The Indonesian defense ministry has reported the discovery of an oil slick near the dive location of an Indonesian Navy submarine that has gone missing. The oil spill was discovered by aerial surveillance at 7AM Wednesday local time, two and a half hours after contact with the KRI Nanggala and its crew of 53 was lost at 4:30AM. Two sonar-equipped Indonesian Navy vessels have since been deployed to the area to search for the submarine.
The KRI Nanggala had been conducting live-fire torpedo drills off the north coast of Bali when contact was lost. According to a statement by Indonesian Navy spokesman First Admiral Julius Widjojono, the KRI Nanggala had requested permission to dive to carry out torpedo launching drills at 3AM on Wednesday, but failed to check in afterwards. The frigates KRI Raden Eddy Martadinata and KRI I Gusti Ngurah Rai were dispatched alongside corvette KRI Diponegoro to the submarine’s last known location, but active sonar searches did not locate it.
First Admiral Julius Widjojono said that preliminary hypotheses suggested that the KRI Nanggala may have suffered a blackout during the dive, resulting in a loss of control and preventing emergency procedures from being carried out. This ultimately resulted in the submarine sinking to a depth between 600 to 700 meters, far beyond its maximum dive depth of 250 meters. The oil slick may have been the result of water pressure causing the submarine’s fuel tanks to fail, or a signal from the crew for help.
The KRI Rigel and KRI Spica oceanographic research ships have since been dispatched to the KRI Nanggala’s last known position, and are to use their side scanning sonars to search for the submarine. Several countries including Singapore, Australia and India have responded to the Indonesian government’s call for assistance through the International Submarine Escape and Rescue Liaison Office, with the Republic of Singapore Navy having dispatched its MV Swift Rescue submarine rescue ship, equipped with the Deep Search and Rescue Six deep-submergence rescue vehicle.
The KRI Nanggala is the lead ship of the Cakra class of diesel-electric attack submarines, with the Type 209/1300 submarine commissioned by the Indonesian Navy in 1981, after being ordered in 1977 and laid down the following year in West Germany. It had undergone an extensive two-year refit in South Korea that was completed in 2012. According to the Indonesian Navy, the crew of 53 is composed of 49 sailors and 4 passengers, with the passengers being 2nd Fleet Command submarine unit commander Colonel Harry Setyawan and three weapons specialists. The commanding officer of the KRI Nanggala at the time of its disappearance is Lieutenant Colonel Heri Oktavian, who had been in command of the submarine for just over a year.
Senior leaders have since moved to Bali to command the search, and a press conference is expected to be held on the island at 7:30AM Thursday local time.