Submarine Escape and Rescue

When submerged, submarines may be subject to enemy action, mechanical failure, collision and other accidents that mean it is immobilised and unable to surface. Escape and Rescue are key capabilities. NATO maintains a 24x7 globally deployable submarine rescue capability, based in Scotland.


The need for an effective submarine escape and rescue capability was significantly reinforced in 1939 when the Royal Navy suffered its greatest peacetime loss of life on a submarine, HMS Thetis.

HMS Thetis (N25) was a T Class submarine built by Cammel Laird on the Mersey. During her initial sea trials, a series of events led to her torpedo tubes being opened to the sea. 4 men escaped but 99 were lost. The video below provides a good overview.

Clearly, submarines operate in a uniquely hostile environment and being able to escape, or be rescued, is essential.

Self Escape

Submarines are equipped with their own escape sets to allow personnel to leave the submarine without external assistance using an escape chamber or compartment.

Specialised suits have been a key component of self escape for many years, having a quick cigarette before exiting might not be standard operating procedure now though!

The image below shows an older Mk9 Escape Suit, a far cry from those in the Pathe video.

Since these were introduced, the state of the art has advanced.

RFD Beaufort Limited in Birkenhead have been supplying submarine escape suits to the naval forces of the world for decades, now part of the Survitec Group, they continue to enhance the ‘state of the art’. Describing these as a suit is underselling them because, with the advent of the Mk10, RFD Beaufort integrated a single person liferaft and extensive hypothermia protection into the design

The Mk10 has now been replaced with the Solandri which is designed to sustain the wearer on the surface for 24 hours and includes water, emergency rations, heat packs and signalling equipment.

All submarines are equipped with escape exits. The Astute class submarines have a two-person escape tower called the Logistic Escape Tower (LET) aft and a Forard Escape Tower (FET), not surprisingly, at the pointed end!.

Every submariner must pass the escape course and before the latest facility was built, this training would happen at the 30m Submarine Escape Training Tank (SETT), Gosport.

This has now been replaced with the recently opened £34m Submarine Escape, Rescue, Abandonment and Survival (SMERAS) facility, named the ‘Thetis’ building, after HMS Thetis.

The state-of-the-art building features a realistic simulator capable of mimicking a variety of weather conditions and sea states. 

Trainers can put students through their paces in the water, giving them the opportunity to practise abandoning a submarine and escaping to life rafts while wind, rain and even thunder and lightning rage around them. Submariners can also practise escape from depth methods in a realistic training environment, simulating the expected conditions on board a submarine in distress.

The move to HMNB Clyde is part of a wider project to centralise all submarine activity at one location.

Submarine Rescue

If personnel cannot self-scape they will need to be rescued and obviously, time is of the essence. The UK and NATO maintain two important capabilities to provide external assistance to a stricken or disabled submarine; submarine rescue.

Submarine Parachute Assistance Group (SPAG)

SPAG is a Royal Navy rapid deployment capability that was formed in 1971 in order to provide a rapid worldwide response to submarines in peril. Held at 6 hours notice to move their primary task is to rapidly deploy and provide expert assistance to the disabled/distressed submarine, or ‘DISSUB’.

The group comprises approximately 30 personnel, all trained for submarine rescue and parachute insertion. Equipment includes inflatable boats, life rafts, specialist communication equipment, rations/water and medical supplies.

Submarine Parachute Assistance Group training off Gibraltar

All of this equipment, even including the inflatable boats, can be parachute dropped. After establishing communications with the stricken submarine the SPAG might establish a life raft group, work with others or coordinate an escape, if rescue by the rescue submersible is not possible, for whatever reason.

Members of the SPAG wear the RN parachute badge but a recent Parliamentary Question and Answer confirmed that members of SPAG, not having completed an arduous training course, cannot wear parachute wings.

The Royal Navy Fleet Diving Unit, Royal Air Force, Royal Marines and Royal Logistic Corps also provide specialist support to SPAG.

NATO Submarine Rescue System (NSRS)

The NATO Submarine Rescue System (NSRS) is a personnel rescue system for submariners in peril, co-owned by the partner nations (France, Norway and the U.K.) and managed by James Fisher Defence (JFD). The concept for a submarine rescue system reportedly came from an ex-Royal Navy submariner named Roger Chapman. Whilst laying telephone cables in a small two-man submersible off the coast of South West Ireland they became stranded and were only rescued after a tense three-day stay on the bottom.

NSRS replaced a UK specific capability that used a Perry Slingsby LR5 submersible with a newly designed SR class submersible and supporting systems. The winning consortium was led by Rolls Royce and included Babcock, Perry Slingsby, Divex, Lloyds, Kongsberg, Interpower and a number of others.

Commenting on the £47 million contract award in 2004, Lord Bach said;

This system will give us and our partners the most effective submarine rescue system available. The system will primarily support the three partner nations but will be on standby to assist any nation anywhere in the world.

In 2013 a contract note was published advertising a possible future in-service support contract for NSRS;

The Authority is considering establishing a Contract for delivery of in service-support of the NATO Submarine Rescue System (NSRS) for a period of five years from July 2015, plus 3 option years. The service and operation required shall be delivered within the existing infrastructure arrangement, currently at the HQ based at HMNB Clyde. The Authority may be willing to consider a move to an alternate location providing value for money, and no loss of system availability can be demonstrated.

The NSRS is a globally deployable submarine rescue system currently operated under a Government Owned Contractor Operated (GOCO) arrangement. NSRS primary objective is to provide a world-wide, continuously available and sustainable capability to rescue personnel in the event of the sinking of a Participant Nation submarine.

The Project is tri-national; United Kingdom, France and Norway form the Partner Nations. A Memorandum of Understanding was signed between the Partner Nations committing to the equitable contribution to the cost of the support and operation of the NSRS until 2032. The Partner Nations (PNs), United Kingdom, France and Norway, have procured the NSRS in order to have the capability to rescue a crew from a Distressed Submarine. In addition, to direct the operational deployment of the NSRS, they have established a joint committee, the International Project Executive Committee (IPEC), to act as a single, unified supervisory body.

NSRS consists of several key components, together they make up the most capable deployable submarine rescue system available.

These key components are:

a) The Submarine Rescue Vehicle (SRV) is capable of lifting up to 12 survivors from a DISSUB at 610m and inclined at an angle of as much as 60 degrees. Powered by innovative Zebra batteries, its maximum speed, endurance and manoeuvrability ensure high confidence in its ability to conduct rescues in all probable situations.

b) Portable Launch and Recovery System (PLARS). The PLARS breaks down for transport (by road and air) and can be reassembled on a suitably prepared ship in a few hours. It is capable of launching and recovering the SRV in up to 5m sea height.

c) The Transfer Under Pressure System (TUP). The TUP accepts survivors from the SRV at an elevated pressure and returns them to surface pressure. It consists of two large recompression chambers and supporting equipment, capable of being broken down for transport (by road and air).

d) The Intervention System (IS). A separate self-contained sub system of the NSRS centred around a capable Remotely Operated Vehicle (ROV). The IS will arrive on scene first and prepare the DISSUB for the rescue and maintain survivable conditions therein.

e) Supporting Equipment. Various containerised equipments support the NSRS and they provide electrical power, spares, workshops, communications, tracking and navigation. All are air transportable and capable of rapid deployment and assembly.

Estimated value of the 5+3 year contract was between £20m and £40m

Early in 2014 QinetiQ conducted fatigue and fracture mechanics assessment of the rescue submersible which included a stress life assessment of the welded joints on the pressure hull. This assessment concluded that the joints would only require visual inspections, rather than pressure testing which would have needed the vehicle to be out of service for a number of months. The findings were accepted by Lloyds Register and the UK MOD Naval Authority.

This support contract was eventually let in 2015, to JFD (formerly James Fisher Defence) for £12.1 million. It was called the NSRS Second In Service Support (2ISS) period, JFD beating competitive bids from Rolls Royce and Phoenix International (who manage the US Navy system)

A contract extension to 2023 issued in 2020.

Commenting on the contract extension, Jeremy Quinn, Defence Minister, said;

The safety of our personnel is of the utmost importance and I am pleased we have extended our submarine rescue capability contract with JFD, which will continue to support jobs in Scotland. This contract extension also represents our dedication to the NATO Submarine Rescue System and underpins our continued commitment to ensuring NATO submarine operations remain as safe as possible

The operating concept is deceptively simple, the intervention Remotely Operated Vehicle (ROV) is flown out and operated from almost any ship to establish initial context and carry out a situation assessment. If rescue is viable, the larger rescue submersible and portable launch and recovery system is then flown out and fitted to a suitable vessel such as an offshore supply or engineering ship. Working in conjunction with the ROV, personnel will be recovered and transferred under pressure on the parent ship to a decompression chamber.

Once onboard, personnel can be medically assessed and treated as required. It is of course, more complex in reality than that.

The video below provides a good overview

JFD and FET have built on this to achieve significant export contracts, India and Australia being two notable examples.

Intervention Class Remotely Operated Vehicle (ROV)

The remotely operated vehicle (ROV) is used to locate the submarine in trouble, clear debris and deliver emergency stores pods. Supplied by Perry Slingsby (now Forum Energy Technologies), the Triton SP ROV is a standard Work Class ROV (IROV) of a type in widespread use in the offshore energy sector.

A new capability for the NSRS SRV and ROV was the ability to carry stores pods that can be directly passed through the submarine escape hatch without diver intervention. These pressurised pods can contain a variety of emergency supplies weighing up to 25kg such as food, water, oxygen candles or CO2 scrubbers.

The baseline response time for the intervention ROV is 56 hours based on a 6-hour notice to move from receipt of the DISSUB notification. Kongsberg designed and delivered the control and communication systems, supplementing the traditional through water communications with a Rolls Royce umbilical fibre optic cable. On the mothership, high-quality video and other telemetry information can be received and used to support the rescue.

The ROV can also be equipped for atmosphere sampling.

Portable Launch and Recovery System (PLARS)

The Portable Launch and Recovery System (PLARS) was designed and built by IHC Engineering in South Shields and is a particularly innovative element of the overall system. Fundamental to all the NSRS components is weight reduction, every component has to be air portable to allow rapid global deployment. With this in mind, the PLARS is a modular system that can be broken down into transportable sections and assembled on the host vessel.

When assembled, it can launch and recover the Submersible Rescue Vehicle in Sea State 6 without requiring any diver support, an important safety advantage. Using a sliding table and modular connectors it provides a pressurised route in the decompression chambers, assembled behind the PLARS.

The 100-tonne PLARS has a working load rating of 30 tonnes and for transport, is packed into seven 40ft ISO containers.

The NSRS control centre maintains a continual track of available and suitable ‘vessels of opportunity’ that can be chartered for use with PLARS.

Submersible Rescue Vehicle (SRV)

Christened ‘Nemo’ by the pilots who operate it, the SRV is 30 a tonne manned submersible vessel from Perry Slingsby that can dive to depths of up to 610 metres and evacuate up to 16 people at a time. 

The SRV can mate with the disabled submarine at angles up to 60 degrees.

Its 17 kW h sodium/nickel chloride Zebra batteries provide power and life support is enough for 12 hours of normal use, 96 hours in emergencies.

A new fibre optic communication system has been developed by JFD and Fathom Systems (now owned by JFD) to improve communications between the submarine rescue vehicle, the dive supervisor and the bridge commander, all from the vessel deck.

Transfer Under Pressure (TUP) System

The TUP (Transfer Under Pressure) system, designed and built by Divex, is a portable decompression and medical support unit that allows rescuees to leave the SRV without decompressing, freeing the SRV to quickly dive again.

It can be used to treat 84 people with a maximum pressure of 6 Pa and best of all, fully containerised.

The complete system is containerised, the container integration completed by G3

A 2 person portable system is also used for helicopter medical evacuation.


In 2005, the intervention ROV was deployed to Kamchatka to help a stricken Russian submersible.

Exercise Golden Arrow was one of many deployment exercises designed to provide assurance that NSRS was globally deployable by air. The complete system left Faslane on 28 articulated trucks and was loaded onto 2 C17’s and 3 Antonov AN-124 in the UK and flown to Norway. From there it was transported to the support vessel and deployed in exercise conditions.

Nato Submarine Rescue C17 Loading

Since these initial deployments and exercises, NSRS has continued with regular exercises, recently including…


The UK has an excellent global reputation for submarine escape and rescue; equipment, training, concepts and execution.

The NSRS was, at the time, unique in not requiring a dedicated vessel to operate from. This modularity and air deployability buy time, and time is something that is never in abundance when a submarine is in distress.

Table of Contents



Read more about HMS Thetis

War Memorials Online

BBC Inside Out

The Vintage News

Blackpool Submariners






Change Status

Change DateChange Record
 01/03/2017Initial issue
06/07/2021Content and design refresh
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