(CNN) — An Argentine navy submarine that’s been missing for nearly a week may soon run out of oxygen if it hasn’t surfaced, the country’s navy says — a scenario giving urgency to a multinational search for the vessel and its 44-member crew.
The navy lost contact with the ARA San Juan submarine on November 15, shortly after the vessel’s captain reported a failure in the battery system while the sub was submerged off Argentina’s South Atlantic coast, the military has said.
Ships and aircraft from at least seven nations have been scouring parts of the South Atlantic for the sub. On Tuesday, three vessels will move to an expanded search area, Argentine navy spokesman Enrique Balbi said.
“The search area is two times the size of Buenos Aires,” Balbi said.
A day earlier, the spokesman said the search had entered a critical phase because the ARA San Juan crew’s oxygen could run out by Wednesday in one of the worst-case scenarios.
Under normal circumstances, the vessel has sufficient fuel, water, oil and oxygen to operate for weeks without external help, Balbi said, and the vessel could “snorkel” — or raise a tube to the surface — “to charge batteries and draw fresh air for the crew.” The oxygen situation could be helped, even if the vessel bobs adrift on the surface with the hatch open.
But if the sub doesn’t surface, oxygen might last only seven days, Balbi said. The vessel was submerged when the navy last made contact with it, and Tuesday marks the sixth full day of its disappearance.
“This phase of search and rescue is critical,” Balbi said Monday. “This is why we are deploying all resources with high-tech sensors. We welcome the help we have received to find them.”
‘Short-circuit’ reported before disappearance
The submarine was traveling from a base in far southern Tierra del Fuego archipelago to its home base in Mar del Plata, a city hundreds of miles to the northeast, when the navy lost contact with it last week.
The sub’s last known location in the San Jorge Gulf, off southern Argentina’s Patagonia region, is nearly midway between the bases. The vessel had been due to arrive at its destination Sunday.
Shortly before the navy lost contact with the sub, the captain reported it had experienced a “short circuit,” Argentine navy spokesman Gabriel Galeazzi said.
The captain was told to “change course and return to Mar del Plata,” Galeazzi said.
This type of problem is considered routine, and the crew was reported safe, he added.
There was one more communication with the captain before the sub went missing, Galeazzi said. The navy did not give details of its content.
The San Juan is a German-built, 65-meter long (213-foot) TR-1700 submarine, powered by one electric and four diesel engines.
Approximations of oxygen in the vessel are complicated, said William Craig Reed, a former US Navy diver and submariner. “It’s dependent upon the last time they actually recharged their batteries, how long ago they refreshed the air, what’s inside the submarine,” Reed said.
Peter Layton, a visiting fellow at the Griffith Asia Institute at Australia’s Griffith University, offered a scenario similar to Balbi’s: If the vessel had sunk but was still intact, Layton said, the crew would have about a week to 10 days of oxygen.
If the hull is intact, it can withstand ocean depths up to about 600 meters, Layton said. If the vessel is resting on Argentina’s continental shelf, it is likely in waters shallower than this, but if it’s farther out into the Atlantic Ocean, it could be below its “crush depth” in which the hull buckles under pressure.
Ships and aircraft from Argentina, the United States, Uruguay, Brazil and other nations have been searching for the sub on the surface and underwater.
Earlier hopes that searchers may have heard communication attempts by the crew have not panned out, the military said.
For instance, noises that had been detected Monday initially were thought to be a possible distress signal from the crew. But later analysis determined the noises were not from the missing vessel, but instead might have been from the ocean or marine life, Balbi said.
The navy on Saturday reported seven communication attempts that were initially believed to originate from the San Juan. But officials later said those calls had not come from the missing sub.
Officials said Tuesday that search teams overnight spotted an inflated dinghy and white emergency flares. But the raft is a different model than what would be carried on the San Juan, and a white flare is not typically used by the crew. No other missing vessels have been reported in the area, Balbi said.