Rescue teams race against time for Indonesian submarine with 53 aboard

Indonesian navy ships searched Thursday for a submarine that likely sank too deep to retrieve, making survival chances for the 53 people on board slim. Authorities said oxygen in the submarine would run out by early Saturday.

Some experts fear submarine may be too deep to retrieve

Indonesian navy personnel are seen on the submarine KRI Nanggala-402 as they arrive in Surabaya, East Java province, Indonesia, in a 2012 photo. Officials are struggling to determine the vessel's exact location, and its depth. (M Risyal Hidayat/Antara Foto/Reuters)

Indonesian navy ships searched Thursday for a submarine that likely sank too deep to retrieve, making survival chances for the 53 people on board slim. Authorities said oxygen in the submarine would run out by early Saturday.

The diesel-powered KRI Nanggala-402 was participating in a training exercise Wednesday when it missed a scheduled reporting call. Officials reported an oil slick and the smell of diesel fuel near the starting position of its last dive, about 96 kilometres north of the resort island of Bali, though there was no conclusive evidence that they were linked to the submarine.

"Hopefully we can rescue them before the oxygen has run out" on Saturday, Indonesia's navy chief of staff, Admiral Yudo Margono, told reporters.

He said rescuers found an unidentified object with high magnetism at a depth of 50 to 100 metres and that officials hope it's the submarine.

The military said more than 20 navy ships, two submarines and five aircraft were searching the area where the submarine was last detected. A hydro-oceanographic survey ship equipped with underwater detection capabilities also was on its way to the site around the oil spills.

Margono said the oil slick may have been caused by a crack in the submarine's tank after it sank.

Neighbouring countries are rushing to join the complex operation.

In this photo taken from a maritime patrol aircraft, oil slicks are seen Thursday in the area where the search operation for the Nanggala is being conducted in the waters off Bali Island, Indonesia. (Eric Ireng/The Associated Press)

Rescue ships from Singapore and Malaysia are expected to arrive between Saturday and Monday. The Indonesian military said Australia, the United States, Germany, France, Russia, India and Turkey have also offered assistance. South Korea said it has also offered help.

Indonesia's navy said an electrical failure may have occurred during the dive, causing the submarine to lose control and become unable to undertake emergency procedures that would have allowed it to resurface. It was rehearsing for a missile-firing exercise on Thursday, which was eventually cancelled.

The navy believes the submarine sank to a depth of 600-700 metres, much deeper than its estimated collapse depth.

Ahn Guk-hyeon, an official from South Korea's Daewoo Shipbuilding and Marine Engineering, which refitted the vessel in 2009-2012, said the submarine would collapse if it goes deeper than around 200 metres because of pressure. He said his company upgraded much of the submarine's internal structures and systems but lacks recent information about the vessel.

Frank Owen, secretary of the Submarine Institute of Australia, also said the submarine could be at too great a depth for a rescue team to operate.

Indonesian navy ships arrive at the naval base in Banyuwangi, Indonesia, on Thursday, to join in the search. (AFP/Getty Images)

"Most rescue systems are really only rated to about 600 metres," he said. "They can go deeper than that because they will have a safety margin built into the design, but the pumps and other systems that are associated with that may not have the capacity to operate. So they can survive at that depth, but not necessarily operate."

Owen, a former submariner who developed an Australian submarine rescue system, said the Indonesian vessel was not fitted with a rescue seat around an escape hatch designed for underwater rescues. He said a rescue submarine would make a waterproof connection to a disabled submarine with a so-called skirt fitted over the rescue seat so that the hatch can be opened without the disabled submarine filling with water.

Owen said the submarine could be recovered from 500 metres without any damage but couldn't say if it would have imploded at 700 metres.

'Terrible tragedy'

Australian Defence Minister Peter Dutton called the incident "a terrible tragedy." Dutton told Sydney Radio 2GB that the fact that the submarine is "in a very deep part of waters" makes it "very difficult for the recovery or for location."

Indonesian President Joko Widodo pledged an all-out effort and asked all of the country's people to pray that the submarine and crew could be found.

A ship carrying members of the Royal Malaysian Navy departs to join the search on Thursday. Several nations have offered Indonesia help in the search. (Royal Malaysian Navy/Reuters)

"Our main priority is the safety of the 53 crew members," Widodo said in a televised address. "To the families of the crew members, I can understand your feelings and we are doing our best to save all of the crew members on board."

The German-built submarine, which has been in service in Indonesia since 1981, was carrying 49 crew members, its commander and three gunners, the Indonesian Defence Ministry said. It had been maintained and overhauled in Germany, Indonesia and South Korea.

Indonesia, the world's largest archipelago nation with more than 17,000 islands, has faced growing challenges to its maritime claims in recent years, including numerous incidents involving Chinese vessels near the Natuna islands.

Last year, President Widodo reaffirmed the country's sovereignty during a visit to the islands at the edge of the South China Sea, one of the busiest sea lanes where China is embroiled in territorial disputes with its smaller neighbours.

In November 2017, an Argentine submarine went missing with 44 crew members in the South Atlantic, almost a year before its wreckage was found at a depth of 800 metres. In 2019, a fire broke out on one of the Russian navy's deep-sea research submersibles, killing 14 sailors.