Fears of oxygen running out in missing Indonesian submarine

Indonesian submarine KRI Alugoro searches for missing submarine KRI Nanggala during an exercise off Bali island on April 21. Photo: AP

The Indonesian submarine KRI Nanggala 402 lost contact after diving off the coast of Bali on April 21, and concerns are growing that the submarine may have sunk too deep to be reached and salvaged. President Joko Widodo has called on all Indonesians to pray for the safe return of the crew and ordered all-out efforts to locate the stricken vessel.

Two ships left a nearby port on the morning of April 23 to join the search. More than 20 naval vessels, two submarines and five aircraft were mobilized for the search on April 22, and more large-scale, simultaneous search operations are expected to be launched on April 23.

Rescue ships from Singapore and Malaysia are expected to be in the area from Saturday to Monday next week, and other countries have also offered assistance.

“Our main priority is the safety of the 53 crew members,” Widodo said in a televised address on April 22. “To the families of the crew members, I can understand how they feel at this time and we are doing our utmost to save the lives of all the sailors on board.”

The missing submarine is expected to run out of oxygen at around 3 a.m. on April 24, said Navy Admiral Yudo Margono.

The search has focused on an oil slick found near the site of the submarine's last dive. But there is no conclusive evidence that the oil slick came from the missing submarine.

Admiral Margono said the oil could have spilled from a crack in the submarine's fuel tank or the crew could have dumped oil and other fluids to lighten the ship and help it float.

There is an unidentified object with a high magnetic field at a depth of 50 to 100 meters, and officials hope it is the submarine they are looking for, Margono said.

The Indonesian Navy also believes the submarine sank to a depth of 600-700 meters, much deeper than the hull can withstand water pressure. According to estimates from a South Korean company that repaired the submarine between 2009 and 2012, the submarine could explode at a depth of 200 meters.

The cause of the submarine's sudden disappearance is still unknown. The Indonesian Navy said an electrical failure may have prevented the submarine from performing emergency procedures to surface.

Besides the rescue ships sent by Singapore and Malaysia, other offers of help have also come from Australia, the United States, Germany, France, Russia, India, Türkiye and South Korea.

Indonesian Navy hospital ship KRI Dr. Soeharso joins search for missing submarine. Photo: AP

Submarine accidents have historically had serious consequences. In 2000, the Russian nuclear submarine Kursk suffered an internal explosion and sank during exercises in the Barents Sea. Most of the 118 crew members died instantly, while 23 managed to reach the aft compartment but then suffocated.

In November 2017, an Argentine submarine went missing with 44 sailors in the South Atlantic. It was not until nearly a year later that the wreck was discovered at a depth of 800 meters.

But in 2005, seven crew members of a Russian mini-submarine were rescued after their vessel became entangled in fishing nets and cables in the Pacific Ocean for three days, with only six hours of oxygen left if it could not surface.

It is known that the KRI Nanggala 402 submarine that is currently missing was made in Germany, used by Indonesia since 1981 and was carrying 49 sailors, 3 gunners and a commander at the time of the accident.