On October 30, Indonesian state-owned shipbuilder PT PAL Indonesia conducted a torpedo firing test of its autonomous submarine prototype, known domestically as KSOT (Kapal Selam Otomatis Tanpa Awak), in Surabaya, East Java. By 2026, 30 KSOT units are targeted to enter service under the Indonesian Navy (TNI AL) Submarine Operations Command.
The test began with a 324 mm lightweight ‘Piranha’ torpedo—reportedly developed by PT PAL—being loaded into the starboard-side launch tube, which was mounted externally on the KSOT. The torpedo was placed using a mobile crane from the Indonesian Navy (TNI AL) 2nd Fleet Command pier. The autonomous submarine then moved further into the sea before launching the torpedo.
Torpedo loading process using a mobile crane. You can see TNI AL’s first PPA frigate, KRI Brawijaya (320), in front of the KSOT. PT PAL picture.
Close-up photo of ‘Piranha’ lightweight torpedo before being loaded into KSOT. TNI AL picture.
A video released by PT PAL shows the KSOT performing a diving demonstration, although for most of the test, including during the torpedo launch, the prototype remained partially submerged.
‘Piranha’ torpedo being launched from KSOT. PT PAL picture.
As Naval News previously reported, the prototype is 15 metres long with a breadth of 2.2 metres and a draught of 1.85 metres. It can reach a maximum speed of 20 knots and can operate at depths of up to 350 metres.
The KSOT full-size model/prototype was publicly unveiled for the first time during the Indonesian National Armed Forces’ 80th anniversary parade on October 5 in Jakarta.
PT PAL stated that the autonomous submarine is fully designed by Indonesian engineers and with a domestic components level of over 50%, a figure the company aims to increase further in future development and production stages through the use of more locally-made components. The prototype also incorporates commercial off-the-shelf parts and systems, and the experience gained from the KSOT program is expected to contribute to the development of other autonomous platforms, such as unmanned surface vessels (USVs), PT PAL added.
30 Units by Next Year
Close-up photo of KSOT during the test. Indonesian MoD picture.
Minister of Defence Sjafrie Sjamsoeddin, accompanied by Navy Chief of Staff Admiral Muhammad Ali and other senior officials, attended the firing test. The minister stated that the KSOT will undergo continuous evaluation and refinement as part of the ongoing development process.
Indonesian MoD picture.
Moreover, PT PAL claimed that it will produce 30 KSOT units by 2026, all of which will be operated by TNI AL Submarine Operations Command (Koopskasel) to monitor and protect Indonesia’s strategic maritime choke points which include the Lombok and Sunda Straits. However, no additional information has been released on whether all 30 units will be the torpedo variants, as the KSOT is also designed in other configurations, including ISR and kamikaze/decoy. Given its size and operational concept, the KSOT could also potentially be deployed from larger vessels, expanding its flexibility and operational reach within TNI AL fleet structure.