Reflecting on the sad loss of Argentine submarine ARA San Juan

Argentine submarine ARA San Juan has disappeared while on routine patrol and was last heard from on 15th November. After reporting technical problems, she failed to make contact again and by the 17th, the Argentine Navy announced she was missing and had begun a search operation.

The San Juan is one of three conventional Argentine submarines, she was built in Germany in 1985. Her TR-1700 class sister vessel is the ARA Santa Cruz, while the older ARA Salta is a Type 209 (sister of the retired San Luis, a veteran of the Falklands war, which made plausible claims to have launched failed torpedo attacks on HMS Alacrity and HMS Invincible). Although very old by western standards, the San Juan completed a major refit and modernisation 2008-13.

An international rescue effort

When she sailed from Ushuaia, San Juan was carrying 44 people, 37 crew and 7 special forces personnel, including the first woman to serve on an Argentine submarine. More than 4,000 personnel from a dozen countries joined the search and rescue effort. Ships and aircraft have been scouring 190,000 sq miles of stormy ocean, an area about the size of Spain. The United States sent two P-8A Maritime patrol aircraft and a NASA P-3 Orion. They also delivered by Air to Argentina their Submarine Rescue Chamber (SRC) and the Pressurized Rescue Module (PRM) a tethered, remotely operated submarine rescue vehicle.

HMS Protector joined the search on 19th November and is still searching the seabed using her multi-beam echo sounders. HMS Clyde was recalled from South Georgia and made the long journey north to join the search. The Royal Navy’s specialist 10-man Submarine Parachute Assistance Group (SPAG) were deployed from the UK to the Falklands. Their role is to act as first responders when a submarine in distress is located and parachute into the sea with inflatable boats and medical equipment to assist personnel who may have escaped the submarine.

An RAF Voyager aircraft made the longest ever non-stop UK military flight to deliver 3 tonnes of specialist rescue equipment, including 12 deep emergency life support pods. This was the first time a British military aircraft has landed in Argentina since the Falklands war. An RAF C-130 Hercules based in the Falklands also participated in the search. While the search continued for several days in very poor weather, various reports of possible satellite phone calls, noise detection and a ‘heat patch’ all raised false hopes.

The view from HMS Protector’s bridge as she encounters 10-metre waves on 20th November, while searching the South Atlantic for the missing submarine. (Image: @Protector_HMS via Twitter)

A needle in a haystack

Hydroacoustic data recorded by the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) has found that a short explosion occurred on 15 Nov 13:51 GMT (Lat -46.12 deg; Long: -59.69) in the vicinity of the San Juan’s last reported position. It took over a week for this discovery as the vast amounts of data had to be analysed. The global network of hydrophones owned by the CTBTO are designed to record any disturbance caused by underground nuclear testing but are not optimised for tracking submarines. The explosion must have been of reasonable magnitude as the CTBTO hydrophones that detected the sound are thousands of miles away at Ascension Island (Mid Atlantic) and Crozet Island (Southern Indian Ocean). With the report of an explosion and 8 days having passed, by 23rd November it was clear the crew could not have survived and the rescue effort had become a recovery operation.

Several ships equipped with hydrographic sonar are now scanning the seabed for wreckage within a radius of few miles of the explosion point identified by the CTBTO. Ships involved in the search the US Research Vessel Atlantis, Argentinian vessels; Research ship Austral, Survey ship Puerto Deseado, Fishery protection ship Victor Angelescu, Chilean research ship Cabo de Hornos and Antarctic patrol ship HMS Protector. If the wreck is located and the weather is favourable, there are several ROVs that could be deployed.

The loss of the San Juan bears some resemblance to the loss of the USS Scorpion in June 1968. The Scorpion sunk off the Canary Islands whilst submerged. The cause of her loss has never been clearly established but her wreck was found in October 1968 using hydroacoustic data from the SOSUS hydrophone network used to track Soviet submarines combined with Bayesian search theory (a mathematical probability model). The Soviet submarine K-129 was also lost to an explosion of some kind in March 1968, somewhere in the Pacific. Despite an extensive search, the Soviet Navy was unable to find her. Using SOSUS data, the US Navy was able to narrow down the search area and located her in October 1968.

Many people do not fully appreciate the vast size of the oceans, even in a modern world of GPS and easy global communication, finding craft sunk at sea can take a great deal of time or even prove impossible. To date, the main wreckage of airliner MH370 lost somewhere in the Indian Ocean in 2014 has yet to be found, despite the most expensive search in aviation history.

What could have happened?

(This is informed speculation only, based on the limited available facts) The evidence of a short explosion record by the CTBTO points to one of two causes. Either San Juan suffered some kind of flooding incident and went into an uncontrolled dive, passing through crush depth and the hull imploded due to water pressure. Alternatively an internal explosion, either a torpedo malfunction or batteries, which could have quickly disabled and sunk her. During her last communication which has now been made public, San Juan reported water had entered the vessel through its snorkel, causing “the beginning of a fire” and short circuit in the forward battery which had been dealt with. The submarine was encountering big seas at the time, making it difficult to snorkel or proceed on the surface and she was ordered to make for Mar del Plata submerged, transiting slowly drawing power from the aft battery. This would tend to suggest a sea-water induced battery explosion as a likely cause.

It is possible the wreckage will eventually be located and some evidence gathered as to the cause of her loss. The search area straddles the edge of the continental shelf where the sea floor drops away down to 1,000 – 5,000m deep in places. If she went down in this very deep water it might be possible for an ROV to visually survey the site but recovering wreckage for any kind of meaningful analysis could be extremely difficult.

Recrimination and disinformation

As part of a Kremlin-inspired disinformation campaign, a Russian ‘expert’ Captain Vasili Dandikin has theorised that “a British mine planted during the Falklands war was responsible for the sinking of the San Juan”. Mines are essentially a defensive weapon and the RN did not deploy a mine-laying capability during the Falklands war. The Argentines did lay some sea mines around the islands, (observed by submarine HMS Spartan) but they were swept by RN teams after the war. Even more pernicious are bizarre claims by Argentine extremists that “a Royal Navy submarine sank the San Juan”  The RN is now down to just 6 attack submarines as can deploy a maximum of 2 or 3 boats simultaneously. RN priorities now centre around monitoring Russian submarine activity, rather than a very limited threat to the Falkland Islands. It is extremely unlikely there is a British submarine in the South Atlantic. Even if there was, there would be no possible reason to make such an unprovoked attack, which would benefit no one.

In Argentina there is anger and the hunt is on for scapegoats. Many are accusing the government of “killing those sailors”. Without the full facts, it is impossible to know if this was just an accident caused by severe weather, bad luck or a chain of events aggravated by the poor material state of the vessel. Everyone should remember that all submarine operations carry an inherent risk and things can go wrong quickly.

A navy with an unhappy recent history

The Argentine navy, plagued by underfunding has suffered a series of mishaps in recent years, although until the San Juan, none had caused loss life. In April 2007 the icebreaker ARA Almirante Irízar suffered a major fire at sea which required the entire crew to be evacuated. The vessel was eventually towed home but funding issues delayed her rebuild and she only put to sea again in 2017. In 2012 sail training ship ARA Libertad was impounded for 10 weeks in Ghana due to unpaid Argentine government debts. Inactive since 2004 the Argentine-built Type 42 destroyer Santísima Trinidad capsized at her moorings in 2013 after an internal valve failed. She has now been re-floated and will be converted to “a museum dedicated to the 1982 war”. In June 2014, sister of the San Juan, Santa Cruz ran aground near Buenos Aires while on her way to be refitted. During June 2016 ARA Esporta dragged her anchor and collided with a merchant ship in Puerto Belgrano. In June 2017 the destroyer La Argentina rammed a pier at Punta Alta Naval Base, badly damaging her bow and then suffered a fire during welding work to repair the ship.

Every navy has discovered, maintaining a credible and safe fleet requires a complex logistics tail and training organisation to keep equipment at people at peak efficiency. Submarine construction, maintenance and training are especially demanding and there are few corners that can be cut without boats becoming a liability.

Accidents are by no means unique to the Argentine navy, the mighty US Pacific fleet has suffered a series of recent fatal catastrophes, primarily due to operational demands being prioritised above training. The RN has also had incidents of its own, although mercifully has not lost a submarine at sea since HMS Affray sank in April 1951 with the loss of 57 lives, probably due to a snorkel problem.

As the international response has demonstrated, despite being adversaries at times, submariners of all nations have common cause with others in peril under the sea. Let us also hope the considerable British contribution to the rescue effort can be a stepping stone towards improving relations with Argentina. May the 44 on eternal patrol rest in peace and the bereaved families someday find closure.