All-out search for Titanic submersible as hours of oxygen left

Oxygen on the missing Titanic submersible is expected to run out in hours, with rescue efforts to find the five people on board in full force overnight.
The vessel, named Titan, lost communication with tour operators on Sunday while about 700 kilometres south of St John's, Newfoundland, during a voyage to the Titanic shipwreck off the coast of Canada.
As of Wednesday afternoon, it was thought just 20 hours of oxygen remained in the vessel, meaning it would run out at some point on Thursday morning.
The 6.7-metre-long OceanGate Expeditions vessel, which has British billionaire adventurer Hamish Harding on board, reportedly had a 96-hour oxygen supply in case of emergencies.
Also in the undersea craft are UK-based businessman Shahzada Dawood, his son Suleman Dawood, and OceanGate's chief executive and founder Stockton Rush, reportedly with French submersible pilot Paul-Henri Nargeolet.
The US Coastguard has been leading an international rescue effort which was stepped up after underwater noises were heard on Tuesday and again on Wednesday. However, experts have been unable to determine the cause of the sound.
Former US Navy submarine commander, David Marquet, told the BBC the noises might not be coming from the submersible.
"I don't think the noise is them, it could just be natural sounds," he said.
"We're hearing noises and more ships are coming into the area, and then we're hearing more noises, and I don't think that's a coincidence."
One of the vessels sent to help search efforts is the French research vessel L'Atalante which carries a remotely operated vehicle (ROV), Victor 6000.
This ROV has the capacity to lift the Titan ship to the surface.
Mr Marquet said he remains hopeful rescuers will find the vessel with the introduction of the ROVs.
The area of the search has been expanded, with the surface search now about 26,000 square kilometres, and the sub-surface search about 4 kilometres deep.
The coastguard had five surface vessels searching for Titan on Wednesday and they expected there to be 10 by Thursday, captain Jamie Frederick said at a press conference on Wednesday.
He added: "What I can tell you is, we're searching in the area where the noises were detected, and we'll continue to do so and we hope that when we're able to get additional ROVs [remotely operated vehicles] which will be there in the morning, the intent will be to continue to search in those areas where the noises were detected, and if they're continuing to be detected, and then put additional ROVs down on the last known position where the search was originally taking place."
Asked whether the mission was changing to become a recovery search, he said: "This is a search and rescue mission 100%, we are smack dab in the middle of search and rescue and will continue to put every available asset that we have in an effort to find the Titan and the crew members."
Titan is believed to be about 1,450 km east and 640 km south of Newfoundland. It is unknown how deep the vessel is, with the seabed being around 3,800 metres from the surface.
Questions have been raised about the safety of the vessel after it emerged earlier in the week that a former employee of OceanGate had raised concerns over "safety and quality control issues regarding the Titan to OceanGate executive management."
David Lochridge, OceanGate's former director of marine operations, claimed in an August 2018 court document that he was wrongfully fired after flagging worries about the company's alleged "refusal to conduct critical, non-destructive testing of the experimental design".
On Wednesday Kathleen Cosnett, a cousin of Mr Harding, 58, told the Telegraph that OceanGate's eight-hour delay before contacting the authorities was "far too long."
She said: "It's very frightening. It took so long for them to get going to rescue them, it's far too long. I would have thought three hours would be the bare minimum."
Sean Leet, co-founder and chairman of Horizon Maritime Services, which owns the Polar Prince mothership from which Titan launched, defended the company at a separate press conference on Wednesday.
He said: "OceanGate runs an extremely safe operation.
"Our full focus right now is getting that submersible located and getting those people brought back safely."