Rescuers make last desperate push as final hours of oxygen on missing Titanic submersible tick down

The race against time to find a submersible that disappeared on its way to the Titanic wreckage site entered a new phase of desperation on Thursday morning as the final hours of oxygen possibly left on board the tiny vessel ticked off the clock. 

Rescuers have rushed more ships and vessels to the site of the disappearance, hoping underwater sounds they detected for a second straight day might help narrow their search in the urgent, international mission. But the crew had only a four-day oxygen supply when the vessel, called the Titan, set off around 6 a.m. Sunday. 

Even those who expressed optimism warned that many obstacles remain: from pinpointing the vessel’s location, to reaching it with rescue equipment, to bringing it to the surface — assuming it’s still intact. And all that has to happen before the passengers’ oxygen supply runs out. 

The full area being searched was twice the size of Connecticut in waters as deep as 13,200 feet (4,020 meters). Captain Jamie Frederick of the First Coast Guard District said authorities were still holding out hope of saving the five passengers onboard.