Indonesian Navy rules out human error, overloading as factors in submarine sinking 28 April 2021 by Ridzwan Rahmat The Indonesian Navy (Tentara Nasional Indonesia – Angkatan Laut: TNI-AL) has ruled out human error, and refuted suggestions that its doomed Cakra (Type 209/1300)-class diesel submarine (SSK) was carrying more personnel than the boat was designed for at the time of its disappearance. KRI Nanggala seen here during a sail pass off Surabaya in 2014. The boat was declared sunk in the Bali Sea on 25 April. (Alex Widojo/Anadolu Agency/Getty Images) The SSK, KRI Nanggala (402), was first reported as missing on 21 April while it was preparing for a training mission in the Bali Sea, and was discovered sunk at a depth of about 830 m four days later. All personnel onboard have been declared by the TNI-AL as dead.