The last contact came at 3 AM on Wednesday. Then the Indonesian Navy submarine disappeared deep in the dark waters off the island of Bali in the Pacific Ocean.
By evening, the Indonesian Ministry of Defense had found only one possible sign of the missing ship, which carried 53 people: a wide oil slick found in the area where the submarine began its dive north of Bali.
The oil spill could be evidence of the submarine’s distress through a crack in the hull, said First Admiral Julius Widjojono, a spokesman for the Indonesian Navy. Such cracking is highly uncommon, but can occur with a sudden change in pressure, marine experts said.
The submarine’s latest request, known as the KRI Nanggala-402, was permission to descend to a deeper part of the Bali Sea to fire torpedoes for naval training, First Admiral Widjojono said. The area includes valleys that are at least 1,900 to 2,300 feet deep (or about 600 to 700 meters).
The request was granted, but then contact with the submarine was lost.
Built in 1977 in Germany and refitted in 2012, the Nanggala was last “fully serviced” in May 2018, according to a defense expert, who did not want to be identified when speaking of internal naval intelligence.
The submarine, approximately 60 meters long and over 5 meters wide, was built for 34 crew members, according to specifications quoted by the Navy during a previous training session. It is not clear why the ship had more people on board during this torpedo exercise.
“The quality of the naval crew is beyond question, but the handling of this submarine may need to be rechecked,” said Connie Rahakundini Bakrie, a military analyst at the University of Indonesia. “I am concerned that there is a lack of maintenance of standard operating procedures.”
Two Indonesian naval vessels are using sonar to search for the missing ship, First Admiral Widjojono said. One of the ships was deployed earlier this year to search for the flight recorders of an Indonesian jet that crashed in January.
Navies from neighboring countries, such as Australia and Singapore, have been warned and will join the search in the coming days, the Indonesian Ministry of Defense said.
Indonesia, a country of thousands of inhabited islands, is the world’s largest archipelago nation. The navy is poorly funded, even though the country faces frequent raids from foreign fishing fleets and coast guards.
Submarine accidents are rare. In 2000, a Russian Navy submarine sank to the seabed after an explosion on board. All 118 people died after rescue teams took days to access the submarine, and the 23 sailors who survived the blast ran out of oxygen.
In 2017, an Argentine Navy submarine went missing with 44 people on board, after a suspected electrical failure. The wreckage was found a year later.
But miraculous rescues have taken place. In 2005, seven sailors aboard a small Russian Navy submarine trapped in a fishing net were freed just hours before they ran out of oxygen.
“My fingers cross that aid will come from Australia and other countries,” said Ms. Bakrie, the Indonesian military analyst, referring to the search for the missing Indonesian submarine. “I cross my fingers that the crew will survive it all.”