ARA San Juan indictments, guilty or scapegoats

Bruce Rule has shared with me his assessment of press reports indicating that three Argentinian Naval officers would be indicted for the ARA San Juan tragedy. Rule, now officially retired, was the lead acoustic analyst at the US Office of Naval Intelligence for four decades. He analyzed acoustic data to accurately calculate the location and condition of the ARA SAN JUAN wreck and has identified the sequence of events that led to the loss of the SAN JUAN. And I believe that is important to share his qualified opinion in this article.

Rule notes that recent press reports - if accurate - indicate the Argentine Court investigating the loss of the SAN JUAN has indicted three naval officers in connection with the tragedy. With decades of experience analyzing submarine losses, including the identification and documentation of major erroneous conclusions by the U.S. Navy Courts of Inquiry investigating the losses of the USS THRESHER (SSN 593) in 1963 and the USS SCORPION (SSN 589) in 1968, and analysis of six other submarine loss events from 1968 to 2000, Rule concludes the Argentine Court may be misdirected in its approach to the SAN JUAN event. He compares the reported indictments to asserting that airport personnel who authorized the departure of a flight would be responsible if that flight crashed hours later because of pilot error.

Based on what is now known about the loss of the SAN JUAN, Rule also concludes that the explosion of hydrogen generated by the flooded batteries is the only satisfactory explanation for the tragedy. It is essentially impossible for any other event or series of events to have prevented the SAN JUAN crew from either blowing ballast to surface the submarine or releasing emergency radio signal buoys.

Physical tests confirm that the velocity of the high-temperature flame-front/pressure-pulse of a hydrogen explosion is about 1400m/s which would have killed the entire SAN JUAN crew in no more than 30 milliseconds, less than half the minimum time required for human recognition of an event. The crew of the SAN JUAN died before they became aware of any problem. There was no anxiety or pain; death was essentially instantaneous.

Rule also notes that the loss of the SAN JUAN is unusual among the other eight such events he has analyzed because the cause of the tragedy can be clearly identified from the messages sent by the ARA San Juan to its base. Those messages discuss flooding and electrical short-circuits in the forward battery compartment and state that the Commanding Officer will order the crew to submerge to 40m and send personnel into the affected compartment to assess the damage and the possibility of repair. These orders - coupled with U.S. experience that - as of 1968 - all submarine battery explosions due to hydrogen released by batteries that had come in contact with seawater happened while crew members were working in the battery space and were the potential source of static electricity sparks.

Rule concludes that had the SAN JUAN remained surfaced, ventilated all compartments to the maximum extent possible, and not sent personnel into the forward battery compartment, the SAN JUAN would not have been lost on 15 November 2017 because of a hydrogen explosion. That event allowed the SAN JUAN to slowly sink to a depth of 468m where it collapsed (imploded) at 1351 GMT in 35 milliseconds with a force equal to the explosion of 5216 kg of TNT. The estimated time of the hydrogen explosion is 1330 GMT, about one hour and 40 minutes after the SAN JUAN submerged, the period during which the hydrogen slowly built up to explosive levels or the time members of the crew entered the forward battery compartment.

He suggests the Court working to identify the cause of the tragedy concentrate on communications between the SAN JUAN and its base before considering actions involving personnel who were ashore when the tragedy occurred and very unlikely to have been responsible for the loss of the submarine on 15 November 2017 because of a hydrogen event.

Finally, Rule also suggests all navies that operate submarines with lead-acid batteries be certain their crews are aware of the potentially fatal risk associated with flooding of battery spaces and have developed procedures to reduce that risk.

Note: During an event strikingly similar to the loss of the ARA SAN JUAN, the GOLF-II Class Soviet ballistic missile diesel submarine K-129 was lost on 11 March 1968 while snorkeling in very heavy seas in the northwest Pacific. Three hydrogen explosions occurred in the aft battery compartment within a 49-second period. The conclusion that these explosions instantly killed the K-129 crew is based on the observation that the Soviets extensively searched a wide area of the northwest Pacific for almost two months with no success. Had any of the crew survived, a message reporting the position of the emergency should have been sent. The submarine was found a few months after its loss by the US Navy using a underwater acoustic sensors, far from its original estimated position and sunk at a depth of almost 5km.