Indonesian military chiefs said Saturday that a scan located the missing Indonesian navy submarine KRI Nanggala 402 around 850m beneath the sea.
The submarine was carrying 53 crew members onboard when it lost contact during a dive off the coast of Bali on Wednesday.
Rescue teams have also recovered debris from the vessel, indicating it has sunk. Items recovered from the water include a grease bottle believed to be used to oil the periscope and prayer mats.
Oxygen supply on the submarine was expected to last only until early Saturday. Hope arose on Thursday when an Indonesian Naval ship detected a “high magnetic object” at about 100 meters below the sea surface. Previously oil slicks were spotted at different locations nearby.
Based on the results of an interim analysis by the Indonesian Navy, the crew members of KRI Nanggala 402 may have experienced a “black out” which caused the ship to go out of control and unable to carry out emergency procedures to come to the surface of the water so that it fell at a depth of 600-700 meters, the Indonesian MoD had said earlier.
The Navy estimated the submarine KRI Nanggala-402 was at a depth of 700 meters (2,297 feet) when it lost contact. The depth is beyond 500 meters limit of what is considered “safe” from a rescue perspective.
KRI Nanggala 402 is a German-made diesel-electric submarine which uses electric power supplied by its batteries when below the surface and utilizes its diesel engines to charge the batteries when sailing on the surface.
Beyond mentioning the “black out,” Indonesian officials have not said anything as to what may have caused the black out- or a sudden failure of its electrical systems. However, what is perplexing is why the emergency ballast tank that inflates when electrical systems fail and pushes the vessel to the surface did not work in this case.
The KRI Nanggala 402 (Type 209/1300) weighs 1,285 tons, and requires a supply of 4 x 120-cell lead acid batteries.
The submarine was scheduled to conduct live torpedo exercises when it sought permission to dive. It began to dive at 3:45 a.m. local time, and the last contact was established at 4:25 a.m. local time when the commander of the exercise was ready to give authorization to launch a torpedo.
Previous deadly submarine accidents
Among the worst was the 2000 sinking of Russia’s Kursk submarine in the Barents Sea. The vessel was on manoeuvres when it sank with the loss of all 118 aboard. An inquiry found a torpedo had exploded, detonating all the others. Most of its crew died instantly but some survived for several days before suffocating.
In 2003, 70 Chinese naval officers and crew were killed in an accident on a Ming-class submarine during exercises.
When a fire extinguishing system onboard Russian submarine was accidentally set off, 20 people inhaled poisonous gases and died, five years later.
In 2013, blasts ripped through the torpedo compartment of the Indian Navy’s INS Sindhurakshak submarine. Fifteen sailors and three officers were killed. A year later, INS Sindhuratna Kilo-class submarine had a fire detected on board when trials were being conducted which resulted in smoke leading to suffocation and death of two officers.
ARA San Juan, an Argentine submarine with 44 sailors aboard sank in 2017 after the crews reported an “electrical breakdown.” It was found a year and a day later.