Europe Editor Dim Jones visits RNAS Yeovilton and the Royal Navy School of Survive, Evade, Resist, Extract and Underwater Escape Training Unit – aka “The Dunker”.

Ditching in a helicopter must be one of life’s more unpleasant experiences; I have not tried it myself, but I am happy to take the word of those who have. Add to that the possibility of the aircraft rolling upside-down after impact, and the whole episode occurring in the dark, with a cold sea, rain, high winds and turbulent sea state, and you have all the ingredients of a nightmare. Nevertheless, rotary-wing operations, and particularly those of maritime air forces, have to take into account these unattractive possibilities, and it is, therefore, essential that those who are regularly exposed to such hazards undertake the most rigorous training in order to maximise their chances of surviving such an event.

Underwater escape training (UET) has taken place at HMS Heron (Royal Naval Air Station Yeovilton) for many years, and generations of helicopter aircrew have come to respect, if not love, the Dunker. In a misspent middle age, I sampled its delights myself, and although – in common with the High-G centrifuge – a re-run is not on my bucket list, I left the Dunker knowing that I had received valuable training which might, if things went badly wrong, save my life.

The first RN UET took place at HMS Vernon, Portsmouth, in the early 60s, and used the old Mining Trials Tank (now part of the Gunwharf Quays shopping centre!), before moving to Yeovilton in 1981, and finally consolidating all UET there in 1985. This 30-year-old Dunker set-up had its limitations, however, and the RN have recently moved into a new state-of-the-art facility at Yeovilton.

The Royal Navy Centre for Maritime SERE (Survive, Evade, Resist, Extract) and Underwater Escape Training (RNCMSUET) was opened on 26 February 2018 by then-Assistant Chief of the Naval Staff (Aviation, Amphibious Capability and Carriers) and Rear Admiral Fleet Air Arm, RAdm Keith Blount.

The building is named after RAdm Godfrey Place VC who, in September 1943, captained the midget submarine X-7 in an attack on the German battleship Tirpitz in Kåfjord, Norway. In 1950, Place took the unusual step for a submariner of transferring to the Fleet Air Arm, training as a pilot and gaining his “wings” in 1952. Later that year he saw action in the Korean War, flying the Sea Fury in 801 Squadron from the deck of the carrier HMS Glory. 

The RNCMSUET is MoD-owned, and is commanded by an RN officer; maintenance of the facility is contracted to Amey and sub-contracted to Boden.

Two main types of training are carried out: underwater escape, for which Babcock International supplies the staff, under a three-year contract, ported over from the old facility; and the survival element of SERE training, which remains the responsibility of the RN.

The facility is centred around three pools: an environmental pool; an underwater escape training pool; and a smaller pool specifically designed for training in the use of Short-Term Air Supply Systems (STASS). Together, they contain 1,125,000 litres of water.

Video feeds from underwater showing trainees and support divers.
Video feeds from underwater showing trainees and support divers.

Brace Yourself

The UK’s Military Aviation Authority (MAA) mandates that all rotary-wing aircrew, and those required to fly as passengers in helicopters over the water at night, should undergo initial and refresher training in underwater escape, and that the training currency period should be two years for aircrew whose roles are primarily maritime, three years for other aircrew, and five years for passengers. The UE course takes half a day, and comprises lectures, equipment fitting, briefings and practical pool drill.

The Babcock UET staff is primarily comprised of safety divers, some of whom are also UE instructors, and safety equipment fitters. They are mainly, although not exclusively, ex-military; one of the reasons that UE training was outsourced is that the RN no longer has a Ship’s Diver branch from which to draw qualified personnel and, indeed, most of the current staff’s previous diving experience was recreational rather than professional. These gentlemen (there are currently no ladies on the staff, although there have been in the past) deliver their message in the unequivocal style to which I became accustomed during my years of service and, in common with their Air Force and Army counterparts, go by sobriquets: during my visit, the STASS briefer was Fez, the pool drill was supervised by Nige, and one of the safety divers was Billy the Fish. They display the typically uncompromising manner of the military instructor, but there is no doubt that their aim is to help their trainees to complete the course successfully.

Participants have to be certified medically fit to undergo training, and one minimum requirement is that they are able to hold their breath for 20 seconds. This breath-hold exercise helps generate an initial confidence boost in trainees, and represents the length of time the module remains submerged, although the average exit time is five to eight seconds, with an arrival on the surface a couple of seconds later.

The briefings start with a refresher on the various types of harness fitted to rotary-wing aircraft – generally four- or five-point full harnesses for flight deck crew, and airline-style lap-straps for cabin occupants – and their release mechanisms. This is followed by instruction in the correct ‘Brace’ and ‘Orientation’ procedures. Each exercise in the pool (and, it is to be hoped that time would allow the same in an airborne ditching situation) will start with the instruction to ‘Brace’, which prepares the occupants for impact with the water, and allows them to adopt a position which will protect the head to the maximum extent possible, commensurate with the requirement to orientate. The first few seconds after impact are extremely disorientating, especially at night or if the aircraft rolls inverted. It is imperative that the occupant knows which is his or her primary exit, and how to get there. To this end, the Brace position is modified to allow instant contact with whatever part of the aircraft’s structure will enable orientation to be maintained and the exit to be located. Pilots will probably have hands on the controls at impact, and this is their start position in the Dunker also. Nevertheless, they will have an orientation reference; mine in the left-hand seat of the Sea King was a strut conveniently located next to my primary escape hatch, and I reminded myself of its position every time I strapped in.

The briefing continues with a reminder of the debilitating effects of ‘cold-water shock’ on water entry, the disorientation caused by lack of visibility which could lead to panic, and the dangers of ‘snagging’ on the aircraft structure on exit. Personal buoyancy aids are never inflated in the cabin, and the escapee is instructed to clear the aircraft as quickly as possible, and at 90o to the fuselage, in order to minimise the risk of snagging on debris such as rotor blades.

The pool exercises to be run are briefed, all of which have to be successfully accomplished to achieve a training ‘pass’. These comprise a daylight entry in which the aircraft will remain upright, followed by one in which it will invert after water entry, a twilight/inverted and a night/inverted. There will then be two further runs for those equipped with STASS, daylight/upright and daylight/inverted. STASS is essentially a personal air bottle designed to give two minutes of breathing time, this time decreasing with increased depth, and is carried by all aircrew in their survival jackets.

Frequent passengers, such as Flag Officer Sea Training (FOST) staff, carry a variant known as P/STASS in a bag by their sides. STASS or P/STASS will allow the user time to locate secondary exits if the primary are unusable, and also to assist others who are not STASS-equipped. Prior to UE training, STASS personnel will use the STASS pool to familiarise or refamiliarize themselves with the correct use of the equipment, and will also practise use of their secondary exits from the aircraft.

 A survivor is winched from a single-seat raft.
A survivor is winched from a single-seat raft.

Water Shock

The UET pool is 12m long by 10m wide and 5m deep. It is kept at a temperature of between 20 and 23oC ; there is an aspiration to reduce the temperature, but this would require increased use of protective clothing. It is worthy of note that even this relatively high temperature can induce an element of cold-water shock on first entry, and that sea temperatures of well below 10oC are common around the shores of UK, let alone at higher latitudes. 10oC was the temperature below which fast-jet aircrew operating in coastal waters had to wear immersion suits, and sea drills were carried out in whatever clothing was appropriate to the sea temperature of the day. I recall vividly that first contact with an 11oC sea clad in a flying suit was an attention-getting experience.

There are a number of modules, representing various aircraft types, which can be suspended from a gantry, raised and lowered into the water by winch, and inverted as required. Instructors are in the module with the trainees, and additional safety divers are in the pool to ensure a safe outcome should anything go awry. Various cameras also allow the supervisor on the control console to see what is going on under water, and he can control the module remotely if required. The detachable cabin windows are fitted before each run, and have to be knocked out by the first user of each exit. During the exercises I observed, all went pretty well, save that, on one run, an occupant of the main cabin elected to exit via the large hole at the back (which does not exist in the real thing) in preference to the small one he should have used. He was counselled, and invited to try again.

Surviving the Sea

The other element of RNCMSUET training is the sea survival element of SERE. This is refresher/currency training only, since all initial training is conducted at the Defence SERE Training Organisation (DSTO) at RAF St Mawgan in Cornwall. Essentially, sea survival starts where underwater escape ends – on successful exit from the aircraft – and the RNCMSUET trains all RN aircrew and also Army Wildcat crews, since they are co-located at Yeovilton.

Sea survival training has historically comprised two elements – pool drills and sea drills, for which the currency periods are six months and two years respectively – but the environmental pool at UETU allows both to be achieved on dry land. The pool is 25m long by 12m wide and 4m deep, and is equipped with:

  • wind generators which can achieve a Force 6 over the water;
  • water injectors to simulate rainfall;
  • a wave-generator which can produce a swell of 1m;
  • water impellers which simulate the effect of being dragged through water by a parachute;
  • a gantry-mounted winch, which can pick up a ‘survivor’ from anywhere in the pool and deposit him or her on a platform representing a helicopter door; and
  • a lighting system which can simulate any light condition from full daylight to pitch black.

The training session started off with a classroom session, delivered by the SERE instructor, PO Claire Garrett, who covered all aspects of the safety and survival equipment carried in helicopters – checks, maintenance, correct use and emergencies. All helicopters capable of carrying passengers carry a multi-seat (MS) life raft. Additionally, aircrew are equipped with single-seat (SS) rafts, carried either in a dinghy pack which doubles as a seat, or in a backpack. If the opportunity arises, the occupants of SS life rafts can transfer to an MS raft, so they need to know their way around both; there are also two types of SS raft.

Unsurprisingly for refresher training, the Q&A session revealed a high level of knowledge among the audience. The environmental pool drill covered all aspects of MS and SS drills, culminating in the winching of ‘survivors’ on to the ‘helicopter’.

As with every new facility or item of equipment, it takes a little time to ‘bed in’, and there will always be some teething problems. In the case of the RNCMSUET, these have been relatively minor. For instance, the changes of pressure in the environmental pool chamber caused by the wind- and wave-generators was not anticipated when the doors were designed, the result being that they tend to swing open and closed. The escape module which was used in the old Dunker (representing a Merlin) has been transferred to the new one, but the remainder of the modules are hired in from a Canadian company, and there is no specific module simulating the Wildcat (which is flown by the RN, the RM and the Army Air Corps). There is an aspiration to manufacture their own equipment in the UK, but this will have to compete for funding with other equally worthy projects. Nevertheless, there is no doubt that the new facility represents a major advance in the UK’s UET and SERE training capability. Very few people, I suspect, can honestly say that they enjoy UE or Sea Survival training; however, even fewer – and none who have actually, as I have, been in a sea survival situation for real – would say that the training is not essential, and that it should not be as realistic as equipment, staff, and the constraints of peacetime operation can make it. 


Read Dim Jones' harrowing personal story in "One Less Landing Than Take-Off," reproduced from the trilogy of Out of the Blue books - the sometimes scary and often funny world of flying in the RAF, as told by some of those who were there.​ All proceeds from Out of the Blue, Out of the Blue Too, and Out of the Blue: The Final Landing (published by Halldale Group) benefit UK military charities. Order from the Royal Air Force Association here.

Originally published in Issue 3, 2019 of MS&T Magazine.