China tests new version of world's largest amphibious aircraft as US interest in sea-going planes grows

• A new model of China's AG600 amphibious aircraft conducted its maiden flight on May 31.
• The AG600 is being developed for disaster response, but its amphibious capability has military implications.

An upgraded model of China's massive AG600 amphibious plane took its first flight on May 31, lifting off and landing at an airport in southern China's Guangdong Province.

The latest model of the AG600 brings a new configuration and a higher maximum takeoff weight to the world's largest amphibious aircraft.

Once fully operational, the AG600 would extend China's reach in the maritime-centric Pacific theater. The US military, which is increasing its own focus on Pacific operations, is also looking into developing aircraft with amphibious capability for similar uses.

Aviation Industry Corporation of China, the AG600's developer, said the aircraft performed several tests during its 20-minute maiden flight — including climbing at constant speed, reducing speed while at level altitude, and simulating a go-around after an aborted landing — and was in good condition with stable systems throughout, according to China's state-run Xinhua News Agency.

AVIC said the new model is specialized for firefighting, with a maximum takeoff weight of 60 metric tons and a capacity for 12 metric tons of water, in addition to a longer range. The firm said the AG600 would be able to serve in firefighting missions in 2023.

AVIC also installed a pressure cabin, fly-by-wire flight controls, integrated avionics, and other firefighting-related systems, according to China's CGTN, another state-run outlet.

That takeoff weight is an increase over the 53.5 metric tons listed for the original model, according to Flight Global, which noted other design changes, including a more rounded upper fuselage and more space under the plane's nose.

While AVIC and Chinese media have emphasized the AG600's emergency-response role, its size and amphibious capability have drawn attention to its potential military uses, such as combat search-and-rescue and carrying troops and supplies to far-flung bases.

The AG600 is one part of the "large aircraft family" that China is developing, which includes the Y-20, a long-range cargo plane that China's military has used in recent months to deliver humanitarian aid to Tonga and weapons to Serbia — both flights of several thousand miles.

The AG600 has "niche but important capabilities" and can "reach areas that otherwise are hard to get to," Timothy Heath, a senior international defense researcher at the RAND Corporation, told Insider in a 2021 interview.

"They can also support ships that are stranded at sea or just if it needs to connect with some ship at sea where there is no runway," Heath said at the time.

US amphibious efforts

The US military retired its last seaplane before the end of the Cold War, but its increasing focus on the Pacific and on a potential conflict with China have prompted renewed interest in amphibious aircraft.

Japan's military has long operated the highly capable US-2 amphibious aircraft, primarily for search and rescue, and US Air Force officials toured one in February at the Cope North 22 exercise, during which a US-2 participated in humanitarian assistance, disaster relief, and aerial-combat drills near the island of Tinian.

US Air Force Special Operations Command has already started a rapid prototyping effort to develop "a removable amphibious float modification" for its workhorse MC-130J.

The effort will allow the Air Force "to increase placement and access" and provide "enhanced logistical capabilities" at sea and near shore, the command said when the effort was announced last year.

This spring, the Defense Advanced Research Projects Agency issued a notice for its "Liberty Lifter" program, which aims to "design, build, and flight test an affordable, innovative, and disruptive seaplane" that can sustain ground-effect flight at altitudes less than 100 feet above the water and fly at altitudes up to 10,000 feet above sea level.

DARPA says it wants an aircraft that meets the Defense Department's heavy-lift requirement of over 100 tons and "that operates with runway and port independence."

Ground-effect craft, like the Soviets' ekranoplan, skim the water's surface, allowing them to reach high speeds.

While the ekranoplan's height ceiling limited what kind of seas it could operate in, DARPA wants the Liberty Lifter to be able to fly over waves as high as 18 feet, allowing it to operate in 85% to 90% of maritime conditions, the program's manager told Aviation Week.