Submarine rescue
Submarine rescue is the process of locating a sunk submarine with survivors on board, and bringing the survivors to safety. This may be done by recovering the vessel to the surface first, or by transferring the trapped personnel to a rescue bell or deep-submergence rescue vehicle to bring them to the surface. Submarine rescue may be done at pressures between ambient at depth, and sea level atmospheric pressure, depending on the condition of the distressed vessel and the equipment used for the rescue. Self-rescue of submarine personnel by buoyant free ascent at ambient pressure is considered submarine escape. Survivors may require recompression treatment for decompression illness.
National and international services exist to facilitate the rapid response to submarine emergencies, including the NATO Submarine Rescue System, and within the US navy the Undersea Rescue Command.
History
The original strategy for surviving a submarine accident was to escape. The first escape systems were based on a mining breathing apparatus, which was a primitive form of rebreather using a soda-lime scrubber. The system used in the first escape from a sunk submarine was the German Dräger breathing apparatus, used when the submarine U3 sank in 1911. Similar systems, such as the Royal Navy's Davis Submerged Escape Apparatus, and the United States Navy's Momsen lung, were adopted soon after. In 1946 an investigation by the RN found that there was no difference in survival rate between using an escape apparatus and an unaided ascent, so the free ascent was officially adopted. Free ascent required the submariner to keep an open airway throughout the ascent to avoid lung overpressure injury due to air expansion with decreasing ambient pressure.The USN adopted the Steinke hood in 1962, which is a hood with a transparent viewport attached to a life jacket, which allowed the user to rebreathe air trapped in the hood during the ascent. Free ascent and the Steinke hood were simple, but provided no environmental protection once the submariner surfaced, and many submariners in the HMS Truculent and Komsomolets incidents died at the ocean's surface due to hypothermia, heart failure, or drowning. During the 1990s most of the world’s navies using submarines replaced their escape systems with the British Submarine Escape Immersion Equipment, or a variation. The SEIE is rated for escape from 185m, covers the user completely, and provides thermal protection and integral flotation that can be linked to other units on the surface.
Some rescues involving recovering the whole submarine to the surface were made, but this required ideal conditions, and more often failed. The successful USS Squalus rescue using the McCann Rescue Chamber in 1939 showed that deep rescue is possible, and provided a redirection in survival strategy thinking.
Built-in escape pods have been investigated by the Russian Navy, and were considered by the US Navy before they decided on a system of deep submergence rescue vehicles which entered service during the 1970s. These were small crewed submarines which could be carried by another submarine, and deployed underwater, making them largely unaffected by surface weather conditions. The first models for the USN could carry 24 survivors. and could be airlifted to a port near to the disabled submarine and mounted on a compatible submarine vessel of opportunity.
Other navies followed this example and developed their own portable rescue capabilities. The Royal Navy’s LR5 Submarine Rescue Vehicle uses a surface vessel of opportunity as the base of operations, and operates in conjunction with the Submarine Parachute Assistance Group and the Scorpio ROV. The SPAG team are set up to parachute into the water at the location of the incident along with air-dropped equipment pods containing rigid-hulled inflatable boats, life rafts, food, water and medical supplies to support survivors evacuating the sunken submarine.
The LR5 and DSRV were due to be replaced the end of 2008. The USN developing the Submarine Rescue Diving Recompression System and the LR5 replaced by the similar NATO Submarine Rescue System, a joint project of Britain, France and Norway. These systems are similar in concept to the Royal Australian Navy's Australian Submarine Rescue Vehicle Remora, and carry out rescue operations in three phases: reconnaissance and possibly site preparation or delivery of emergency supplies by ROV, rescue by deep-submergence rescue vehicle, and crew decompression when needed after transfer under pressure to a surface decompression chamber. There is a trend towards larger capacity rescue vehicles, which will reduce the number of locking on operations and recoveries from the water necessary.
After the Kursk submarine disaster of 2000, the International Submarine Escape and Rescue Liaison Office was formed in 2003 to help coordinate international submarine rescue operations.
During the 2023 Titan incident, discussions surrounding the possible salvaging of the submersible were raised by maritime entities; officials forwarded proposals for the transportation of the DSV Limiting Factor towards the last known location before diving down in search and discovery attempts, an approach that would have costed millions. Some however disputed the suggestion, since the time quantity for the Limiting Factor to arrive, transportation logistics of the submersible to the location along with the length to rescue as well as recover Titan led some to doubt its overall feasibility. Others recommended the consideration of the remaining oxygen on board the Titan. Despite the efforts to locate and rescue the Titan, it was later discovered to have imploded, killing all five occupants.
Timeline of successful submarine rescues
- 1917: On 29 January 1917, the submarine HMS K13 sank in the Gareloch in Argyll and Bute, Scotland, during sea trials with 80 people on board. About 10 hours later a vessel deployed divers who were able to communicate with the survivors. Later an airline was attached to the vessel and the ballast tanks were blown. By midday on the 31st the bows were hauled to the surface and supported by a pair of barges while a hole was cut to let the 48 survivors out.
- 1939: On 23 May the Sargo-class submarine USS Squalus sank in during trials at Portsmouth, New Hampshire. The sister ship USS Sculpin, which was also on site, located the disabled submarine and established that there were survivors. The McCann Rescue Chamber was used to successfully rescue thirty-three survivors from Squalus. At the time of the Squalus accident, Lieutenant Commander Momsen was serving as head of the Experimental Diving Unit at the Washington Navy Yard. The submarine rescue ship USS Falcon, commanded by Lieutenant George A. Sharp, was on site within twenty-four hours. It lowered the Rescue Chamber — a revised version of a diving bell invented by Momsen — and in four dives over the next 13 hours recovered all 33 survivors in the first deep submarine rescue ever. McCann was in charge of Chamber operations, with Momsen commanding the divers. The submarine was eventually raised and renamed USS Sailfish.
- 1973: Pisces ''III, a Canadian deep-sea submersible, was trapped on the seabed at nearly in the Irish Sea on 27 August with a crew of two during a dive to lay telecommunications cable after losing buoyancy and sinking. Two similar submersibles and a remotely operated underwater vehicle eventually found the Pisces III and connected two cables which were then used to lift it back to the surface. Both crew survived.
- 2005: On the 7th of August, 2005, the Russian Priz-class AS-28 mini-submarine was rescued from Beryozovaya Bay off the Kamchatka Peninsula after being trapped at a depth of 190 meters for a duration of over 3 days. The sub got stuck on the 4th of August at a depth of 190m, in cables of the Russian coastal monitoring system. The Russian navy first tried to lift the submarine and then drag it to shallower water where it could be reached by divers, but the cables which had fouled the propellers prevented this from working. On the 7th of August the British Scorpio-45 ROV arrived and managed to cut AS-28 loose. All seven people on board AS-28'', survived.
Methods
Emergency position-indicating radiobeacon is a device used by submarines to signal distress and broadcast their location to rescuers. EPIRBs are typically designed to deploy automatically if the submarine reaches a certain depth, helping rescuers locate the vessel quickly, even if it’s submerged.
The US Navy defines their rescue mission sequence to involve identifying a 'Vessel of Opportunity'; being a vessel capable of transporting a rescue system, and transporting the rescue system to the vessel via aircraft before dispatching the vessel to the location of the distressed submarine.
Escape Immersion Equipment
allows individual escape from a distressed submarine. It is a waterproof, insulated suit with a breathing system and buoyancy control to safely bring crew to the surface, protecting against cold and decompression risks.Refloating the vessel
A conceptually obvious way to rescue the submariners is to recover the whole submarine to the surface, at which point the survivors can either leave through a hatch, or a hole can be cut in the hull to allow egress. In practice this is not often feasible, as it depends on availability of suitable equipment, good weather, and moderate depth.Refloating Submarines has been done in salvage operations, and strategic missions such as Project Azorian where a Soviet Submarine was lifted to the surface by the Glomar Explorer.
Typically however, when the goal is to rescue the sailors onboard, salvaging the entire submarine is considered a secondary priority, with quicker and easier methods of rescuing the crew taking precedence.