A massive search and rescue effort for the missing submersible near the wreck of the Titanic is in a critical stage with just hours before its oxygen supply for the five people aboard is expected to run out on Thursday.
The submersible, named Titan, began its descent at 8:00 am on Sunday and had been due to resurface seven hours later, according to the US Coast Guard.
The 21-foot (6.5-meter) tourist craft lost communication with its mothership less than two hours into its trip to see the Titanic, which sits more than two miles (nearly four kilometers) below the surface of the North Atlantic.
Titan was carrying British billionaire Hamish Harding and Pakistani tycoon Shahzada Dawood and his son Suleman, who also have British citizenship.
Also on board is the company’s CEO, Stockton Rush, and a French submarine operator Paul-Henri Nargeolet, nicknamed “Mr Titanic” for his frequent dives at the site.
Ships and planes have scoured 10,000 square miles (around 20,000 square kilometers) of surface water — roughly the size of the US state of Massachusetts — for the vessel, which attempted to dive about 400 miles off the coast of Newfoundland, Canada.
After the noises were detected by a Canadian P-3 aircraft, rescuers relocated two remotely operated vehicles (ROV) that search under the water and one surface vessel with sonar capability.
While coast guard officials insisted they remained “hopeful,” with a surge of assets and experts joining the operation and sonar picking up unidentified underwater noises, the challenge of locating and recovering the crew alive appeared increasingly formidable.
Based on the sub’s capacity to hold up to 96 hours of emergency air, rescuers estimate that the passengers may run out of oxygen in the early hours of Thursday.
Organizers of the multinational response — which includes US and Canadian military planes, coast guard ships and teleguided robots — are focusing their efforts in the North Atlantic close to the underwater noises detected by sonar.
An additional Canadian vessel carrying a medical staff and a decompression chamber was en route to the area early Thursday, with Canadian media reporting it was not expected to arrive before midday.
The sounds raised hopes that the passengers on the small tourist craft are still alive, though experts have not been able to confirm their source.