After a Canadian aircraft with sonar capabilities detected underwater noises near the area where a submersible with five people aboard went missing during a dive to explore the wreck of the Titanic in the North Atlantic, more focused searches have so far turned up nothing.
Remotely operated vehicles were redirected to the area where the noise was identified, but as of Wednesday, the efforts have not been successful.
"Those ROV searches have yielded negative results but continue," the U.S. Coast Guard wrote on Twitter.
An advisor to OceanGate Expeditions, the company that owns and operates the missing 21-foot sub, described the sounds as "rhythmic tapping" that are "consistent with human sounds" of people tapping on a hull. The advisor requested anonymity because they weren't authorized to speak on the subject with the media.
The Coast Guard declined to comment on the specifics of the sounds. U.S. Navy experts are analyzing the sounds to understand their origin, officials said.
The Coast Guard's statement on Twitter came after Rolling Stone magazine reported that "banging" had been detected at 30-minute intervals within the area where the sub, called the Titan, disappeared Sunday. The report was based on internal emails from the U.S. Department of Homeland Security's National Operations Center that said a Canadian aircraft had detected the noise after deploying several "sonobuoys."
In an interview Wednesday with "CBS Mornings," Coast Guard Rear Adm. John W. Mauger said officials "don't know the source of [the] noise," but at least two remotely operated vehicles and a Canadian coast guard surface vessel with sonar capabilities are focusing on the area where the sounds were observed.
Three additional ships joined the search Wednesday, including one commercial ship and two ships with the Canadian coast guard, officials said. More vessels and additional underwater robots are also being dispatched to the scene.
Officials have said the search mission, in a remote area of the Atlantic, is "very complex" and requires expertise and specialized equipment. The U.S. Coast Guard, the U.S. Navy, the Canadian coast guard and OceanGate have established a unified command to lead the effort, which is receiving international assistance from countries including France and support from commercial vessels.
The crews have been racing against the clock, with the sub facing a dangerously low oxygen supply, and have searched a total of 10,000 square miles since the search began Sunday. It's estimated there is about a day's supply of oxygen remaining in the sub based on the initial air supply of 96 hours.
"As long as there is an opportunity for survival, we will continue to work with this broad unified command to bring every resource to bear on the search," Mauger said on "CBS Mornings."
The five people confirmed to be aboard are Stockton Rush, the chief executive of OceanGate who was the expedition's pilot; Hamish Harding, chairman of Action Aviation, a Dubai-based company dealing in aviation sales and acquisitions; Paul-Henry Nargeolet, a veteran and accomplished diver with more than 30 trips to the wreck site; and Pakistani businessman Shahzada Dawood and son Sulaiman. Harding and Nargeolet are both members of the Explorers Club, according to the professional society.
The sub was first reported missing Sunday, when it lost contact with the Canadian research vessel Polar Prince about 1 hour and 45 minutes into its dive Sunday morning, about 900 miles east of Cape Cod, Mass., the U.S. Coast Guard said.
OceanGate has been running expeditions with "citizen explorers" to the Titanic since 2021 on its Titan sub, according to its website. The trip can cost around $250,000.
But the company has long faced immense scrutiny from industry experts and its own employees about what they said is a failure to adhere to safety standards for the Titan and its Titanic expeditions.
The Manned Underwater Vehicles Committee at the Marine Technology Society, which advocates for marine technology and resources, wrote a private letter to Rush in 2018 calling on him to allow for third-party safety review of the Titan. The letter said the marketing for the Titan was "at minimum, misleading to the public and breaches an industry-wide professional code of conduct we all endeavor to uphold."
"Our apprehension is that the current experimental approach adopted by OceanGate could result in negative outcomes (from minor to catastrophic) that would have serious consequences for everyone in the industry," the letter stated.
William Kohnen, the chairman of the committee, told The Times that Rush's more cavalier style of innovation troubled industry leaders, who felt compelled to speak out. "OceanGate raised a number of eyebrows and was the subject of many conversations," Kohnen said.
That same year, David Lochridge, a former OceanGate employee, raised red flags about the Titan in litigation against the company, "particularly OceanGate's refusal to conduct critical, non-destructive testing of the experimental design of the hull." Lochridge, a submersible pilot hired to do quality and safety inspections, said he was terminated for coming forward. He said he disagreed with Rush's decision to "subject passengers to potential extreme danger in an experimental submersible."
OceanGate said in its own court papers that Lochridge did not accept information provided by a lead engineer on the vessel's safety. It also claimed that he filed a false report with the Occupational Safety and Health Administration and that he violated his contract by discussing the company's confidential information with outside parties.
The case was settled in 2018. Lochridge did not respond to a request for comment.
Times staff writer Jeremy Childs contributed to this report.
This story originally appeared in Los Angeles Times.