Noises have been detected from the search area of the missing deep-sea vessel near the wreck site of the Titanic as those on board face a dwindling supply of oxygen.
The submersible, named Titan, lost communication with tour operators on Sunday while about 435 miles south of St John’s, Newfoundland, during a voyage to the shipwreck off the coast of Canada.
Titan has five people on board, including British billionaire adventurer Hamish Harding, and on Tuesday the US Coast Guard estimated the 6.7 metres (22ft) long OceanGate Expeditions vessel had just 40 hours of oxygen left.
The others on board are Shahzada Dawood, his son Suleman and OceanGate’s chief executive and founder Stockton Rush, reportedly together with French submersible pilot Paul-Henry Nargeolet.
The US Coast Guard on Wednesday morning said: “Canadian P-3 aircraft detected underwater noises in the search area. As a result, ROV (remote operating vehicles) operations were relocated in an attempt to explore the origin of the noises.
“Those ROV searches have yielded negative results but continue.
“Additionally, the data from the P-3 aircraft has been shared with our U.S. Navy experts for further analysis which will be considered in future search plans.”
The Explorers’ Club, of which Mr Harding is a founding member, shared an upbeat message on Wednesday morning.
President Richard Garriot de Cayeux said in a statement: “There is cause for hope, that based on data from the field, we understand that likely signs of life have been detected at the site.
“They precisely understand the experienced personnel and tech we can help deploy… We believe they are doing everything possible with all the resources they have.”
Mr Garriot de Cayeux said they are ready to provide the UK-based Magellan’s remotely operated vehicle (ROV) that is certified to travel as deep as 6,000 metres.
Meanwhile, US media outlet The Rolling Stone reported an internal US government memo said “banging” was detected by Canadian search aircraft in 30-minute intervals on Wednesday.
It is understood the King is being kept informed of the search efforts, as Shahzada Dawood is a long-time supporter of The Prince’s Trust International and The British Asian Trust, both of which are charities founded by Charles.
It comes as a former employee of OceanGate had raised concerns over “safety and quality control issues regarding the Titan to OceanGate executive management”, according to court filings.
David Lochridge, OceanGate’s former director of marine operations, claimed in the August 2018 court document he was wrongfully fired after flagging worries about the company’s alleged “refusal to conduct critical, non-destructive testing of the experimental design”.
After “issues of quality control” with Titan were raised, the filings say Mr Rush asked Mr Lochridge to conduct a “quality inspection” report on the vessel.
During this process, Lochridge “identified numerous issues that posed serious safety concerns” but he was allegedly “met with hostility and denial of access” to necessary documents before later being fired.
The document claims he became concerned about a “lack of non-destructive testing performed on the hull of the Titan”, and that he “stressed the potential danger to passengers of the Titan as the submersible reached extreme depths”.
In a November 2022 episode of his Unsung Science podcast, CBS journalist David Pogue interviewed Mr Rush ahead of going on a Titan expedition to the wreckage.
In the podcast, Mr Rush told him: “You know, at some point, safety is just pure waste.
“I mean, if you just want to be safe, don’t get out of bed, don’t get in your car, don’t do anything.
“At some point, you’re going to take some risk, and it really is a risk-reward question.
“I think I can do this just as safely by breaking the rules.”
Mr Pogue also said he had signed a waiver before going on the dive which allegedly said: “The experimental submersible vessel has not been approved or certified by any regulatory body” and that the trip could result in death.
OceanGate has been approached for comment.
On Tuesday David Mearns, a deep-sea shipwreck hunter who is friends with Mr Harding and Mr Nargeolet, said he had seen reports of “tapping” being heard in the water, which he said could indicate the passengers are alive.
He told Channel 4 News: “There’s some reports that I’ve just read from my own club, which is how I know Hamish, is that somebody today has heard some tapping.
“Now they’ve got sonar buoys out there, there may be some other hydrophones that the mothership the Polar Prince had in the water.
“It’s hard to imagine how they could have heard that but still, they are at least trying to operate or encourage the rescue efforts to continue on and to be redoubled on the fact that they’ve heard something which suggests that the men are alive in the submersible.”
On Tuesday, Captain Jamie Frederick of the US Coast Guard said a “unified command” of multiple agencies was formed on Monday to tackle the “very complex problem” of finding the missing submersible.
