Admiral Yudo Margono, Indonesian Navy Chief of Staff, said the submarine had enough oxygen for 72 hours, based on calculations when the ship lost contact during a military exercise on Wednesday.
German-made KRI Nanggala-402 asked permission to dive or submerge at 3 am local time on Wednesday before losing contact, officials said. Margono said the submarine had just fired two torpedoes – one with live ammunition and the other with a training warhead – as part of the training exercises in the Bali Strait, a stretch of water between the islands of Java and Bali that connects to the Indian Ocean and the Bali Sea.
Answering questions about the submarine’s conditions before participating in the war simulation, Margono said that the KRI Nanggala-402 and his entire crew are well prepared. The last anchorage for maintenance was in 2020 in Surabaya, a port city on the island of Java, he said.
The military suspected that an oil spill seen in aerial surveillance near the dive site on Wednesday came from the ship. Margono said the Navy also found an object at a depth of 50-100 meters (approximately 164-328 feet) that was magnetic, meaning it probably came from the submarine.
Margono said there are two possibilities to explain the oil spill on the surface: the submarine’s tank may be leaking because it dived too deep, or the submarine released fluid on board in an attempt to rise to the surface.
Indonesian Navy spokesman First Admiral Julius Widjojono said the submarine has the ability to dive up to 500 meters (approximately 1,640 feet) below sea level, but authorities estimate it was 100-200 meters below that depth. .
Two ships equipped with side-scan sonar, a tool used to map the seabed, began researching the area on Wednesday, the Ministry of Defense said, while a Rigel warship equipped with sophisticated sonar that it can detect with Accurately the ship’s position is on its way to Jakarta, according to Widjojono.
The authorities hope that the crew is safe, but have acknowledged that the situation could be fatal at that depth.
“We will pray for them so that they can survive,” Widjojono told local media on Wednesday.
The International Submarine Escape and Rescue Liaison Office (ISMERLO), an organization that facilitates an international response to struggling submarines, is also providing assistance, the Ministry of Defense said.
The 1,395-ton KRI Nanggala-402 was built in 1977 by the German shipbuilding company Howaldtswerke-Deutsche Werft (HDW) and joined the Indonesian Navy in 1981, according to a ministry statement.
The submarine underwent a two-year renovation in South Korea that was completed in 2012, according to the Indonesian cabinet secretariat.
In the past, Indonesia operated a fleet of 12 submarines acquired from the Soviet Union to patrol the waters of its extensive archipelago. But it now has a fleet of just five, including two German-built Type 209 submarines and three newer South Korean ships.
Indonesia has been looking to upgrade its defense capabilities, but some of its equipment still in service is old and fatal accidents have occurred in recent years, in particular involving old military transport planes.
CNN’s Kara Fox contributed to this report.