A Japanese Seaplane Could Be the Difference-Maker for the U.S. Military
On Jan. 23, 1992, a U.S. Air Force F-16 — Clan 33 — collided with its air refueling tanker during a ferry flight to the United States. The pilot ejected over the ocean some 625 miles east of Tokyo, well outside the unrefueled range of any rescue helicopters. No vessels were in place to rescue the downed pilot. Yet, just four hours later, Japanese forces found and saved the pilot. They didn’t use a ship or a helicopter. They used a seaplane, the aptly named Seagull 81.
During World War II, Japan, like most other nations with maritime operations, maintained a large and capable fleet of seaplanes. The United States lost interest, however. The U.S. military gave up its seaplanes for four reasons: First, World War II ended with a network of long runways in Europe, Asia, and elsewhere. This made the seaplane’s ability to land on water seem less relevant. Second, the “next generation” of seaplanes, the R3Y Tradewind and P6M Seamaster, both ran into development problems. Third, the U.S. Navy, faced with a shrinking budget, chose to prioritize carriers and ballistic missile submarines over other platforms and missions. Fourth, and finally, without Navy funding, no other service was going to fund seaplane development from scratch. The last American military seaplane flight took place in 1967, although the Coast Guard used them until 1983.
Yet Japan’s interest continued. In 1966, as the United States was winding down its own seaplane operations, Japan awarded Shin Maywa a contract to develop a military seaplane. That contract resulted in the highly capable US-1 seaplane. Today, Japan continues to operate an updated version of this seaplane, the US-2.
As the United States increasingly focuses on competition in the Indo-Pacific, and as elements of the U.S. military look specifically to amphibious aircraft, it would do well to consider acquiring these handy Japanese seaplanes. The US-2 is a proven and in-production design that would enhance joint capabilities from day one. Further, buying a small number of US-2s would allow the U.S. military to experiment with seaplane operations at a relatively low cost, with little to no research or development required. Finally, buying from a Japanese aircraft company would help strengthen the U.S.-Japanese alliance and highlight the bi-directional benefits of the relationship.
The US-2 is a technological marvel. Featuring a top speed of over 300 miles per hour, a max gross takeoff weight of over 100,000 pounds, and an un-refueled range approaching 3,000 miles, the US-2 excels in its primary mission of search and rescue. With rescue operations in the North Pacific in mind from inception, the US-2 can operate in waves up to 10 feet high. This makes it capable of operations in the open ocean for more than 95 percent of the year. Open-water capability is one of the distinct advantages of a true seaplane over a float-equipped aircraft. Not only can the US-2 search, at range, for downed aircrew, but it can also land and recover them.
Figure 1: A Japanese US-2 seaplane in flight (image courtesy of Hangar B Productions).
Buying the US-2 would instantly improve the ability of US forces to conduct search and rescue operations in the Pacific. Figure 2 shows the relative coverage improvement of a US-2 over a HH-60W, the Air Force’s Blackhawk-derived rescue helicopter, or a V-22, the convertible helicopter-aircraft tilt-rotor in use by the joint force. While HH-60s do typically operate in tandem with HC-130s, C-130 transports specially manned and configured for the rescue mission, the pairing is not guaranteed. If the HC-130 suffers a malfunction or is otherwise unavailable, the HH-60 is limited to its own operational radius. US-2s, on the other hand, provide a self-contained rescue capability at range.
Figure 2: Map showing the relative range of a rescue helicopter versus the US-2 seaplane. Range circles are approximate. V-22 range based on MV-22 in ferry configuration with max internal fuel (auxiliary tanks). Note: its actual radius of operation is likely to be significantly smaller (approximately 500 miles unrefueled, in line with the HH-60).
Such a capability would come without any meaningful increase in cost. Operating costs could be expected to be on the approximately $12,000 per flight hour (estimate based on the JRM Mars and Be-200 used as firefighting tankers), in line with the combined $15,000 cost of operating a HC-130J ($6,000 per hour) and HH-60W ($9,000 per flight hour), and far lower than the V-22’s hourly cost of over $20,000 (numbers based on Defense Department reimbursement rates — an imperfect but directionally accurate metric). The per-unit cost of the US-2 could be expected to be under $150 million, driven that high largely due to the very low rate of production. The combined HC-130J Combat King and HH-60W Jolly Green II team, in comparison, currently costs approximately the same. While the nearly $100 million V-22 combines the attributes of both the HC-130 and HH-60, it also suffers from a relatively limited unrefueled range. For example, V-22s typically plan for a 500-mile unrefueled combat radius, well short of the US-2s 1,400-mile radius. While adding internal fuel tanks can extend the V-22s radius out to approximately 1,000 miles, they are not typically flown in this configuration, and the aircraft loses significant internal volume. While air-to-air refueling can extend the range of any appropriately equipped aircraft, this increases cost dramatically. Additionally, it requires the right tanker to be in the right place at the right time. Moreover, V-22 squadrons do not typically train for or support the combat search and rescue mission (they lack the specialized personnel of the rescue squadrons), although they can perform it if required. If the United States desires a self-contained open-ocean rescue capability at ranges exceeding 1,000 miles, it needs to strongly consider the seaplane.
While seaplanes are not cheap, choosing to not buy them could be an extremely expensive mistake. Currently, it costs approximately $6 million to train an F-16 pilot and approximately $10 million to train an F-35 or B-2 pilot. In a conflict with a peer adversary, aircraft will be lost, and pilots will eject over the sea. Besides the economic and moral reasons to recover pilots, there is also an effectiveness argument: Pilots will be more likely to press home their attacks knowing they have a good chance of rescue. Hence, it is important the United States make the effort to recover pilots from the open ocean in wartime.
As the American military and its allies contemplate combat air operations over the vast expanses of the Pacific, they should weigh the advantages of seaplane-facilitated combat search and rescue. It would be surprising to many whose lives were saved by seaplanes — among them Eddie Rickenbacker, George Gay, and countless others — that the United States flies no rescue seaplanes today. The US-2 could solve that problem.
Besides offering immediate enhancement of combat search and rescue capabilities, the US-2 offers a platform through which American forces can experiment with the unique attributes of seaplanes. Seaplanes are, as I wrote previously, no panacea. They have real limitations, as do all aircraft. But in a future conflict where runways are under attack, the ability to land on the ocean could be an extremely relevant capability. While Air Force Special Operations Command has begun efforts to build a float-equipped C-130, this will take time and money without any guarantee of success. The US-2 is here, today, and it works. Acquiring US-2s would allow the United States to begin to refine use cases and understand how best to employ — or not employ — seaplanes.
Seaplanes could help the U.S. military solve several challenges in the Indo-Pacific, particularly the problems inherent to distributed operations. While the US-2 was designed for search and rescue and maritime reconnaissance, it is not difficult to imagine other uses for the aircraft, such as logistics support to far-flung forces. Seaplanes like the US-2 could help insert forces in otherwise inaccessible locations, keep them supplied, and evacuate them if necessary. In one hypothetical scenario, US-2s could infiltrate an unmanned aerial vehicle team onto a forward island to provide targeting support for strike aircraft. Additionally, although the US-2 was not designed from the start for movement of significant cargo, modifications could conceivably allow it to help sustain larger combat forces.
Leaders might even consider converting the US-2 into an air-to-air refueling platform. These tankers could refuel from ships, pre-placed fuel bladders, other aircraft, or from airfields and fuel farms close to the sea. If runways were available, they could land there as well. The ability to stage tankers forward from the ultimate unimproved surface — the ocean — would allow strike aircraft and other forces to project power under contested conditions. Not all these modifications would need to happen immediately. Initially, and in the spirit of a minimum viable product, the US-2 could be equipped only to refuel probe equipped aircraft. Boom integration, while offering numerous benefits, would be a more difficult task.
Figure 3: A Navy US-2, painted in legacy colors, refueling a flight of Navy/Marine Corps F-35s (image courtesy of Hangar B Productions).
Consider, for example, a US-2 equipped with air refueling pods similar those carried by C-130s. The US-2 carries approximately 60,000 pounds of fuel. It could fly approximately 600 miles from a forward operating location, offload 30,000 pounds of fuel, and return to land. That’s double the MQ-25 Stingray’s projected offload. Moreover, the US-2 would achieve that without taking up hangar space on a carrier or needing a catapult. Put another way, a single US-2 would be able to extend the range of a flight of four F-35Cs by 40 percent or double the range of two V-22s.
Another potential application of the US-2 would be in a role like that of the HC-130 and MC-130 (the Air Force’s special operations C-130), supporting rescue missions and special operations forces. Leaders in the rescue community should analyze the addition of a team of US-2s and V-22s as part of the shift to operations in the Pacific. Here, the US-2 could be equipped with air-to-air refueling equipment, or simply act as a mothership for helicopters and other vehicles. The ability to land on water would — as Air Force Special Operations Command has outlined — add flexibility and provide joint force commanders with more options. One asymmetric capability offered by a seaplane would be to “loiter” on the surface of the water. With good weather conditions, it is not unreasonable to imagine a seaplane landing on a body of water, shutting down its engines, and waiting days to support or accomplish a mission while its crew lived aboard. Such a concept would place a premium on the greater seakeeping ability of a seaplane over a floatplane.
Figure 4: A hypothetical Air Force US-2, painted in low observable colors, used for supporting special operations forces (image courtesy of Hangar B Productions).
Finally, the US-2 could act an element of the Navy’s maritime reconnaissance and strike complex. While the P-8 brings many capabilities to the joint force, it’s fundamentally a modified airliner. It requires runways — and long ones at that — to operate. The US-2 could conceivably be fitted with hardpoints to carry weapons or dispensers to deploy sonobuoys for anti-submarine warfare. Such an idea is not without precedent. The US-2’s predecessor, the US-1, carried sonobuoys and torpedoes. It was also able to deploy a dipping sonar from its hull after landing on the ocean. Similar modifications to the US-2 could turn it into a lethal patrol aircraft, in turn providing the Navy with a highly survivable and adaptable capability.
The US-2 could also provide naval forces with an enhanced ability to service, deploy, and recover unmanned surface and unmanned underwater vehicles. Seaplanes such as the US-2 could fly to forward locations, land, deploy an underwater glider or other vehicle, and return weeks later to recover it, download data, and otherwise support operations. This could significantly reduce the transit time for those vehicles and in turn increase their time on station. Furthermore, the ability of naval forces to deploy these unmanned vehicles over greater areas, and move them with greater speed, would only add uncertainty to adversary planning.
Figure 5: A Navy patrol seaplane, painted in VP-40 colors, equipped with sonobuoys and other sensors (image courtesy of Hangar B Productions).
Outside of the operational and technical reasons to purchase US-2s, there is also the matter of diplomacy. Simply put, buying a Japanese designed and manufactured seaplane would further improve the U.S.-Japanese alliance. In 2020, for example, Japan had over $20 billion in active arms sales from the United States. The July 2020 decision to authorize a $23 billion request from Japan to procure F-35 fighters was the second largest foreign military sale ever authorized. These purchases directly support U.S. jobs and domestic imperatives.
Shin Maywa is a smaller company, and the Japanese military can only afford to order so many US-2 seaplanes (nine, in fact). An order by the United States would help to keep this unique industry in a good financial position and to support the Japanese economy. It is rare for a nation to have built up too much goodwill. Buying Japanese is also the only realistic option outside of indigenous development. Currently, only three other countries are building capable seaplanes: China, Canada, and Russia. Purchasing Russian or Chinese seaplanes is a political non-starter, and Canada’s seaplane is both much smaller than the US-2 and optimized for fire bombing. If the United States wants to buy a seaplane optimized for operations in the Pacific, it should buy the US-2. Lastly, buying Japanese would remind America’s allies that the United States has no monopoly on innovation: Capable systems are capable systems, regardless of origin.
Diplomacy through the prism of arms purchases is not novel. The recent AUKUS (Australia-United Kingdom-United States) submarine deal further highlighted the diplomatic power of sharing technology. It is not difficult to imagine a world with the US-2 as a component of an arms agreement between nations such as Japan, Indonesia, Malaysia, India, and the United States.
If positive diplomacy is not enough of an impetus, there is also the specter of competition with China. China’s new seaplane, the AG-600, provides both a military and diplomatic capability. For example, early reports about the aircraft indicated that both Malaysia and New Zealand had expressed interest in the capability. China could potentially use the aircraft as part of its own diplomatic efforts. Surely, the United States would prefer regional partners to use aircraft designed by allies as opposed to those designed by adversaries.
As the United States pursues domestic designs for amphibious aircraft, it would be wise to consider off-the-shelf solutions as well. Whether it be a platform for search and rescue, a tool for experimentation, or a symbol of America’s commitment to the U.S.-Japanese alliance, there are few downsides to purchasing small numbers of the US-2.
Practically, the United States military should take three actions in the near term. First, it should explore the cost of purchasing a relevant number of aircraft from Japan and compare that cost to ongoing development efforts. Second, it should determine — through various methods — the relative efficacy of purchasing aircraft like the US-2 compared to other proposed solutions. Third, the United States should conduct limited exchange programs with the Japan Maritime Self-Defense Force to acquire operational experience in amphibian operations prior to U.S. capabilities coming online. Even if the United States ultimately determines purchasing the US-2 does not make sense for whatever reason, it will still benefit from a better understanding of allied capabilities and amphibious aircraft capabilities writ large.
These steps by the U.S. military should simultaneously be combined with efforts by the State Department and other government agencies to identify areas of synergy. Where can the United States spend its finite defense dollars in ways that have disproportionate positive impact on its position in the Pacific? Purchasing US-2s might mean everything to a downed pilot or stranded reconnaissance team, but there’s also the reward of furthering the alliances crucial to preventing conflict in the first place.
David Alman is an officer and pilot in the Air National Guard. He holds a B.S./M.S. in aerospace engineering from the Georgia Institute of Technology. The views expressed here are his own and do not reflect those of his civilian employer, the U.S. Air Force, or the Department of Defense. The author has no financial interest in any seaplane development, although he admittedly would love to fly one. He is especially grateful to Adam Burch of Hangar B Productions for the artwork featured here.
Image: Hangar B Productions