What We Know So Far about the Sunken Indonesian Submarine KRI Nanggala

KOMPAS.com - Indonesian authorities have confirmed that the KRI Nanggala 402 submarine has sunk and all 53 crew members have fallen.

There are unanswered questions about what caused the disaster. But with the submarine now located on the ocean floor, what happens next?

First of all, what do we know about the incident?

On Wednesday, the KRI Nanggala 402 submarine lost contact off the coast of Bali.
The submarine was conducting torpedo drills when it went missing.

The 53 on board included 49 crew, three torpedo gunners, and the commander of Indonesia's submarine fleet. Their oxygen supply was due to run out on Saturday morning.

An underwater robot photographed the lost submarine lying broken up in three separate pieces on the ocean floor, the Indonesian Navy chief of staff Admiral Yudo Margono said.
"The KRI Nanggala is divided into three parts, the hull of the ship, the stern of the ship, and the main parts are all separated, with the main part found cracked," he said.

It sank to a depth of 838 meters — far below the submarine's maximum operating depth of about 250 meters. "Down to 500 meters, the hull could recover from any deforming that would occur from the pressure, because submarines do compress and then expand again," Frank Owen, secretary of the Submarine Institute of Australia, told the ABC.

"But below that, it rapidly gets more and more deformed, and would never recover from it, until eventually the plates themselves apart, or they rupture."

Why did the submarine sink?

The cause is still unknown, but Admiral Margono said the initial analysis suggested it was due to "natural factors", rather than human error or technical problems.

"We have evaluated it from the beginning and we believe this is not a human error, but more due to natural factors," he said in Bali on Sunday, April 26, without elaborating on what those factors were.

Margono said he believed that there was no human negligence and that the submarine had "followed all procedures needed".

The navy previously said an electrical failure could have left the submarine unable to execute emergency procedures to resurface.

But Admiral Margono said on Sunday he wasn't sure about a possible black-out as the cause, because he said during the diving process all the lights were still on.

"This means that the power was not immediately lost when diving," he said.
However, he said to determine the exact cause, they will investigate the remaining parts of the submarine.