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.

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.
‘rather than a very limited threat to the Falkland Islands.’
I hope that posters on this site remember these words when trying to use the Falklands as a reason to extract more money from the taxpayer that should be spent on the RN.
If the RN continues in its misguided attempt at keeping up with the Jones by trying to ‘punch above its weight’ on a budget, then what happened to this Argentinian submarine may one day be happening to a RN sub, with worse potential consequences as our subs have nuclear reactors/missiles.
Are you being deliberately obtuse or are you like this all the time? Your comments
are rediculous.
Well two of three Astute class, despite ‘perisher’ have collided with either a rock or ship..maybe RN staff are too busy on diversity/inclusionist workships than learning how to staff and navigate their boats/ships…god, the cancer of political correctness is rife now in the police, army, navy…learn to fight, not learn from feminists/the diversity gestapo how to gut your service of fighters.
Do you take lessons in being an uneducated subject matter bell-end or is it just in your DNA?
No need to be offensive as it makes any point you might have worthless and irrelevant. In a democracy everyone has the right to an opinion whether right or wrong! Just stick to the facts to refute opinions that you disagree with and your responses will be better received.
I hope the end was quick for the crew 🙁 better it end in a blink of an eye than long and painful. At least some old wounds may be healed up a little between the UK and Argentina…now that cant be a bad thing 🙂 RIP San Juan crew o7
Really? A possibly badly maintained piece of german possibly ill-maintained manufactured crap kills some men who hate Las Malvinas? Grow up. Save the tears
How sad you are. Loved ones are missing and you just winge on spouting nonsense.
Thank you very much. I’m from Argentina myself and we’re incredibly thankful for all the help your people provided. I hope this only leads to a better relationship between our countries
Argentina has the bravest sailors in the world.
I wouldn’t go to sea in one of their submarines for all the tea in China.
Anyone can lose a submarine and we might never know the true cause of this disaster. As alluded to in the article, the UKs much vaunted rescue capability is largely as the result of sad experience. That said, the Argentinians were operating with a reckless lack of resources, which is the probable cause. At least they have one ancient Tracker MPA aircraft operational, which is more than us. Nine P8s is not enough. How about some force multipliers?You could operate 4 C295 MPAs for the cost of a Posidon and they would have other potential uses as well. The RAF are rumoured to be in line for some C series to cart around princess Beatrice, etc. Maybe these could have a basic MPA fit out as well . I think that the Canadians would be keen to develop it as a way of avoiding Boeing ever again darkening their doorstep.
‘Perisher’ is garbage. Two of three Astute class subs have collided with a ship or rock, HMS Nottingham couldn’t stagger around Australia ( but somehow Capt Cook could) without running aground, HMS Cornwall had a boat crew seized hostage with no response…a cyber/digital age and £1,000,000,000 million RN boats/ships can’t avoid a freighter or rock, or design a workable destroyer engine? Get a grip, you offend the memory of Nelson and Anson. The RN is a disgrace and national humiliation. But woah, there’s suddenly 52,000, 000,000 euros for Brussels. You disgust me.
Captain Cook actually did bump into Australia quite hard!
You seem to have forgotten the clusterf*** of incompetence that lead to HMS Endurance being written off.
The TR1700 as sold to Argentina was one of the most capable SSK available on the market, deep diving and fast with modern systems. In upgraded form they would still be very credible vs other newer designs unfortunately Argentina has not had the budget to properly maintain them. It looks like the San Juan suffered a similar problem as the HMCS Chicoutimi, unfortunately help was not close to hand this time.
We will probably never know the full details but what we do know is:
1) She was refitted without support of the OEM
2) The Argentine navy has struggled to maintain their vessels
3) The Argentine Submarine service has had a woeful amount of dive time
4) Yet the Argentine navy decided to send the Submarine on an Ocean transit at the edge of the continental shelf rather than send her along the coastline and when they hit bad weather they were forced to proceed dived using the snorkel
5) Forcing a crew who has had barely any dive time in a submarine with a questionable refit and poor long term maintenance into the most dangerous situation possible
What would be your best guess? I was thinking that the crew were probably overcome with fumes, there is a vague reference to the wellbeing of the crew in the last message.
Well the last message stated there was an electrical fire due to water ingress from the snorkel and she was running underwater on her aft batteries. The impression I get from that message is they had the fire under control or out but the question is what load was being put on the aft batteries and what was the damage to the forward batteries that had caught fire? Also what damage had been done to the electrical system as a whole? Another issue is when the batteries are charged Hydrogen is produced, if they were running shallow trying to charge their batteries via running the diesel engines with the snorkel but struggling to ventilate the fumes properly due to the rough seas dangerous pockets of hydrogen gas could have built up in one of the battery compartments. If the electrical fire had not been suppressed properly or an oxygen candle had been lit to help clear stale air you might well have had a very good environment for an explosion of the batteries or built up Hydrogen. A number of submarines have been lost in those circumstances.
It is worth reading the HMCS Chicoutimi accident report as it gives a very good break down of how this kind of incident can develop:
http://www.crs-csex.forces.gc.ca/boi-ce/rp/hmcs-ncsm/rp/index-eng.aspx#fog
Very informative and a must read for all journalists who want to comment on this story.
I disagree with point 4 – Submarines run best underwater and direct routing is always preferred.
Please don’t refer or compare this event to Chicoutimi; your comparison indicates that you are not fully informed about her and neither is anyone in possession of the facts about SAN Juan yet.
Comprehensive Canadian government report not good enough for you? You can even read through the redactions and get a pretty good idea of how unpleasant it really was.
I doubt we will ever be in possession of the facts about the San Juanita, so we are going to have to speculate. We know that they had a problem with water ingress and a fire, it’s reasonable to speculate that things cascaded from there.
It was reckless to send an unpracticed crew and a boat that was not fully worked up so far out into the ocean in the middle of a big storm. As soon as something went wrong, they quickly ran low on options.
San Juan, dammed spell checker.
You know what I find funniest about Keyboard warriors correcting other keyboard warriors and declaring that the other is not fully informed is that more often then not they are themselves not fully informed!
Unfortunately Pete you fall into that latter category. You would be right in correcting me about my point 4 if we were talking about Nuclear Submarines but in this case we are talking about a Diesel SSK. For an SSN indeed direct routing underwater is the fastest way to get from Point A to Point B. For Diesel SSK it is different. When transiting the fastest they can run is on the surface albeit their hull form is not optimised for it, the reason being they can run up their diesels at full chat. The second fastest is to be close to the surface and snort using their snorkel. There are several limitations which reduce the speed. They can’t run too fast as it increases their wake signature, can cause damage to the masts and tangentially increases the charging time for the batteries as the Diesels can’t run as fast using the Snorkel. A Diesel SSK will surface transit with a top speed of 14kts (on a good day), a snort speed of 5-12kts depending on range required. On batteries submerged up to 20kts but with very limited range. To transit a long distance on batteries would require the submarine to be down at the 5kt or less range to make headway.
In heavy seas as the San Juan was caught running in the surface would be difficult and snorting dangerous due to the chance of water ingress as did happen according to her radio signals. Her signals also stated she was running on batteries submerged, she certainly wouldn’t have been barrelling along at 20kts. After that all we have is speculation
I will compare to HMCS Chicoutimi thank-you very much as it is a very valid comparison and explanation of how this kind of incident can develop.
BMT have an interesting paper out about SSK transit performance, I suggest have a read before Poo-pooing somebody else:
https://www.bmtdsl.co.uk/media/6097911/BMTDSL-Optimising-SSK-Transit-Performance-Confpaper-Pacific-Jan12.pdf
Save the tears. The patrol was at the Falklands’ border, maybe even within, a service which would happily torpedo a British ship. Insincerity displaces a lot more water in tears than a UK navy ship these days. There’s little more nauseating than crocodile tears. Reflect on your enemies’ deaths, don’t labour overlong and weep over them.
Classy
Even in war death is sad, but at least meaningful. In peace time it isn’t even that. Grow up you child.
Those 44 men were fathers, sons, brothers and husbands. Their surviving families will spend Christmas knowing that their perished loved ones are in a steel grave on the bottom of the sea. Give it a rest.
Troll
The ARA San Juan was nowhere near Falklands waters and was performing a port to port transit. Currently Argentina nor its navy is our enemy due to the fact that we normalised relations with them years ago. We keep a watchful eye on them as they have designs on the Falklands but that doesn’t mean we can’t show concern when they loose a vessel during peacetime operations.
We are reflecting. While I get what you mean about insincerity, please remember that the RN was rescuing French sailors hours after Trafalgar and Quiberon Bay.
IF (and frankly its a big if) they are still enemies, then helping them and showing some sympathy might go a long way to ending hostilities.
You are a real cock aren’t you! Your comments remind me of a simple child with a chip on their shoulder! I presume you have never achieved what you thought you deserve to achieve and now want to wet your pants and gash your teeth about it. Rather sad.
If I had to say what I think about all this mess, I’d give them this post. In a sad time like this is for us, we (at least the ones we use our brain, sadly diminishing these days) are incredibly surprised by all the help provided by, well, a long list of countries, but especially the Royal Navy. Given old and not so old conflicts with the UK, we were surprised to see so many resources poured into finding a submarine that has probably sank due to our own country corruption and corner cutting.
By all means, we thank your Navy and all the forces in the world in the help you’re providing us.
In a humanitarian crisis former enemies are just that. Former.
We wish there could have been good news to come out of the search. Our condolences to the survivors families, and you.
Excellent article. I am argentine, by the way.
Interesting point I never saw mentioned: Why did the San Juan have 44 people on board?
The sources I can find claim a complement of either 29 or 26 and 6 empty bunks.