Titanic: Search continues for submersible with British billionaire among five onboard

Hamish Harding is chairman of private plane firm Action Aviation, which said he is one of the mission specialists on the five-person OceanGate Expeditions vessel reported overdue on Sunday evening about 435 miles south of St John's, Newfoundland. A major search and rescue operation, which is being led by the US Coast Guard and involving military aircraft 900 miles east of Cape Cod, was continuing on Tuesday.

The US Coast Guard said the Canadian research vessel Polar Prince and 106 Rescue wing will continue to conduct surface searches while the US Coast Guard sent two C-130 flights to search for the missing submersible. Rear Admiral John W Mauger of the US Coast Guard said they are doing "everything" they can to find the submersible, saying it has one pilot and four mission specialists aboard with up to 96 hours of emergency oxygen on board. "We anticipate that there's somewhere between 70 to the full 96 hours at this point," he said on Monday. "It is a remote area and a challenge, but we are deploying all available assets to make sure we can locate the craft and rescue the people onboard," he said.

Mark Butler, managing director of Action Aviation, said: "There is still plenty of time to facilitate a rescue mission, there is equipment on board for survival in this event. We're all hoping and praying he comes back safe and sound."

Mr Harding holds three Guinness World Records, including the longest duration at full ocean depth by a crewed vessel when in March 2021, he and ocean explorer Victor Vescovo dived to the lowest depth of the Mariana Trench. In June 2022, he went into space on Blue Origin's New Shepard rocket. His cousin, Kathleen Cosnett, told The Daily Telegraph she saw Mr Harding as "daring" and "inquisitive", and that she was "devastated" to learn he was missing.

On social media at the weekend, he said he was "proud to finally announce" he would be aboard the mission to the wreck of the Titanic, the luxury ocean liner which hit an iceberg and sank in 1912, killing more than 1,500 people. The Explorer's Club, of which Mr Harding is a founding member of, shared the news of his disappearance on Instagram with club president Richard Garriot saying: "When I saw Hamish last week... his excitement about this expedition was palpable," he said. "I know he was looking forward to conducting research at the site. We all join in the fervent hope that the submersible is located as quickly as possible and the crew is safe."

OceanGate Expeditions said its focus was on those aboard the vessel and their families. "We are deeply thankful for the extensive assistance we have received from several government agencies and deep sea companies in our efforts to re-establish contact with the submersible," the company said in a statement. "We are working toward the safe return of the crew members."

A court document filed by OceanGate in the US in April states that the submersible, named Titan, can dive to 13,120ft "with a comfortable safety margin", Associated Press reported on Monday. Titan weighs 20,000lb, is made of "titanium and filament wound carbon fibre" and has proven to "withstand the enormous pressures of the deep ocean", OceanGate reportedly said. The submersible was taking part in OceanGate's third annual voyage to the monitor the decay of the ship's wreckage, following expeditions in 2021 and 2022.