The submarine reported to be missing is the KRI Nanggala-402 vessel, a German-built vessel in service of 1981 vintage.
An Indonesian Cakra (Type 209/1300) class diesel-electric submarine (SSK) has been reported to be missing near Bali. Indonesian Navy (also known as Tentar Nasional Indonesia-Angkatan Laut or TNI-AL) operated KRI Cakra (401) and the KRI Nanggala (402) since the early 1980’s decade. The submarine reported to be missing is the KRI Nanggala-402 vessel. The Nanggala is a German-built vessel in service of 1981 vintage.
What was the submarine doing?
According to reports, KRI Nanggala (402) had lost contact in the sea 95 km north of Bali on April 21, 2021 and had 53 crew members. It was conducting torpedo firing drills when the contact was lost in an area which was up to 700 meters deep in the sea.
SAR (Search & Rescue) Operations initiated by Indonesian Navy (TNI-AL)
Indonesia reached out to India, Singapore and Australia for help and they have sent their submarine rescue boats. Six warships of TNI-AL are already at the location to assist other warships to help in the rescue mission.
More about TNI-AL
Indonesia as a nation is not new to submarine operations and it had operated a fleet of ex-Soviet era submarines in the 1960s and 70s. As per the Navy’s areas of operations, there are three main Indonesian fleets with the Western fleet based at Jakarta, the Central Fleet at Makassar and the Eastern Fleet based at Sorong. As per the information available in the public domain, as part of its modernisation efforts it ordered Nagapasa (DSME 209/1400)-class diesel-electric submarine (SSK) in 2011. This March’2021, Indonesia took the delivery of the third and final class of the boat and this submarine was the first-ever SSK assembled indigenously under the Transfer of Technology (ToT) with South Korean shipbuilder Daewoo Shipbuilding and Marine Engineering (DSME).
SAR (Search & Rescue) Operations – How is it carried out? Know more about it
“It is very important that the search operations are as efficient as possible. A combined search operation using multiple ships and aircrafts speeds up this SAR process by covering the maximum search-area in a minimum time. Some of the visual signs which the search and rescue (SAR) team looks out for while searching for a distressed submarine are the oil spills or some floating debris nearby the last known location of the submarine,” explains Milind Kulshreshtha, a C4I expert, and Strategic Analyst.
According to him, “The SAR activity is a methodical process where the search patterns in water and from air are well defined to maximize the probability of location of the submarine. However, time is always critical when limited oxygen capacity exists onboard a distressed submarine, and some specialised searches which maximises the probability of detection in the shortest time too are useful. The naval vessels involved in the search operations use sophisticated sonars to scan the sea bottom to identify the submarine in the underwater profiles obtained on the displays. There is also a look out for any acoustic noise emanating from the machines of the submarine, if running, or emergency signal direction finding using passive means.”
Is Indian Navy equipped to handle such accidents?
As has been reported by Financial Express Online earlier, Indian Navy has procured a Deep Submergence Rescue Vessel (DSRV) to undertake submarine crew rescue.
So how do these DSRVs operate?
“Every submarine undergoes periodical sea checks and has a highly specialised crew onboard for its operations. The SOPs are well laid out and followed to the hilt, without any exception. Despite the best of the efforts, rarely accidents occur due to various reasons like material failure or human errors etc. Incidents like Russian Kursk submarine sinking and fire accident onboard INS Sidhuratna had highlighted the need for a submarine rescue vessel. India’s first DSRV was procured from the UK and successfully operationalised by Indian Navy after successfully completing Sea Trials in June 2019,” the C4I expert says.
“According to the specifications of the DSRV, it can recover submarine crew from depths up to 650m. The DSRV is equipped with sonar and an ROV (Remotely Operated Vehicle) to clear the underwater obstructions and for the rescue operations. The DSRV can be transported to the area of operations by air or sea routes.”
How does it work underwater?
“The critical activity in the DSRV operations is the underwater ‘mating’ of the DSRV with the hatch of a submerged submarine and create an air-lock for crew transfer from the submarine to the DSRV for their recovery. As a special arrangement, the hatches of the submarines had required reinforced strengthening so as to be able to handle the load of the DSRV without buckling under the load,” Milind Kulshreshtha adds.
In conclusion he says, “The possession of DSRV vessels makes Indian Navy exclusive in the region, and it is planned to make India as the Centre of Regional Excellence for Submarine Rescue missions. The Hindustan Shipyard Limited (HSL) has launched work on Diving Support Vessels (DSV) project for construction of two 118m 7650 tons DSVs. The vessels shall be based at Vizag and Mumbai. These ships have 12 man saturation diving capability, towed sonars and the DSRV. The DSVs and DSRVs provide the much required submarine rescue capability, unique to the IOR.”
The Indian Navy has confirmed to Financial Express Online that “The Navy’s Deep Submergence Rescue Vessel (DSRV) departed from Visakhapatnam to support Indonesian Navy in Search & Rescue efforts for KRI Nanggala.”