed.

But two and then four years later, the Maritime Self-Defense Force acquired two 20,000-ton helicopter carriers. When I was asked to write this article about how these helicopter carriers will be used, I thought the possibility of a “true aircraft carrier” was still a dream, but as someone who spent half his life as an MSDF officer, I thought it over and realized this is a theme that cannot be avoided and I accepted the offer to write this article.

MSDF and the Rationale for Possessing a Light Aircraft Carrier

  1. The “Y Committee”      members, who were passionate about rebuilding the Japanese navy and were      the “fathers” of the MSDF, gave concrete study to the establishment of the      Coastal Safety Force (established in 1952), the predecessor organization      of the MSDF, and also left an “Overview Draft Plan for the Armament of the      Navy and Air Force.” This plan recommended that in the future four      8,000-ton “defense aircraft carriers” should be built as the main force      for the navy.
  1. While the First      Defense Build-up Plan, which went into effect in 1957, was being      implemented, a proposal for building an anti-submarine aircraft carrier      (around 10,000 tons) was floated within the Defense Agency as a plan for      fiscal 1959 and beyond (then Defense Agency Director General Munenori      Akagi said to be very positive about the idea). However, the proposal was      never given concrete consideration due to political and economic reasons.
  1. In the first half of      the 1980s, in addition to the threat coming from the Soviet Union’s      Pacific Fleet’s SSN submarines, the “threat to our sea lanes and the US      aircraft carrier task forces” posed by missiles that could be fired from      Soviet Backfire bombers was also very serious. During the formulation of      the FY1986 Defense Build-up Plan, the acquisition of Aegis ships and light      aircraft carriers that could carry V/STOL aircraft was considered, but      further and deeper discussions about the aircraft carrier plan were never      held.

Among naval officials there has traditionally always been the feeling that the “navy should not have any functional shortcomings.” In recent years, in addition to that from submarines, the threat from anti-ship missiles has greatly increased, and operational plans have been incomplete because of the lack of capability to “destroy the missile launch platforms (aircraft, ships)” and to “neutralize air bases and missile launch sites (striking power).” Aircraft carriers are also indispensable for maintaining sea control of necessary maritime areas. The navy should not lack the capability to respond flexibly to changes in strategy and military operations. This recognition is the basis for the concepts mentioned in 1 and 2 above.

In realistic terms, from the start the MSDF would work jointly with the US Navy (Seventh Fleet) for maritime defense. Fire power would be supplied by the US carrier forces, while the MSDF would patrol Japan’s sea lanes and expel submarines, which are the greatest threat to US aircraft carrier task forces, from essential maritime zones. For this, the strengthening of the MSDF’s anti-submarine capabilities has been a priority area for Japan’s defense build-up.

As mentioned in 3 above, the threat of a missile attack by the Soviet navy’s Backfire bombers was a very serious one for the defense of Japan’s sea lanes. The so-called “off-shore air defense” became an important theme for Japan’s defense build-up.

At that time, in order to respond to these potential missile-launching aircraft, consideration was given to deploying Air Self-Defense Force fighter planes on Iwo Jima island and introducing Aegis-equipped vessels or light aircraft carriers, but I recall that discussion within the Defense Agency about aircraft carriers did not reach substantive levels. In the end, Aegis vessels that were equipped with anti-submarine capabilities were introduced, and even though the threat of air attacks was very high in sea areas, the emphasis was on carrying out anti-submarine operations. This was not a matter of just “off-shore air defense”; this emphasis on anti-submarine capabilities was very significant for joint US-Japan operations from the viewpoint of securing a situation in which US aircraft carrier task forces could operate in the waters surrounding Japan.

Changes in the Military Strategy Environment

In recent years, China’s ambitions in the western Pacific Ocean have become very evident. As far as can be known from news reports in the discussions between the US and the Chinese leaders at their summit this past June, President Xi Jinping’s unabashed comments were astonishing. As might be expected, President Barack Obama referred to the US-Japan alliance and appeared not to forget to deflate Xi’s remarks, but the problem is the Senkaku Islands. There, America’s basic stance is: “We recognize that Japan has administrative rights over the Senkakus, but as far as the dispute over sovereignty, we do not take an official position on which side has sovereignty, and we hope both sides will resolve the issue through discussion.”

The Soviet Union once made the Sea of Okhotsk its own sanctuary, and even developed a naval strategy to deny the US military access to the Sea of Japan. In order to realize their strategy, when the Soviets tested the United States by bolstering their Pacific fleet, the strategy also enveloped the entire Japanese archipelago, and the United States did not hesitate to strengthen its military capabilities in the region to counter this strategy.

The clear difference between China’s very unreasonable claims and actions, as well as its propaganda and psychological warfare, regarding the Senkaku Islands and the Soviet Union’s past ambitions is that China is very skillfully making it difficult for the United States to act.

Accordingly, if Chins should undertake military action in regards to the Senkaku Islands, Japan should be prepared to respond by its own force independently. What cannot be in error at such a time is Japan’s military control strategy. Recent discussion on the defense of outlying islands has become quite clamorous, but the actual defense of these islands will hinge on whether Japan can secure and maintain air and naval supremacy in the areas around the islands. As the lessons from the Pacific War showed, Japan’s military was unsuccessful in defending any of the remote islands when it lost air superiority and naval supremacy.

In order to defend the Senkaku Islands, which means deterring and preventing military action by an adversary against them, Japan must bolster its naval and air power and enhance their operational efficiency. It should be kept firmly in mind that it is likely that Chinese military action against the Senkakus would probably extend from Okinawa to the remote Yaeyama Island chain and Miyako Island. For China, the military significance of controlling these islands and the waters around them would be much greater than possessing the Senkaku Islands.

The ASDF has an air base that could carry out operations to secure air superiority around the Senkaku Islands in Naha, but it will be important also to utilize the airports on Miyako, Ishigaki, and Yonaguni islands, which are closer to the Senkakus. The problem is that these remote islands are more vulnerable to ballistic missile attacks than the main island of Okinawa, where the US military bases are located. An adversary could easily continue to destroy airports and other facilities on Miyako, Ishigaki, and other islands by mid-range ballistic missile attacks. Japan’s air power must be built up so that it can overcome this vulnerability. It should be clearly perceived here that if Japan has a maritime platform from which fighter planes can take off and land, this weakness can be overcome. In this connection, attention is being focused on the utilization of the 22DDH and the 24DDH helicopter carriers.

Possibilities for the 22DDH Light Aircraft Carrier

It is still assuming a lot that Japan will acquire a fifth-generation V/STOL fighter plane (from here, generally understood to mean the F-35B), but I will discuss the developmental possibilities for the 22DDH helicopter carrier with this assumption.

1. Putting the F-35B Into Operation Without Remodeling [the 22DDH]

The 22DDH would be able to serve as a takeoff and landing, as well as a holding, vessel for the F-35B. As for the number of planes, in addition to pilot rescue helicopters and a V/STOL AEW aircraft, and considering the placement of the aircraft moorings and the necessary work space, it is thought a 22DDH could hold ten or so F-35Bs.

The problem is the payload for the planes on board. In the case of aircraft operations with the 22DDH, compared with a large aircraft carrier or a light aircraft carrier equipped with a ski jump ramp and landing equipment (arresting gear), the 22DDH would be fairly constrained as far as its combat radius and the number of missiles it could carry. However, since these constraints could be mitigated by advancing close to the area of operations so that the planes could be utilized, even though the number of planes would be limited, if a high-performance fifth-generation fighter plane like the F-35B is part of the equation, the 22DDH could play a substantial and active role.

2. Equipping a Ski Jump Ramp

A 22DDH could be equipped with a simple-type ski jump ramp. One way would be to attach a truss-structure ski jump ramp near the bow of the vessel. Even though this would include reinforcing the ship’s hull, attaching a ramp would require relatively little construction work, time, and cost.

However, in this case, to ensure an adequate length of the runway for takeoffs, the standby area for the next plane to takeoff will have to be limited, which would lengthen the intervals between takeoffs. Moreover, since a ski jump at the ship’s bow will create air turbulence, the direction the vessel can take during landings will be constrained.

A truss-type ski jump ramp would be made on land in advance, requiring several months for the construction and attachment and costing under 100 million yen. (The construction period and costs are estimates taking into consideration the relationship with the ship’s hull; further research needs to be done on matters, such as the adding of ballast, related to maintaining the ship’s performance. The same holds for the option described below.)

One other option is to build a full-fledged ski jump ramp within the bow. In this case, the 22DDH would be able to carry out flight operations as a light aircraft carrier. However, if a ski jump ramp is built into the bow, the powerful bow sonar array, the “sales point” of the 22DDH, would face major problems.

The bow of the 22DDH’s hull allows for the sleek hull shape, which reduces water resistance to facilitate speed, and ensures the performance of the bow sonar. A full-fledged ski jump ramp weighs several hundred tons (possible at most 500 tons), and if such a ramp is added to the bow, the bow trim will be greatly increased, requiring around (at least) 1,000 tons of ballast in the rear of the vessel. If the vessel is to be actually sailed on the high seas, a number of problems will arise concerning the reinforcement of the hull and ensuring of ship speed, and detailed study will have to be carried out to determine if this is a realistic option. Moreover, the construction period for a remodeling of this nature would require around half a year and the cost would run over several hundred million yen.

By widening the bow of the 22DDH’s hull, the above-mentioned change in the trim can be constrained, and secondarily, more space will be created, improving the ship’s functions as a light aircraft carrier, but the bow sonar’s performance will be compromised, and some means will be necessary to ensure the required speed for the vessel. This remodeling would require around one year and a cost of over one billion yen.

The Path to a “True Aircraft Carrier”

There are other problems in trying to make a DDH ship into an aircraft carrier. My discussion up to now has been premised on the assumption that Japan will acquire the F-35B. However, if the MSDF independently acquires the F-35B with the aim of using it for operations with the 22DDH, there will be cost/benefit problems concerning pilot training and other matters. It stands to reason that the most desirable option is for the MSDF to use some of the fighter planes acquired by the ASDF. However, Japan has just decided to acquire the F-35A (deployed at ground air bases) as the successor to the ASDF’s F-4. Could the F-35B be utilized as the successor to the F-15? Britain will apparently use the F-35B as the fighter plane for both its air force and navy. Can Japan make a similar decision based on this flexible concept?

As mentioned above, remodeling the 22DDH, which is equipped with an ambitious anti-submarine warfare system that is expected to play a core role in such warfare, into an aircraft carrier faces major problems.

Will not it be possible to resolutely move to remodel the 22DDH into aircraft carrier specifications by moving the sonar to the hull and so on? But in such a case, it would mean again changing the force strength and system architecture itself of the MSDF, which is now being revamped based on a new concept of anti-submarine warfare. It would not be a simple matter.

Transforming the helicopter carrier into a “true” aircraft carrier would require resolving issues that reach across both the ASDF and the MSDF and problems impacting the entire MSDF’s system for anti-submarine warfare. In reality, this option would be fraught with considerable complications.

However, even if the 22DDH is commissioned into service in line with the current plan, it could still serve as a takeoff and landing and holding vessel for V/STOL fighter aircraft. In order for Japan to prepare itself to be able to deter and prevent independently attacks on the Nansei Islands, particularly the Senkaku, Miyako, and Yaeyama islands, adding the F-35B operational capability to a 22DDH-class vessel is very meaningful. Moreover, it is also possible.

At the same time, in the present process of the revision of the current National Defense Program Guidelines and the formulation of the next Mid-Term Defense Program, strong political leadership and a great change in the thinking of currently serving Defense Ministry and SDF officials regarding transforming the DDH into a true aircraft carrier are necessary.


With their increasing size and cost, MSDF ships will be used for around 40 years after they are commissioned. Accordingly, we must realize that the military situation regarding Japan could greatly change during that period, and Japan should build vessels that allow the possibility of major remodelings during the period of their service. At 20,000 tons, the 22DDH is a large vessel, and various considerations are being factored in for its activities for MOOTW, and in light of the recent changes in the military situation affecting Japan, many quarters are expecting the possibility of its development into a light aircraft carrier after it is commissioned. In the request for budgeting for the 22DDH, great emphasis has been put on building large Hyuga-class helicopter carriers, but it will be quite regrettable if there is inadequate discussion on remodeling the 22DDH into light aircraft carriers in the future.

China’s dream espoused by Xi Jinping is the worst nightmare for Japan. I strongly urge that in order to resolutely back up our diplomacy militarily, we must particularly build up our own naval and air power response capabilities to enable us to maintain and enhance the deterrence provided by the US-Japan alliance.

Hiraku Katsuyama is former admiral and Japan Maritime Self-Defense fleet commander.

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