Submarines, whether conventional or nuclear-powered, operate in a very difficult and unforgiving environment beneath the waves, where every 10-metre increase of depth results in a pressure increase of one bar or one kg per centimetre square. This pressure further complicates any attempts at submarine escape or rescue from a sunken or disabled submarine (DISSUB).

Since the time the world’s first operational submarine was commissioned into the US Navy in 1900, there have been over 136 peacetime submarine accidents resulting in loss of life. In addition, hundreds of submarines have been lost in various wars, with the majority having been lost in the two world wars.

In recent years, loss of submarines, with their crew, has resulted in national outrage and sacking of senior naval functionaries, as was witnessed after the loss of the 16,000-tonne 144-metre-long Russian nuclear submarine (SSGN), Kursk, with its entire 118-man crew on August 12, 2000, at comparatively shallow depths of 108 metres. The Kursk sank due to explosion of “three to four” of its combat torpedoes with about three tonnes of high explosives, in the foremost (No. 1) compartment (this explosion destroyed the forward half of the submarine, killing most of the crew, and destroying the “integral rescue sphere” meant to enable entire crew escape). It is believed that 23 crew members survived for a few days (in the last or No. 9 compartment), awaiting rescue, which never came, and finally when rescuers entered the submarine on August 20, 2000, they found no survivors.
In 2003, the Chinese Navy made a rare admission, that on April 16, 2003 its conventional Ming-class submarine Great Wall (pennant number 361), was found at sea, with its entire 70-man crew dead, possibly due to oxygen starvation, or carbon monoxide or chlorine gas poisoning. Four senior Chinese Navy admirals were demoted and sacked after this incident.
Today, over 35 nations operate submarines of various types. Very strict standard operating procedures, which vary from nation to nation, are followed for operating submarines and for carrying out search and rescue in case of a DISSUB incident.
When a submarine sinks due to an accident, its crew has the following options available: Depending on the DISSUB depth on the ocean floor and the conditions inside (presence of poisonous gases, heavy flooding, temperatures, injuries, compartment pressure etc), the survivors can carry out the difficult “individual escape” option by donning an escape suit. Some navies that operate Western-origin submarines prefer the Submarine Escape Immersion Equipment (SEIE) Mk 10 for escape from depths up to 183 metres. Other navies that operate Russian-origin submarines (such as Russia, China, India and Iran) use a Russian-origin escape suit which permits escape from 120 metres (though newer versions permit escape from 140 to 180 metres). The survivors, on reaching the surface, require a ship to not only transport them back to harbour but also to provide first aid for any injuries and also high pressure air Recompression Chambers (RCCs) to counter potentially fatal “decompression sickness” which results in nitrogen bubbles forming in the blood when human beings escape from great depths under high pressures. Another potentially fatal injury can be lung damage due to expanding air in the lungs during escape. Individual submarine escape is difficult and requires not only good initial training ashore in 30-metre-high, water-filled “escape towers” but a refresher course every three to five years. The Indian Navy has such an escape tower facility at Visakhapatnam.
A few submarines (for example, the four Indian SSK German-origin submarines), have an integral rescue sphere, in which the entire crew of the DISSUB can escape to the surface, where they embark a rescue ship. However, in case of an explosion (as happened to Kursk) or collision, this rescue sphere may not be available due to damage or inability to “disengage” from the DISSUB, due to hull distortions.
A more viable rescue system is to have a submarine rescue ship (SRS), which ideally needs to arrive the earliest at the accident site to carry out “dry rescue” of the submariners. This SRS, has RCCs, a mini-hospital, a set of trained deep-sea divers, an unmanned remotely operated vehicle (ROV), which can be used to relay video images of the DISSUB, and an underwater telephone for communications with the DISSUB. For the actual rescue, the SRS has one of the two systems available.
The first option is the “Rescue Bell”, which can rescue about 10 men at a time and is lowered from the SRS by wires to the DISSUB. This system is generally limited to 200-metre depth and is also known as the McCann bell. It was first used in 1939 to rescue 33 survivors of the sunken US submarine USS Squalus, from 80 metres depth. Incidentally, the Indian Navy uses a Russian version of this McCann bell on its solitary SRS, INS Neerakshak.
A Deep Submergence Rescue Vessel (DSRV), which can rescue 10 to 20 men at a time, is the present-day choice of most navies. That is because this DSRV, after being lowered into the water from the SRS, can dive independently of the SRS mother ship, to great depths, which depending on the type selected can vary from 300 metres to over 600 metres. Unfortunately, the Indian Navy, which operates 14 conventional submarines and is in the process of inducting nuclear submarines, has no such DSRV-type capability.
The other option available is air transportable DSRVs flown in from a base to the port nearest to the submarine accident site, and then load this DSRV along with RCCs and ROVs on any suitable civilian ship that has been previously checked out and earmarked. The US Navy also has the capability of airlifting a DSRV to any global airport, and diverting one of its four dozen nuclear SSNs to a suitable port, where it can carry the DSRV “piggy back” and then proceed to the DISSUB site. Media reports say that an Indo-US agreement provides this option to India in the event of a DISSUB incident, albeit with a time penalty, which may become unacceptable in some cases.
The Indian Navy, with a solitary vintage submarine rescue system, urgently needs at least two SRSs with two DSRVs (one for each coast, to avoid a cross-coast transit time of four days). Indeed, to cater for maintenance, three such systems would be ideal. The SRS’ should be built in India while the DSRVs, RCCs and ROVs could be “built in India” or imported.
In the complex world of submarine escape and rescue, fortune favours not only the brave but also those who are trained, ready and properly equipped. Our submarine crews patrolling the ocean depths deserve a viable rescue capability.

The writer is a Vice-Admiral who retired as Flag Officer Commanding-in-Chief of the Eastern Naval Command, Visakhapatnam