The U.S. Navy extracted a F-35 jet fighter from 12,400 feet below the South China Sea

Stealth and sophisticated sensor and data fusion make the USAF F-35 the most advanced fighter aircraft in the world, and operators praised its performance on combat deployments for operations in Syria and Iraq. But high operational costs and shortages of parts and trained depot technicians continue to plague the program. Airman 1st Class Duncan Bevan

Earlier this year the U.S. Department of Defense suddenly faced the catastrophic prospect of forfeiting crucial defense technology to a rival when a military aircraft—packed with highly classified systems—vanished in the South China Sea. The disappearance of the single-engine stealth jet, an F-35C Joint Strike Fighter, triggered a major search-and-recovery effort by a little-known Navy organization that specializes in ocean retrieval. The mission was a high-stakes race to save a Pentagon crown jewel from the extreme depths, with their frigid temperatures and crushing pressure. And it shows why the Navy now wants its crack salvage team to be able to dive even deeper.

The fighter was attempting to land on the aircraft carrier USS Carl Vinson on January 24. But coming in, it slammed its underbelly on the edge of the ship, careened across the short runway and spun 180 degrees before falling—intact—over the edge and into the sea. The pilot ejected and was transported, along with two deck crew, to Manila for medical treatment. Video of the mishap was leaked online within days, along with a photograph of the stricken aircraft, which appeared to float evenly on the turquoise sea before sinking. The 34,800-pound plane went down quickly, its engine thrust suffocated by seawater. With its movement now dictated by deep ocean currents that flow in layers, the jet likely zigged and zagged as it descended more than two miles to the pitch-black bottom, where it remained at a Titanic-like depth of 12,400 feet.

The F-35C is a state-of-the-art machine with systems and components that U.S. taxpayers have invested $76 billion to develop over nearly two decades. It is pivotal to nearly all Pentagon war plans, as well as those of more than a dozen allies, including NATO nations, Japan and Australia. The loss of this aircraft was particularly dangerous because it was within the grasp of a nearby nation with significant deep-ocean prowess: China.

Tai Ming Chung, an expert on China’s military modernization, who works at the University of California, San Diego, says Beijing’s ability to develop stronger weapons relies heavily on absorbing foreign technology and know-how. “If China somehow gained access to the crashed F-35C,” Chung says, “this would represent a major technology coup and allow the Chinese military aviation industry to gain insights to support its indigenous FC-31 fifth-generation fighter aircraft program—that is heavily influenced by the F-35.”

Despite the sunken U.S. plane’s exact whereabouts being unknown, its legal status was unambiguous. “Under general international law, the aircraft is considered sovereign property of the United States,” says Steven Honigman, who was formerly Navy general counsel during the Clinton administration. The problem is that the letter of the law is no guarantee against skullduggery on the high seas, notes David Concannon, a maritime attorney and deep-sea explorer. In the real world, the F-35 would not be safe if “China wanted to pick it off the bottom before the United States could get to it,” Concannon says. “In international waters, it is kind of a no-man’s-land—and there’s no restriction against recovering it.”

Indeed, when the technological prize is big enough, the sovereign status of a sunken object is often conveniently overlooked. In 1974, for instance, the CIA pulled off a bold mission to recover a sunken Soviet submarine in the Pacific: the agency purpose-built a special ship, ostensibly for deep-sea mineral mining but actually to haul up the stricken vessel—and enrolled businessman and aviation enthusiast Howard Hughes to provide cover for the secret mission.

In 2022 the swim fin was on the other foot—and the importance of the technological treasure sitting on the seabed was gargantuan. The F-35 Joint Strike Fighter is the most expensive weapon system acquisition in history. The U.S. military alone plans to procure 2,456 F-35s at a cost of $322 billion, excluding research and development costs, over decades.

The lost F-35C remained at the bottom of sea for about five tense weeks before the U.S. Navy managed to locate the aircraft and haul it up.

“The F-35C recovery was a tremendous team effort,” says Capt. Jay Young, director of ocean engineering and head of an entity called Supervisor of Salvage and Diving (SUPSALV). “Our team that conducted the search and recovery of that F-35C executed that operation flawlessly.”

SUPSALV, a Navy organization formed in the wake of Japan’s devastating 1941 attack on Pearl Harbor, supports marine salvage operations, provides pollution abatement expertise and helps with underwater vessel repair. Within SUPSALV, a specialized team of 10 Navy sailors and civilians oversees about half a dozen ocean-floor object recovery missions each year at depths between 330 and 20,000 feet. They use a Navy-owned collection of deep-ocean salvage equipment—including a family of autonomous and remotely operated vehicles that, in tandem with a portable lift system, can pull up gear as large as a school bus. This machinery is maintained and operated under contract by a marine services company called Phoenix International, based in Largo, Md.

When assigned a salvage mission, Phoenix must contract with a commercial ship in the vicinity of the missing object. After the F-35C sank, Phoenix sprang into action and retained a commercial vessel called the Picasso. The company then has to bring specialized tools and experts to the scene; it takes time to transport Navy-owned salvage equipment from Maryland by truck or military air and find welders who can temporarily affix that equipment to a host ship’s main deck. As a result, this part of a salvage mission can take many weeks.

Once it was on the scene and operating under SUPSALV oversight, Phoenix began its hunt using the latitude and longitude coordinates taken by the Carl Vinson crew when the aircraft fell in water. An autonomous vehicle began surveying the area in what search and recovery experts call a “mowing the lawn” pattern of adjacent scans—a tactic that in March helped civilian searchers find explorer Ernest Shackleton’s ship Endurance, missing since 1915, deep beneath the waters of Antarctica. Young declined to provide more details of the F-35C mission. But he says that, once a search begins, the Navy can pinpoint a submerged asset within a 25-square-mile area in 24 hours. On March 2 a remotely operated vehicle called CURV-21 attached a hook to the newly found F-35C and lifted the sensitive salvage.

The total time between crash and recovery: 38 days and 37 nights. By traditional Navy standards, this would be considered a success. But in recent years, technology for moving through the deepest parts of the ocean has improved—including technology developed by China. That means equipment that could once remain at the bottom of the ocean for weeks and be considered out of reach will, in future, be more accessible to organizations other than SUPSALV.

“Mission success counts for a lot, and they were able to locate and recover the wreck at that very deep depth,” says Victor Vescovo, a record-setting civilian deep-sea explorer and former naval intelligence officer. “But if it happens again, or if it happens in even deeper water, would that [response time] be sufficient?”

This question is critical because, although about 98 percent of the world’s ocean is no deeper than 20,000 feet, the other 2 percent holds trenches that can plunge to 36,000 feet. These valleys, formed where tectonic plates have collided and created the inverse of a mountain range, have long enticed explorers. In 2019 Vescovo set the record for the deepest ocean dive when he piloted his personal submersible to 35,853 feet in the Mariana Trench near Guam. The following year China sent a crewed submersible, the Fendouzhe, to a point nearly as deep on a scouting mission that included prospecting for new mineral sources.

After these two dives, the U.S. Navy determined that it, too, now needed the ability to search and salvage in such trenches. In January 2021 a top admiral changed the salvage requirement to “full ocean depth.” The Navy provides few specific details about how it plans to achieve this goal, but spokesperson Alan Baribeau says SUPSALV will need to integrate several key technologies that will add an extra $700,000 per year to the $6-million budget of SUPSALV’s Deep Ocean program.

“It’s really just being prepared for the day when something goes down below 20,000 feet, and we want to be prepared to be able to recover” items from those depths, Young says. Investing in faster and deeper underwater response technology could help prevent a future scenario where other nations manage to beat the Navy to valuable lost equipment. “That could cause a very interesting incident on the high seas in the future,” Vescovo says. “How would we interact with countries that are claiming salvage rights over something that we believe is ours? Do you end up with some sort of conflict near the bottom of the ocean, wrestling for this wreckage and the very sensitive electronics and other things that people want to extract from it? It’s completely unknown territory.” scientificamerican.com