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Around The Fleet

Escape From Below:

Pressurized Submarine Escape Trainer

This is a place where no light enters and only the creatures of the deep thrive, it is the deep, dark, cold, crushing depths of the world's oceans, this is the home of the Navy's "silent service."


But what happens when a submarine isn't able to surface? How do the Sailors make it back to the surface?

At the Navy Submarine School at Naval Submarine Base New London in Groton, Connecticut submariner students are taught just how to survive that worst-case scenario.

A two-day class in the state-of-the-art facility at Momsen Hall is real-life training from the Sailors that know working at depth first hand: Navy divers.

Upon entering Momsen Hall, the smell of chlorine and humidity grows heavy in the air as you walk down the passage way - its walls decorated in history and pride of the Navy diver.

"What we do here is we teach real-time submarine escape," said Petty Officer 3rd Class Anthony Clark, a Navy diver and instructor at the escape trainer. "Knowing how subs operate it's never in a good place, it's never in the Caribbean, and it's always some place you don't want to be."

On the first day students go through medical screening and are tested on their ability to perform the Valsalva maneuver, the attempted forceful exhalation against a closed airway - the same way you may try to clear your ears when flying.

"We want to make sure their body can undertake pressure before we even get to the pressure testing," said Clark.

Some people's anatomies just can't do it. The students are taught basic diving physiology and the types of things that can go wrong before we can do the pressure test." - PO3 Anthony Clark

Three photo collage of Sailors standing by a pool, a Sailor underwater training, and back of an sub-escape instructor.


The second phase of the pressure testing, candidates who have successfully performed the Valsalva maneuver will be subjected to increased pressure.

"We put them in a [dive] recompression chamber with a Dive Medical Technician (DMT) and we press them down to 60 feet," said Clark.

Though the dive chamber is at sea level, inside the students feel like are 60 feet below the surface. As the students are pressed down to that 60 feet, if they are unable to perform the Valsalva maneuver, the test stops, and pressure is slowly released so the student can exit. Pressure builds within the chamber until the chamber is equal to water pressure at "escape depth."

Students head back to the classroom for more instruction on the physiological challenges of making a pressurized escape. This instruction shows that no one is immune from the hazards of the deep and that this is more than just a class on Navy Knowledge Online. After this last part of classroom work the students move to the more rigorous and fun part of training, it's time to get wet!

Throughout all of the training, one phrase is constantly repeated: "Never ever hold your breath!"

Our job here is to ensure the students safety." - PO2 Frank Phelan


"Our biggest concern here is POIS, or Pulmonary Over-Inflation Syndrome, that involves having gas-filled spaces in your body expanding to the point where they rupture and we don't want that happening so we teach the students to never ever hold their breath," said Phelan, a Navy Diver and high risk training instructor at the sub escape trainer.
Photo collage of Sailors donning floating devices, a Sailor in a sub-escape suit, and an instructor teaching Sailors.


Follow that chlorine you smelled when you were first came in. At the end of the hallway is a circular tank 37 feet deep.

The tank is heated to 90 degrees and in the enclosed space sweat runs down the student's faces.

One by one the students enter the tank with the instructors. Holding onto the ladder, the students take a deep breath and submerge and start to blow bubbles. This is to make sure the rate of their breath exhaling is correct and that they get used to never holding their breath.

After they pass this section, the students gather around the tank and put on bright yellow Training Life Jackets (TLJ).

They walk down a couple decks below and enter a room. A large panel displays gauges and valves. The students line up and four at a time enter a small chamber with an instructor. The hatch closes and water begins to fill the chamber. The water is at neck level and the students wait for another hatch to open. It opens 15 feet below the surface of the main tank. Waiting outside in that big tank are two instructors. Opening the hatch, a student takes a deep breath from the chamber and ducks through the hatch, he is held for a moment so the instructors can watch his breath rate to ensure he is exhaling all the way to the surface.

After passing this portion, the students head back up to the top of the tank to complete their final test. Escaping from the bottom of the tank.

The students watch in awe as their instructors provide multiple demonstrations of what they'll soon be doing themselves. One diver is in the middle of the tank occasionally looking down into the water. The only ripples are from his hands and feet to keep him steady. Suddenly a rush of bubbles breaks the surface, he looks down as an orange clad Sailor shoots to the surface.

We teach them to exhale or shout 'hooyah!' all their way up to the surface to ensure they're not holding their breath." - PO3 Anthony Clark.


"If they were to hold their breath that could lead to an array of problems - the worst case scenario being death," said Phelan. "That's what makes this some of the most dangerous training in the Navy."
Photo collage of a Sailor inside a pool, and photo of student smiling at an instructor.


If at any point a student cannot complete a stage due to sickness, light limited duty or if they hold their breath during the 15-foot escape during this high-risk training he or she will not be rejected as unfit for submarine service, but they won't be allowed to proceed further with pressurized training.

Making it to the surface is just half the battle, now what do you do? With one-on-one instruction students also learn surface survival. The students don bright orange suits and enter the tank with an instructor and a small one man raft. The student must show the instructor he or she can successfully get in the raft unassisted, zip it closed and drain out any water that may have gotten in it. Once they have completed this, the instructor flips the raft upside down, as a wave might do in real-life, and the student must safely exit the raft while upside down.

Throughout the two-day course students came face-to-face with a hazard that they know will be more dangerous in real life as it won't be in a 37-foot, calm, 90 degree training tank.

The Navy's silent service: operating beneath the waves for over 100 years. From the Alligator and H.L. Hunley of the Civil War to the attack and ballistic missile submarine force of today, they are the original stealth weapon and the Sailors at Momsen Hall ensure the next generation of submariners have the skills they need if the worst case scenario strikes.
Infographic on the Submarine Escape Trainer. Facts will be provided at the end of story.


Momsen Hall Submarine Escape Trainer:
The tank is 20 feet wide and 37 feet deep. Contains 84,000 gallons of water.
Communication station is 15 feet below floor level and can hold up to four people.
SEIE Suit (Submarine Escape and Immersion Equipment Suit)
Escape and survival suit approved for escapes from 600 feet, provides thermal protection and comes with as single seat life raft.