SAN DIEGO (NNS) - The Navy's Deep Submergence Unit (DSU), along with members of the Chilean navy's diesel electric submarine CS Thomson (SS 20), successfully completed a Submarine Rescue System (SRS) exercise off the coast of San Diego during the bi-lateral exercise CHILEMAR II Oct. 27-28.

The exercise required CS Thomson to bottom itself on the ocean floor, at a depth of approximately 450 ft., to simulate a submarine casualty while members of the DSU aboard the Military Sealift Command fleet ocean tug USNS Sioux (T-ATF 171) deployed Navy divers to perform a successful open hatch mating.

"The purpose of this exercise is to confirm submarine rescue capability between the U.S. and Chile," said Capt. David Osen, Naval Reserve Submarine Development Squadron 5's Reserve Component Sub Rescue chief staff officer. "Conducting these exercises fosters more than safety and interoperability, and they also promote greater understanding and commitment to stability and peace through enhancing regional cooperation."

The rescue operation involved divers using atmospheric diving suits (ADS) and a pressurized rescue module (PRM).

The PRM is a submarine rescue chamber (SRC) that is lowered using a tethered line from the ship to the submarine and seals over the submarines hatch. The SRC is operated by two DSU crewmembers and allows for an additional six passengers.

While the hatch was open between the SRC and CS Thomson, gifts were exchanged between the two nations, along with an exchange of CS Thomson crewmembers, before returning to the surface.

The ability of both nations to work together on such a technical exercise allowed both to prepare for the unlikely event of an actual submarine emergency.

"It's good for us to show interoperability with the U.S. Navy and participate with both rescue vehicles," said Lt. Patrico Puyol, CS Thomson liaison officer. "That way we can prove to ourselves and the U.S. that we are capable."

Dealing with highly technical and sensitive equipment such as a submarine or an ADS might raise questions about the likelihood of an actual emergency on a submarine.

"Even as submarines around the world become more sophisticated and capable, they remain subject to the implacable force of the sea and other potential hazards such as collisions, flooding, fire, and equipment failure," Osen said. "Submarine safety and the well being of our submariners is a priority with our forces. Much like an ejection seat on an aircraft or lifeboat on a ship, submarine rescue assets provide the final insurance in the unlikely case of an emergency."

Submarine Escape and Rescue involves some difficult evolutions and therefore needs regular practice to maintain proficiency.

"Although submerged operation by manned underwater vehicles by its nature has inherent risks, we minimize the risks through robust design, in-depth training and prudent operation," Osen said. "Crewmembers who work in such hostile environments have to maintain and operate the highest-tech equipment available and often represent the best each country has to offer."

Should a submarine casualty occur, like the one practiced during CHILEMAR II, there is a system in place to aid in the search and rescue process.

Any nation with a downed or missing submarine can put in an alert to the International Submarine Escape and Rescue Liaison Office (ISMERLO) using the website www.ismerlo.org. ISMERLO would then help coordinate a rescue mission using assets from forces and countries around the world.

The goal of exercises like CHILEMAR II is ultimately a humanitarian one; to save lives at sea and support the mandate for international cooperation found within the Navy's maritime strategy that U.S. submarine rescue capability is extended to distressed submarines of any nation.

"International exercises provide the opportunity to work with our submarine rescue partners," Osen said. "No single country can be the answer, everyone needs everyone."

For more news from Commander, Submarine Force, U.S. Pacific Fleet, visit http://www.navy.mil/local/subpac/.