The missing Titanic submarine has tragically not been found as the deadline for oxygen running out on the submersible has now passed without any breakthrough in the search.
A desperate international mission was underway to try and find the five passengers stuck on the Titan vessel before the four-day oxygen ran out.
A US coast guard spokesperson previously said it will run out at exactly 7.08am US time - 12.08pm in the UK - today.
The craft submerged Sunday morning, and its support vessel lost contact with it about an hour and 45 minutes later, according to the Coast Guard.
Rescue teams were frantically searching for Pakistani British-based businessman Shahzada Dawood and his 19-year-old son, Sulaiman Dawood, French submersible pilot Paul-Henry Nargeolet, and chief executive and founder of OceanGate Expeditions, Stockton Rush.
Follow updates throughout the day in our live blog
However, the Rear Admiral in charge of the search, John Mauger, of the US Coast Guard, has said the operation to find a missing submersible is "still an active search and rescue".
Asked if he believes the oxygen on board will have run out by now, Mr Mauger told Sky News: "We continue to keep the crew members and the families in our thoughts as we proceed with this search and rescue while we're cognisant of the time and we've factored in a lot of data and information into the search.
"This is still an active search and rescue at this point and we're using the equipment that we have on the bottom right now, the remote operated vehicles to expand our search capability, and then also to provide rescue capability as well."
The US Coast Guard said it was deploying two remotely operated vehicles, which is now on the seabed.
The French government-backed vessel is about to deploy its own ROV, Victor 6000, into the ocean, the Coast Guard said.
The Horizon Artic ship arrived at the site of Titanic wreckage last night after travelling 400 miles overnight across the Atlantic Ocean from St John's port on the eastern Canadian coast to help join the frantic search.
The ship arrived with heavy duty cables and it was reported to be the last major support vessel to arrive before the oxygen on the vessel runs out, according to the US Coast Guard.
The ship, which can carry up to 60 people, left at 10.24pm on Wednesday evening from St John's port and arrived eight and half hours later at the site of the Titanic wreckage.
The Horizon Arctic set off to become the last main vessel involved in the desperate mission after the Canadian P-3 aircraft had picked up "banging" noises to try and locate the origin of the noises after US Coast Guard confirmed it had heard the sounds on Tuesday night and into Wednesday.
The vessel was reported overdue about 435 miles south of St. John’s, Newfoundland, according to Canada’s Joint Rescue Coordination Centre in Halifax, Nova Scotia.
Three C-17 transport planes from the US military were used to move commercial submersible and support equipment from Buffalo, New York, to St. John’s, Newfoundland, to aid in the search, a spokesperson for US Air Mobility Command said.
The Canadian military said it provided a patrol aircraft and two surface ships, including one that specialises in dive medicine on Tuesday. It also dropped sonar buoys to listen for any sounds from the Titan.
The US Navy said in a statement Wednesday that it was sending a specialised salvage system that’s capable of hoisting “large, bulky and heavy undersea objects such as aircraft or small vessels.”
The US Coast Guard confirmed the French remotely operated vehicle (ROV) L’Atalante which has the capacity to lift Titan to the surface has been deployed.
In a tweet, the US Coast Guard wrote: “The French vessel L’Atalante has just deployed their ROV.”
Deep Energy, along with eight other vessels, were at the site which is 900 miles east of Cape Cod, Massachusetts and 370 miles of Newfoundland, Canada. At least 10,000 square miles had been searched.
Rear Admiral John Mauger revealed yesterday it was unclear if the banging came from the submersible, as the noise was the "focus" of the mission.
Mr Mauger revealed they "don't know the source of that noise" but have reported the data with the US Navy. However, an initial attempt to locate the submarine had “yielded negative results.”
A US Coast Guard official said the efforts to find the vessel remained a “search and rescue mission, 100 percent.”
According to Dr Simon Boxall, who teaches oceanography at the University of Southampton, there are "so many variables" in terms of how long the oxygen could last.
He told NBC News: "There are so many variables. We have no idea how long they will actually last in terms of oxygen — all that we know is that it's imminent.
"It's not like" at 7.08 a.m. the rescuers will "pack up their bags and say, 'Right, we'll do a recovery operation, but we're taking the urgency off," he said. "They will still see this as being very urgent for next couple of days."
Former Royal Navy submarine captain Ryan Ramsey described the current situation as "bleak" while the search-and-rescue operation continues for Titan after oxygen is thought to have run out aboard the submersible.
He told the PA news agency: "The outlook is bleak, that's the only word for it, as this tragic event unfolds and almost the closing stages of where this changes from rescue to a salvage mission.
"That doesn't mean to say that the current ships and forces deployed won't continue to keep looking.
"They won't stop for many days, I imagine, but the reality is if you base it off oxygen alone, then they're out of oxygen.
"Carbon dioxide is also a critical element to it as well as the cold. It would be a miracle if there were survivors from it."
The Titan was launched from an icebreaker that was hired by OceanGate and formerly operated by the Canadian Coast Guard.
The ship has ferried dozens of people and the submersible craft to the North Atlantic wreck site, where the Titan has made multiple dives.
Mr Ramsey suggested the search was hampered by delays in getting resources to the area where Titan is believed to have gone missing.
Referring to the Kursk submarine disaster which killed all 118 Russian crew, he said: “There has been a delay and this comes back to the Kursk in 2000. The reason that we were able to rapidly deploy within 24 hours to that site was because they rapidly deployed the equipment immediately and that didn’t happen on this occasion.
“They probably lost two or three days getting equipment or ships there.
“There will be a variety of reasons for that, I don’t think it’ll be because they were just sat there and didn’t want to do it, they might have been engaged in other activity and had to decouple from that and then detach to support.”
Mr Ramsey expects the search for the missing submersible Titan to carry on for weeks.
He said: “If you remember when MH370 went down, that search continued for weeks, so you could find that now they have all that equipment there, particularly the really deep submersibles that are capable of those deep depths.
“They may search the whole area for weeks to come just to finalise it and around the Titanic wreckage itself.”
A British submariner and equipment from a UK firm will help the search for the missing Titan submersible, Downing Street said.
A No 10 spokesman said: “At the request of US Coastguard the UK has embedded a Royal Navy submariner to assist the search and rescue effort for the missing submarine.
“That is a Lieutenant Commander Richard Kantharia.”
Lt Cmdr Kantharia “has significant knowledge of submarine warfare and dived operations and so he will obviously be bringing that experience to the search and rescue team”.
The officer was on exchange with the US Navy and has been seconded to the search and rescue team.
A British C-17 aircraft will transport “specialist commercial equipment” provided by Magellan to St John’s to assist with the search-and-rescue effort.
Downing Street said Lieutenant Commander Richard Kantharia would be part of the Titan rescue efforts “as long as is required”.
The experienced submariner is understood to have joined the US Coastguard mission on Tuesday evening in the US.
A spokesman for Prime Minister Rishi Sunak, asked whether the request for UK assistance should have come sooner, said: “We’ve always said we stand ready to provide any assistance required and that continues to be the case.
“The search and rescue efforts continue and we will look to support that in any way we can.”
Asked how long Lt Cmdr Kantharia would be “embedded” with the rescue efforts, the spokesman replied: “As long as is required.”
The No 10 official, asked whether Mr Sunak planned to speak to the families of the British people onboard the missing Titanic submersible, said the Prime Minister’s “thoughts remain with” them and that the Foreign Office is in “constant contact” with those affected.
