The Republic of Singapore Navy (RSN) has operated diesel-electric submarines for 20 years, starting with the acquisition of four Swedish-built Challenger-class (ex-Sjöormen) submarines from 1995 and the addition of two Swedish-built Archer-class (ex-Västergötland) submarines in 2005. In 2013, the Singapore Ministry of Defence (MINDEF) signed a contract with ThyssenKrupp Marine Systems GmbH to acquire two new Type 218SG submarines customized to the RSN’s operational requirements. Earlier this year, two of the Challenger-class submarines, RSS Challenger and RSS Centurion, were retired from service.

Competent, Confident, and Committed Submariners

Within the RSN, a robust submarine training system has been developed to train competent Submariners to operate these complex machines in a safe manner. Besides training with the Royal Swedish Navy in the early years, RSN Submariners have participated in training with established submarine-operating navies like the United States Navy, Royal Australian Navy, German Navy, Royal Netherlands Navy, and Royal Navy. The RSN has also sent prospective submarine commanders to the gruelling submarine command courses conducted by the German Navy and Royal Netherlands Navy.

Since the return of the first RSN submarine to Singapore in 2000, the RSN has conducted local submarine courses to qualify new Submariners. In 2015, the RSN’s Submarine Training Centre (STC) was established to co-locate all training facilities and simulation systems, as well as drive all training activities.

The Submarine Training Centre was given the name “RSS Challenger – Submarine Training Centre” in honour of the RSN’s first submarine and training platform.


MV Swift Rescue is a Submarine Support and Rescue Vessel (SSRV)
of the Singapore Navy.


Submarine Rescue: What more can we do?
Although submarines are manned by well-trained and competent crews, there are inherent risks operating these highly maneuverable platforms in the undersea environment. A collision with a surface vessel, another submarine, or an underwater obstruction could severely damage the submarine and render it unable to surface. Therefore, a credible submarine rescue capability is necessary to ensure that Submariners can be rescued from a disabled submarine within the shortest time possible as survivability will inevitably decrease with time.

In 2008, the RSN became the first navy in Southeast Asia to operate an indigenous submarine rescue capability with the launch of the submarine support and rescue vessel (SSRV), MV Swift Rescue. With its deep-submergence rescue vessel, Deep Search and Rescue 6 (DSAR6), MV Swift Rescue offers a fully integrated submarine rescue system able to conduct a range of operations, including rescue, medical treatment, and heli-evacuation of casualties.

The RSN’s approach to submarine rescue is premised on being self-sufficient in all envisaged rescue scenarios and partnering with regional navies to augment existing capabilities to strengthen the overall submarine rescue capability of RSN submarines. We also believe in making available the capability for rescuing other distressed submarines in the region. The RSN has signed submarine rescue agreements with navies like the United States Navy, Indonesian Navy, Royal Australian Navy, and Vietnam People’s Navy, and is working toward similar agreements with other regional navies.

Regional cooperation in submarine rescue was enhanced through the conducting and participating in exercises. This includes the multilateral Exercise Pacific Reach, which the RSN hosted in 2000 and 2010. Navies operating submarines in the Asia-Pacific region came together to exchange knowledge about submarine escape and rescue (SMER), building trust in submarine rescue among the participating navies.

Beyond submarine rescue exercises, the RSN has participated in key SMER conferences such as the North Atlantic Treaty Organization (NATO) SMER Working Group meetings and the annual Asia-Pacific Submarine Conference (APSC). Recently, the RSN co-hosted the 15th APSC with the United States Navy in Singapore. The conference saw a record number of 23 participating navies and SMER organizations. Since its inception in 2001, the APSC has been an important platform to foster mutual understanding and cooperation between the participating navies in SMER issues such as the interoperability of rescue assets both internationally and in the Asia-Pacific region.

Although there is clear emphasis placed on SMER in the Asia-Pacific region, submarine rescue remains a reactive measure and not a preventive one. Like-minded navies need to collaborate on operational safety measures to reduce the risk of a submarine accident.


Challenger-class and Archer-class submarines at sea


Submarine Operational Safety: Why is there a need?
In recent years, the number of submarine-operating navies in the Asia-Pacific region has grown and the number of diesel-electric submarines could reach 130 in five years’ time.1 There is high shipping traffic along the sea lines of communication in the Straits of Malacca and Singapore, as well as across the South China Sea, East China Sea and Sea of Japan. The relatively shallow depths in many parts of the South China Sea do not allow two submerged submarines to operate in the same water column safely. Hence, such areas are akin to a two-dimensional water space rather than a three-dimensional one.

There is also a risk of collision between submarines and deep-draught vessels, fishing vessels, military vessels with deployed undersea devices, unmanned underwater vehicles, and sea-based oil rigs. With an increasing number of submarines operating in such a congested and confined water space, it may not be unreasonable to assume that it is an accident waiting to happen.

To avert a potentially catastrophic submarine accident in the Asia-Pacific region, it is vital for submarine-operating navies to embrace a submarine operational safety framework that is practicable and aligned with national interests, given the sensitive nature of submarine operations.

An obvious method of preventing submarine collisions is to de-conflict submarine movements, as well as deploy undersea devices between affected parties in a given area under the responsibility of a designated Submarine Operating Authority (SUBOPAUTH). For example, NATO adopts a multilateral Prevention of Mutual Interference (PMI) arrangement under a common SUBOPAUTH among its submarine-operating members.2 However, the effectiveness of such a system is premised on trust and close collaboration among its members. While bilateral arrangements on PMI may be readily acceptable in the Asia-Pacific region, it may be a bridge too far for a multilateral framework on PMI. However, there is still room for multilateral cooperation on other key aspects of submarine operational safety.

Sharing Non-Sensitive Information to Enhance Safety
Information sharing and exchange amongst navies have greatly enhanced operational responses against common threats such as maritime terrorism and piracy. Similarly, submarine-operating navies can benefit from information sharing on “non-submarine threats” to submarine navigational safety. For example, a Submarine Safety Information Portal (SSIP) that leverages the RSN’s Information Fusion Centre (IFC) capabilities could provide real-time or near-real-time tracking and locating of deep-draught vessels, fishing activities, sea-based oil rigs, and seismic activities so that national SUBOPAUTHS can put in place the necessary preventive measures. The IFC, located at the Changi Command and Control Centre, maintains an extensive global and regional shipping database and serves as an information exchange node to facilitate timely responses to Maritime Security incidents. In addition, the SSIP can also facilitate submarine rescue by maintaining real-time tracking of Vessels of Opportunity (VOOs) and submarine rescue assets.


2014 Asia Pacific Submarine Conference


Sharing Best Practices and Establishing Common Standards
Besides information sharing, submarine-operating navies can also exchange best practices in non-sensitive areas like material safety, training/exercise safety, and risk management. There is also scope for developing safety procedures similar to the International Regulations for Preventing Collisions at Sea (COLREGS) or Code for Unplanned Encounters at Sea (CUES) to address the situation when two submarines have an unplanned encounter at sea. These initiatives can significantly enhance submarine operational safety, but will require mutual trust and cooperation of submarine-operating navies in the region.

In 2014, the Royal Australian Navy organized the inaugural Submarine Operational Safety Conference (SMOSC) to highlight the need for regional collaboration on submarine operational safety matters. In 2016, the RSN co-organized the second SMOSC with the Republic of Korea Navy to take the initial efforts one step further toward the goal of developing an effective submarine operational safety framework for the Asia-Pacific region.

Over the last 20 years, the RSN has gradually built up a capable submarine force to safeguard Singapore’s sovereignty and maritime economic lifelines. In increasingly congested and confined water spaces within the region, the prospect of a submarine accident is plausible. Hence, it is in the mutual interest of Asia-Pacific submarine-operating navies to collaborate on submarine rescue and operational safety matters. As the saying goes, the sooner, the better.

1 Channel NewsAsia. Singapore proposes framework for submarine operations safety, 21 May 2015,

2 North Atlantic Treaty Organization. NATO’s Submarine Forces: a Pivotal Capability, 25 April 2014,’s%20submarine%20forces,%20a%20pivotal%20capability%20-%20an%20interview%20with%20Commander%20Allied%20Submarines.aspx