US Sensors May Have Detected San Juan's Fate

The US Stars and Stripes publication, which informs the US military, has provided the most definitive statements yet on the approximate location and likely fate of ARA San Juan. On Thursday 23 November 2017 Stars and Stripes, reported:

“Ships and planes hunting for a missing Argentine submarine with 44 crew members will return to a previously search area after officials said Wednesday [22 November 2017] that a noise made a week ago in the South Atlantic could provide a clue to the vessel's location."

The Argentina navy spokesman, Capt. Enrique Balbi, said the "hydro-acoustic anomaly" was determined by the United States and specialist agencies to have been produced [on 15 November] just hours after the final contact with the ARA San Juan and could have come from the sub.

The sound originated about 30 miles north of the submarine's last registered position, he said.

"It's a noise. We don't want to speculate" about what caused it, Balbi said.

He said Argentine navy ships as well as a U.S. P-8 Poseidon aircraft and a Brazilian air force plane would return to the area to check out the clue, even though the area already was searched.

In San Diego, U.S. Navy Lt. Lily Hinz later said the unusual sound detected underwater could not be attributed to marine life or naturally occurring noise in the ocean. She declined to speculate whether it might have been an explosion, saying experts did not know what it was.

"It was not a whale, and it is not a regularly occurring sound," Hinz said.

COMMENT

The sensors that picked up a man-made/equipment sound on Wednesday 15 November 2017 (the day San Juan disappeared) may have been hundreds of kilometres away from San Juan. The US would likely be reluctant to specify further about its sensors. Use of sensors often involves a process of retrospectively playing back old recorded sounds/signals or "triangulating" or "cleaning up"  signals picked up by several separate sensors.

Possibly what happened is:

-  after San Juan reported its “electrical/battery malfunction” to base San Juan took the standard
   action of reaching snorkeling depth or fully surfacing due high storm waves interrupting snorkeling
   functions

-  once San Juan surfaced, its crew performed the usual practice of opening the hatches to open air, 

   so as to stand on the "conning tower"/fin/”sail” for lookout/navigation purposes and perhaps to help
   expel battery gas.

-  if there was already stormy conditions, operating on the surface can be dangerous

-  waves can crash over the fin/sail and water can pour through open hatches

-  Seawater can unbalance a submarine. If water gets into contact with a submarine's mass of
   electrical equipment/batteries this can cause short circuits.

-  A chain of many hazards can then result, including catastrophic fire, explosions, and release of
   poisonous chlorine, carbon monoxide and poisonous/explosive hydrogen gases.

-  Secondary explosions can be caused by oxygen cylinders/generators, burning batteries, torpedo fuel

   and warheads “cooking off”

Explosions can sometimes be heard by sensors hundreds of kilometres away.

BACKGROUND/COMMENT PRECEDENT

In 2004 the Canadian Victoria class diesel-electric submarine Chicoutimi experienced a sequence of events that may have occurred in ARA San Juan.

On 4 October 2004 Chicoutimi was travelling from UK to Canada. Chicoutimi was forced to travel on the surface for the first stage of the passage. On 5 October Chicoutimi was passing through a storm with 6 metre seas. Water entered the conning tower/fin/sail. 

Mistakes in opening all the "conning tower" hatches allowed about 2,000 litres of sea water into Chicoutimi. Water contacting electrical equipment led to electrical explosions and fire erupting.  In order to fight the fire, all systems aboard Chicoutimi were shut down, leaving Chicoutimi dead in the water. If the fire had burnt batteries, oxygen cylinders, torpedo fuel or warheads Chicoutimi would have been destroyed. But Chicoutimi was lucky.

As Submarine Matters indicated on November 18, 2017 San Juan was likely unlucky.

The lower red dot in the shaded "Search Area" marks where “Ships and planes hunting for a missing Argentine submarine with 44 crew members will return" based on US information (Map courtesy UK Sun newspaper).

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Pete