Families of the missing passengers on board the Titanic submarine were given a glimmer of hope after it emerged "banging" noises were picked up by sonar devices.
Rescue teams have just hours left to find the Titan which has 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 in the vessel.
On Tuesday, the US Coast Guard confirmed it had heard banging noises on Tuesday night and into Wednesday after the Canadian P-3 aircraft picked up the sound as underwater operations were underway to try and locate the origin of the noises.
Three C-17 transport planes from the US military have been 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 noise was being detected every thirty minutes and then four hours later after additional sonar devices were sent to try and track where the sound was coming from.
It remains unclear if the banging came from the submersible, but the noise is now the "focus" of the mission, according to Rear Admiral John Mauger.
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”
The area of the North Atlantic where the Titan vanished Sunday is also prone to fog and stormy conditions, making it an extremely challenging environment to conduct a search-and-rescue mission, said Donald Murphy, an oceanographer who served as chief scientist of the Coast Guard’s International Ice Patrol.
Ex-Royal Navy Clearance Diver Ray Sinclair believes the vessel could be stuck in the wreckage of the Titanic.
He told the Daily Express US: “They have to find this very tiny submarine in this massive ocean. The chance of getting another vessel out to rescue them is fairly slim, especially the chance of finding one that can reach the depths this one can go down to.
“There’s a chance the submarine could be stuck in the Titanic wreckage and the current is moving it back and forth, making the noise.”
Captain Bobbie Schooly, a former US Navy diver, told CNN that the submersible is “going to be making sounds itself with the systems on board”.
She said: “Those sonar buoys are picking up, they’re very good and they’re detecting these noises.
“The hard part is finding the submersible. And once they find the submersible, there are all sorts of situations of how to get that submersible to the surface and rescue the crew.”
The full area being searched was twice the size of the U.S. state of Connecticut in waters as deep as 13,200 feet.
The former diver believes the crew inside is trying to get the attention of those searching for them, adding: “The crew are hopefully making noises as well.”
Captain Jamie Frederick of the First Coast Guard District said authorities were still holding out hope of saving the five passengers onboard.
“This is a search-and-rescue mission, 100%,” he said on Wednesday.
Retired Navy Capt. Carl Hartsfield, now the director of the Woods Hole Oceanographic Systems Laboratory, said the sounds have been described as “banging noises,” but he warned that search crews “have to put the whole picture together in context and they have to eliminate potential manmade sources other than the Titan.”
The report was encouraging to some experts because submarine crews unable to communicate with the surface are taught to bang on their submersible’s hull to be detected by sonar.
The US Navy said in a statement Wednesday that it was sending a specialized salvage system that’s capable of hoisting “large, bulky and heavy undersea objects such as aircraft or small vessels.”
