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A top secret military acoustic detection system designed to spot enemy submarines first heard what the U.S. Navy suspected was the Titan submersible implosion hours after the submersible began its voyage, officials involved in the search said.
The Navy began listening for the Titan almost as soon as the sub lost communications, according to a U.S. defense official. Shortly after the submersible’s disappearance Sunday, the U.S. system detected what it suspected was the sound of an implosion near the debris site discovered Thursday and reported its findings to the Coast Guard commander on site, U.S. defense officials said.
While the Navy couldn’t say definitively the sound came from the Titan, the discovery played a role in narrowing the scope of the search for the vessel before its debris was discovered Thursday, the officials said.
“The U.S. Navy conducted an analysis of acoustic data and detected an anomaly consistent with an implosion or explosion in the general vicinity of where the Titan submersible was operating when communications were lost,” a senior U.S. Navy official told The Wall Street Journal in a statement. “While not definitive, this information was immediately shared with the Incident Commander to assist with the ongoing search and rescue mission.”
Officials decided “to continue our mission as a search and rescue and make every effort to save the lives on board,” the U.S. Navy statement said.
The Navy asked that the specific system used not be named, citing national security concerns. It is normally used to detect enemy submarines.
The U.S. Navy typically deals with foreign threats using military capabilities. The U.S. Coast Guard typically carries out search-and-rescue operations and handles other matters directly related to security of the country. The two services often operate together due to their mutual maritime missions. The search for the Titan was conducted roughly 900 miles off the coast of Massachusetts.
Searchers found debris from the submersible roughly 1,600 feet from the bow of the Titanic wreckage, the U.S. Coast Guard said. Canadian, U.S. and French ships were part of the search.
The Coast Guard didn’t immediately respond to requests for comment about what information it received and how it was used.
Throughout the search, rescue crews detected several types of noises, U.S. and Canadian officials said, including the one suspected of being the sub’s implosion. An underwater implosion is the sudden collapse of a submarine when the tremendous pressure of the seawater overpowers the pressure inside the vessel and crushes it.
Officials leading the search also said they heard sounds similar to knocking from the vessel, but said they couldn’t conclude the noises came from the Titan.
It was unclear what other factors narrowed the search area, which eventually grew to twice the size of Connecticut. But a U.S. defense official said “the analysis of the acoustic data was a significant factor in scoping the search area, and thereby enabling the assets on scene to locate the degree of the debris field.”
The U.S. is expected to conduct an investigation to try to determine whether the sound definitely came from the Titan, but what government entity would carry out the probe—and any time frame for completing it—remains unclear, a U.S. defense official said.
The U.S. developed its acoustic systems after World War II to detect enemy submarines operating in the Atlantic and Pacific Oceans.
The Navy said it shared its findings Sunday with the Coast Guard, which led the search, U.S. defense officials said. The U.S. held off making public what noises it had detected because it wanted to ensure search-and-rescue operations continued and couldn’t say for sure it was an implosion.
“It looks that the Titan imploded on Sunday on its way down to the Titanic shortly after contact was lost at a depth of around 9,000 feet,” a person with direct knowledge of the matter said.
The five men onboard the missing submersible in the North Atlantic are believed to be dead, the U.S. Coast Guard and the company that operated the vessel said Thursday.
The sub’s disappearance had set off an urgent international search effort to find its occupants alive.
The families were informed Thursday of the Navy’s findings when the search-and-rescue team discovered the debris field, according to a U.S. defense official.
The submersible had departed Sunday for what was supposed to be an hourslong excursion to the Titanic shipwreck, more than 2 miles below the ocean’s surface. Shortly after the voyage began, the sub lost contact with the outside world.
Write to Ben Kesling at ben.kesling@wsj.com, Nancy A. Youssef at nancy.youssef@wsj.com, Gordon Lubold at gordon.lubold@wsj.com and Costas Paris at costas.paris@wsj.com