Does the USN Navy Need Smaller Aircraft Carriers… for ASW?

The Japanese helicopter destroyer JS Hyuga (DDH-181) alongside the USS George Washington (CVN-73)

There has long been a sentiment among some that the fleet carriers of the United States Navy are simply too large, too expensive, and too few in number. Instead, they feel that the Navy should switch to building significantly smaller carriers. The official Navy response to this position is that the possibility has been studied many times and that for the same amount of money smaller carriers will result in a fleet with substantially less combat power. Personally, I am of the opinion that the official Navy position is the correct one and that the current large carriers are the superior option - but there may be an argument for a new class of small carriers focused on antisubmarine warfare.

Since World War II, the USN has taken a combined-arms approach to ASW, with submarines, aircraft, and surface ships working together to counter the threat. Of these, submarines are arguably the most effective. However, they are also by far the most expensive and come with their own unique tactical limitations. Aircraft posses great mobility and are not at risk of counterattack from submarines, but aircraft are unable to operate in bad weather and their time on station dwindles the further they must fly from their bases. The P-8 Poseidon for instance, has a 4 hour time on station when operating 1200nm from its base (a 10 hour mission in total), requiring 6 or more to keep 1 on station. Thus, while submarines and aircraft are in many ways the preferred options for dealing with hostile submarines, the surface fleet must continue to be capable of defending itself.

Although USN ships continue to carry powerful hull mounted sonars, ASROC, and surface-launched torpedoes, these systems are all outranged by the sensors and weapons on modern submarines and are little more than last ditch defenses. Instead, their key ASW systems are now their towed array sonars and embarked helicopters, as these allow hostile submarines to be detected and attacked without exposing the ships to counterattack. But here lies the problem - the USN can currently put very few helicopters to sea.

Today the Navy has 22 Ticonderoga-class cruisers, 1 Zumwalt-class destroyer, and 37 Flight IIA Arleigh Burke-class destroyers, each capable of embarking two helicopters. There are also 12 Littoral Combat Ships with a single helicopter each (although there are currently experiments to give their Firescout UAV’s an ASW capability). This gives a grand total of 132 helicopters that must be spread across 11 carrier groups, 9 amphibious groups, and an unknown number of logistics groups. Thus, each group would have fewer than 6 helicopters available - only enough to keep 1 operational at all times.

The Italian carrier Giuseppe Garibaldi (R551)

One can easily imagine a scenario in which this limited number of helicopters would force a surface group under attack by multiple submarines to engage the enemy with short-range weapons - likely suffering heavy losses in the process. It is for this reason that the Japanese Maritime Self Defense Force, which has long prioritized ASW, considers 8 helicopters the minimum for a surface group and has been pushing for even more. Assuming a total of 30 groups to be defended, 8 helicopters per group works out to 240 embarked helicopters. Aiming for 12 helicopters per group to provide margins for attrition and greater than expected wartime requirements (a historical constant) would require 360 embarked helicopters - almost three times what is currently possible.

Meeting this latter requirement through building more surface combatants would take 180 two-hangar destroyers and frigates - nearly twice the current fleet of 100 combatants, many of which are single-hangar or flight deck-only. Assuming FFG(X) will have two hangars (although the current requirements only specify one), reaching this number would require 6 destroyers and frigates to be built annually and would take until at least 2040 (assuming no currently active ships were retired before before then - a clear impossibility).

Another option would be to place the necessary helicopters on existing ships other than surface combatants in a sort of ASW Distributed Lethality. Under this plan the carriers, amphibious ships, and logistics force would all be given ASW helicopters. Together, the LPD, T-AOE, and T-AKE fleets have hangar space for 78 helicopters, bringing the total embarked to 210 and requiring the CVN, LHD, and LHA fleets to accomodate 150 additional helicopters, something that is perfectly possible. The problem is that in doing so, the Navy would severely degrade its underway replenishment and amphibious assault capabilities. Further, embarking the helicopters on capital ships and support ships rather than escorts limits tactical possibilities. These less capable vessels must be kept further from the threat, reducing the effectiveness of their helicopters. Additionally, they cannot be independently deployed to reinforce higher threat areas, escort non-naval convoys, or operate in secondary areas as they are either too valuable or too vulnerable.

This is where the small carriers enter the picture. A ship of 15,000 to 20,000 tons, similar to the Japanese Hyuga-class or the Italian Giuseppe Garibaldi-class, would be able to support 12-18 helicopters, allowing 13-19 of such ships to bring the fleet up to requirement for 360 embarked helicopters. Even with a reasonably capable ASW and AAW suites for self-defense, these small carriers should cost no more than a guided missile destroyer and likely less. Indeed, the budget for the FFG(X) program would probably suffice to procure the necessary number of small carriers.

The Japanese landing ship JS Shimokita (LST-4002)

At a price of around $1.5 billion each, these would clearly be escorts rather than capital ships and could be risked accordingly. This would allow for strategic and tactical flexibility, allowing the small carriers to be placed in harm’s way to maximize the effectiveness of their helicopters. Further, with their extensive aviation facilities these ships would almost certainly prove valuable in other areas, such as mine countermeasures, defending against the small boat threat, supporting special forces, conducting humanitarian operations, and providing general maritime surveillance. With their sizable hangars and flight decks they would also provide ideal candidates for operating the next generation of advanced VTOL aircraft, such as the manned V-280 Valor or unmanned V-247 Vigilant.

These small carriers would not be a replacement for the current carriers. Indeed, they would not even be a supplement to the current carriers. Instead they would act as aviation-centric escorts, reflecting the realities of modern naval warfare where aircraft are as important as guns and missiles. To emphasize this point it may even be wise to further follow the Japanese example and designate them as DDH Helicopter Destroyers. At a price of $1.5 billion each they would cost as much as the traditional escorts they would serve alongside and offer no promise of being cheap. They would also be far from revolutionary as numerous other navies have long operated similar vessels. However, small carriers of this type may be the only viable way for the Navy to fill a critical capability gap.