A Canadian plane with sonar capabilities looking for the Titan vessel picked up sounds and search teams are trying to find out where they came from, the US Coast Guard said in a post on Twitter.

Remotely operated vehicles used in the search are being relocated, while data from the aircraft that detected the noises have been shared with US Navy experts to feed into future searches, the Coast Guard said.

Every hour is critical. The Titan is designed to have an oxygen supply of as much as 96 hours in case of emergency. The crew likely had around 24 hours of breathable air as of 6 a.m. New York time Wednesday, having departed on the mission to explore the Titanic site on Sunday.

A mother ship on the surface lost all communications with the Titan about 1 hour and 45 minutes after it submerged.

The search and rescue effort has become a fast-paced international logistics operation. US and Canadian authorities are on the scene, about 900 nautical miles east of Cape Cod, Massachusetts. France has dispatched a vessel equipped with an underwater robot that can go as deep as the Titanic site.

Several privately-owned vessels, one with a decompression chamber and some with underwater search devices, are also preparing to join the recovery mission. OceanGate Expeditions, operator of Titan and the Titanic survey trip, is leading underwater search efforts because of its knowledge of the site.

Watch: What it’s like to dive to the Titanic wreck

Earlier, an international exploration club with members on board Titan said “likely signs of life” have been detected, raising hopes of a rescue.

Richard Garriott de Cayeux, president of the New York-based Explorers Club, said on Twitter that “data from the field” had given the club fresh hope.

“We understand that likely signs of life have been detected at the site,” he said in a statement on the social-media platform. “We await hopefully good news.”

De Cayeux didn’t specify what data he was referring to, or provide details about what the “signs of life” were.

Canadian P-3 aircraft detected underwater noises in the search area. As a result, ROV operations were relocated in an attempt to explore the origin of the noises. Those ROV searches have yielded negative results but continue. 1/2

— USCGNortheast (@USCGNortheast) June 21, 2023

The Explorers Club confirmed that members Hamish Harding, who is the founder of investment firm Action Group and an avid adventurer, and Frenchman Paul Henry Nargeolet are on board the vessel. The other three are OceanGate founder Stockton Rush, and Shahzada and Suleman Dawood, father and son in one of Pakistan’s most prominent families.

At a Tuesday news briefing in Boston, US Coast Guard Captain Jamie Frederick wouldn’t say whether there was enough time to retrieve the submersible — even if it was found immediately — before its air ran out. The primary task is locating the craft, though transferring salvage equipment to the search site is a priority, he said.

“If the sub is located, then the experts need to look at what is the best course of action for recovering” it, Frederick said.

Titan, a 6.7-meter-long craft made of carbon fiber and titanium, is designed to operate at a maximum depth of 4,000 meters (13,120 feet).

The Explorers Club said it is continuing to try to get approval for a specialist remotely-operated underwater vehicle owned by exploration company Magellan to join the Titan search. Magellan’s equipment can reach depths of up to 6,000 meters and has descended to the Titanic wreck several times, de Cayeux said.

“We believe they can provide invaluable assistance,” he said.

Magellan said in a statement on its website that it is “fully mobilized to help.” OceanGate asked Magellan to fly necessary equipment and crew to Newfoundland, Magellan said.