The US ditched its last flying boats 38 years ago, but they could still help fill the gaps against China in the Pacific

Coast Guard HU-16E amphibious aircraft
US Coast Guard Grumman HU-16E Albatross amphibious aircraft at Otis Air Force Base in Massachusetts.

  • It’s been nearly 40 years since the US got rid of its last seaplane, an aircraft long seen as outdated.
  • Growing attention on the Indo-Pacific and on China, which is developing its own seaplane, have revived discussion about the utility of amphibious aircraft.
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March marked the 38th anniversary of the retirement of the last US military seaplane. That aircraft, an HU-16E Albatross flown by the Coast Guard, left service 16 years after the Navy retired its last seaplane.

Seaplanes played a vital role in World War II and had been considered essential for naval supremacy. Despite grand plans for them early in the Cold War, seaplanes soon fell out of favor. But recent developments in China have led some to reconsider their utility.

In July 2020, China conducted the first successful sea trial of the AG600 seaplane, also known as the “Kunlong.”

The AG600 – the largest seaplane in the world – took off from an airport in Shandong Province, landed in the ocean off Qingdao, skied on the water for four minutes, then took off and returned safely.

The massive seaplane could put attention back on a type of aircraft the US military has long seen as antiquated.

Essential tools

Consolidated PBY-5A Catalina flying boat
A Consolidated PBY-5A Catalina in flight.

Seaplanes were once essential tools for the Navy. Long before aircraft carriers dominated the seas, vessels known as seaplane tenders were the only way to successfully conduct long-range naval-aviation operations.

They could pick up seaplanes with their large cranes and maintain the aircraft just like a conventional carrier would. The US Navy’s first aircraft carrier, USS Langley, a former collier ship, was converted into a seaplane tender when dedicated aircraft carriers became available in the late 1920s.

Eventually, seaplanes could be launched from the decks of warships, and long-range models could conduct important missions like anti-submarine warfare, search and rescue, naval interdiction, and, most importantly, reconnaissance, since they were able to spot enemy fleets while they were still hundreds of miles from friendly forces.

Perhaps the most recognizable American seaplane is the PBY Catalina flying boat. Made by Consolidated Aircraft and adopted by the Navy in 1936, Catalinas helped locate the Japanese fleet at Midway, rescued thousands of downed airmen and stranded sailors, and sank more than 20 Axis submarines.

A British Catalina flown by an American pilot was even responsible for locating the German battleship Bismarck during the Royal Navy’s intense hunt for it in May 1941, seven months before the US entered the war.

Cold War plans

Navy seaplane tender Salisbury Sound Martin P5M-1 Marlin
US Navy seaplane tender USS Salisbury Sound with a Martin P5M-1 Marlin on a crane in San Diego Bay in 1957.

The role of seaplanes had diminished by the end of World War II.

Reduced Axis submarine fleets posed less of a threat, and numerous airbases on the multiple liberated islands in the Pacific allowed the US Navy to use long-range land-based aircraft carrying heavier payloads.

But the Navy didn’t intend to give up on seaplanes. In fact, in the early years of the Cold War, it wanted to create a Seaplane Strike Force with at least three models, in addition to other models already in service like the Martin P5M Marlin.

The Convair R3Y Tradewind, a transport flying boat adopted in 1956, had a maximum range of over 2,000 miles and was capable of carrying 100 troops or 24 tons of cargo. Its tanker version could refuel four Grumman F9F Cougars at once.

But the Tradewind had engine problems, and all 11 were retired in 1958.

Convair R3Y-2 Tradewind refueling Grumman F9F-8 Cougar
A US Navy Convair R3Y-2 Tradewind refueling four Grumman F9F-8 Cougar fighters in September 1956.

The F2Y Sea Dart, also made by Convair, was an ambitious attempt to create an amphibious delta-winged fighter jet.

Capable of speeds as fast as Mach 1 and armed with four 20 mm machine guns or multiple folding-fin rockets, the Sea Dart first flew in 1953 but was canceled in 1957 after a fatal accident.

Perhaps most impressive of all was the Martin P6M SeaMaster. Originally intended to carry nuclear weapons, it was a massive jet-powered seaplane capable of flying at subsonic speeds and traveling some 1,000 miles.

After the development of the Polaris submarine-launched ballistic missile, the SeaMaster was repurposed as a minelayer able to drop 30,000 pounds of ordnance and with an 800-mile range.

But ballistic-missile submarines and larger carriers made the Seaplane Strike Force less critical for the Navy, and the SeaMaster project was canceled in 1959.

The AG600

AVIC AG600 Kunlong floatplane
The AVIC AG600 Kunlong floatplane.

Although the US has retired its seaplanes, a number of countries still have them in their inventory.

Russia has started replacing its turboprop Beriev Be-12s with the jet-powered Be-200ES.

Japan, a nation with a long and proud seaplane tradition, operates one of the most advanced models in service, the ShinMaywa US-2, which held the record for world’s largest seaplane before the AG600.

The AG600 was designed by the Aviation Industry Corporation of China (AVIC), the same outfit behind most of the People’s Liberation Army Air Force’s aircraft – including its stealth fighter.

AVIC AG600 Kunlong floatplane
The AVIC AG600 Kunlong floatplane.

Development of the AG600 began in 2009, with construction starting in 2014. It was unveiled in 2016, and its maiden flight was in 2017. China expects to finalize and deliver it by 2022.

The seaplane is 120 feet long and has a wingspan of 127 feet. It is reportedly capable of carrying 50 passengers and reaching a top speed of 310 mph and a range of 2,800 miles.

The AG600 will be a multi-purpose aircraft expected to conduct search-and-rescue and transportation operations. It is also able to carry up to 12 tons of water and disperse it over 4,000 square meters to fight forest fires.

The AG600 would be particularly useful in the South China Sea, operating between the numerous fortified islands China has built in recent years.

A seaplane revival

Japan amphibious aircraft seaplane Iwakuni
A Japanese Maritime Self-Defense Force US-1A amphibious aircraft prepares for a water landing in Iwakuni, Japan, January 8, 2013.

China’s development of the AG600, as well as the US’s greater focus on the Indo-Pacific region and its many islands, have brought the benefits of seaplanes back into the limelight.

Since they operate on water, seaplanes do not have to worry about the destruction of their airfields or bases.

Whereas landing craft rely on bigger logistical vessels to reach their destinations, seaplanes with large carrying capacities could disembark large numbers of troops and perhaps even light vehicles directly onto beachheads if rapid deployments or reinforcements on islands are necessary.

As aerial refuelers, seaplanes could extend the range of carrier aircraft, freeing up valuable space and pilots aboard US aircraft carriers. Seaplanes’ ability to be refueled by ships or submarines at sea could also extend their own ranges.

There are of course trade-offs. Seaplanes have historically been outperformed by land and carrier-based aircraft, which are faster and more maneuverable. Seaplanes also aren’t likely to last long against enemy aircraft. Moreover, to get the most out of a seaplane force, the Navy would likely need seaplane tenders, of which it has none.

But with greater attention on the challenges of operating in the Indo-Pacific region, and with China’s renewed interest in the aircraft, there’s reason to give the practical and tactical applications of seaplanes more study.

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