As the author of Red November, Spies of the Deep, and other submarine/military books, and as a former U.S. Navy Diver and submariner, I have access to “inside information” about the lost Indonesian submarine KRI Nanggala 402. The 1977-vintage German-built Cakra-class diesel submarine disappeared on Wednesday, April 21. It’s a smaller boat, only 195 feet long by 20 feet wide, with four diesel engines that recharge a bank of batteries to provide a few days of power while submerged. The sub then needs to come shallow to “snorkel” by running its engines to recharge batteries and ventilate the air.

The commander of the Indonesian National Armed Forces reported that the Nanggala had gone missing in waters about fifty nautical miles north of Bali. The Indonesian Navy verified that the sub requested permission to dive prior to test firing two Surface and Underwater Target (SUT) torpedoes. An hour later, the training task force commanding officer authorized the shots, and the Nanggala flooded its torpedo tubes. The Chief of Staff of the Indonesian Navy said the Nanggala fired both an unloaded practice and a live torpedo before contact was lost.

What might have happened to the Indonesian submarine that led to its demise? How is this incident similar to the loss of the Russia Kursk submarine in August 2000? The Indonesian navy relayed that the Nanggala may have had battery power issues after submerging in waters more than 2,000 feet deep, which exceeds the sub’s crush depth by 400 feet. Torpedo test firings can also be hazardous, as the Kursk disaster demonstrated.

The Nanggala had 53 people on board, including 49 crew members, three weapons specialists, and the sub’s commander, Lieutenant Colonel Heri Oktavian. The commander of 2nd Fleet Command submarine unit was the highest-ranking naval officer aboard, who was accompanied by an officer from the Weapons Materials and Electronics Service. The latter was aboard to observe the test firings of the 1967-built AEG SUT 264 torpedoes, which are 21-inch heavyweight wire-guided weapons of German design.

On April 25, three separate parts of the Nanggala were found and the entire crew of 53 was confirmed dead.

Until the evidence can be examined, we can’t know why the submarine was lost, but there are similarities to the Argentinian ARA San Juan and Russian Kursk disasters. Older model diesel submarines are plagued by propulsion system malfunctions, such as battery shorts, fires, and explosions. Similar to the Kursk, the Nanggala was conducting torpedo firing exercises, so a weapons malfunction may be an even more plausible scenario.

On August 12, 2000, the bow compartment on the Russian Kursk submarine exploded, killing most of the sub’s crew. The Russians claimed that during a test firing of an outdated Type 65 torpedo, an unstable propellant caused the initial explosion. They suggested that the torpedo was loaded into an unclean tube moments before the scheduled firing, and the irritants ignited the fuel. Any torpedoman, whether NATO or Russian, knows that torpedoes are loaded and ready in clean tubes hours before a test-firing. Also, two civilian experts from the Dagdizel military plant were in the torpedo room monitoring the exercise and would not have allowed an unstable weapon to be mishandled.

Several high-ranking officials aboard the Kursk and the target warship, the Peter the Great, observed the exercise. The two vessels were thirty miles apart. A Type 65 torpedo at top speed would have taken thirty minutes to reach the target and would have run out of fuel before arriving -- an event not likely to attract an audience of senior military personnel. Recent evidence reveals that the Kursk was not test firing an old Type 65 weapon, but rather a newer top-secret Shkval rocket torpedo. To observe the exercise, the USS Toledo spy sub snuck in close. The tragic events that unfolded were covered up by Russian and NATO officials for almost twenty years.

Interviews with numerous experts and officials have verified that a Shkval became lodged in the tube during the firing exercise. After the firing mechanism was triggered, the Shkval was programmed to light off the rocket engine. Unable to leave the tube, the torpedo blew off the aft torpedo tube door, and two minutes later, the fire ignited the fuel in other torpedoes and caused the second, catastrophic explosion. Interviews with submariners aboard the Toledo also intimate that a scrape or near-collision with the Kursk may have inadvertently caused the Shkval to become lodged in the tube.

The secondary explosion disintegrated the forward sections of the Kursk, but the aft compartments remained intact. Twenty-three crewmen awaited a rescue that never arrived. New evidence revealed by the dive teams involved in the rescue attempt show that the Russians, while using antiquated rescue vehicles, may have accidentally flooded the aft escape trunk on the Kursk, which led to the demise of the survivors.

If a practice torpedo became lodged in the tube of the Nanggala, or the weapon experienced a “hot run” where the propeller spun up before leaving the tube, or there was a malfunction with the tube or firing system, this could have resulted in serious flooding that sent the sub to the bottom. Regardless of the reason, the demise of any submarine is always catastrophic, and the loss of life is devastating to the families of the crew. For those of us in the submarine community, this tragedy ignites a host of nightmares, and our prayers go out to those who are suffering during this time of mourning.

William Craig Reed is the New York Times bestselling author of the award-winning book Red November and Spies of the Deep: The Untold Truth About the Most Terrifying Incident in Submarine Naval History and How Putin Used The Tragedy To Ignite a New Cold War. This book reveals shocking new evidence about what really happened to the Russian submarine Kursk, lost in August 2000, and why Presidents Putin and Clinton covered up the truth about the incident. Reed is a former U.S. Navy submariner and diver and co-founder of Us4Warriors.org, an award-winning veteran’s non-profit.

Image: US Navy

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