The disappearance, search and final confirmed identification of the A.R.A. San Juan - the lost Argentinian submarine - became a significant event due to its duration, extent of the operations involved, and the prompt aid and support provided by the international community.
Built in Germany in 1983, the A.R.A. San Juan was a 'TR 1700' Class diesel-electric submarine designed by former Thyssen Nordseewerke. She had undergone a mid-life overhaul at CINAR (Complejo Industrial Naval Argentino, a shipyard in Buenos Aires), that ended in 2014.
The last message from the A.R.A. San Juan was received at 07:19 am (local time), on November 15, 2017. The sub was on a peacetime patrol near the limit of the Argentinian Exclusive Economic Zone (EEZ), some 240 nautical miles off Comodoro Rivadavia, a city in Patagonia.
The previous night, facing rough seas, the Commanding Officer had reported a water entry (apparently through the snorkel), which had caused a short circuit in the prow batteries compartment. A fire followed, but it was controlled by the crew. He was then ordered to change course and go back directly to the home port (city of Mar del Plata).
As specified by the established protocol, an extensive radio search in all frequencies was performed.
On November 16, at 02:13 pm, a SUBMISS (submarine missing) message transmitted by the Navy’s Submarine Force triggered the SAR (Search and Rescue) operation. That very same day, the A.R.A. La Argentina (a 'MEKO 360' Class frigate) carrying a helicopter onboard, was deployed to the estimated submarine’s position. Later that day (06:40 pm) a Navy’s S-2T Tracker aircraft arrived at the zone, and begun a visual and radar search. The exploration continued through the night with another Navy’s aircraft (a Beechcraft B-200). Subsequently, most of the Argentine Navy fleet was sent to the area.
On November 17, at 10:08 am, the ISMERLO protocol alarm was activated. (ISMERLO stands for International Submarine Escape and Rescue Liaison Office). Then the Submarine Force Commander gave the bad news to the relatives of the 44 crewmembers.
Despite the very bad weather, ships and aircraft of the Argentine Navy, Air Force and Coast Guard were deployed. The Argentine Army helped with specialists that analysed satellite images. By coincidence, a US Navy (USN) P-3 Orion was stationed in Ushuaia (South of Argentina), working for the National Aeronautics and Space Administration (NASA). It was immediately deployed to carry out search flights. The objective was crystal clear: locate the A.R.A. San Juan and her crew alive, as soon as possible.
The US, Russia and the UK, among many other nations, soon offered their help and assistance. In Puerto Belgrano, home of the Argentine Navy main naval base, a special international work team was created. Besides Argentinian military, it comprised experts from the above mentioned countries and officials of the Ministry of Defence. They all worked together evaluating the available information, and planning and coordinating the search effort.
On November 22, the Comprehensive Nuclear Test-Ban Treaty Organization (CTBTO) announced that a week before (November 15), three stations had received an unusual hydro-acoustic signal coming from a location near the missing submarine last-known position. The system detected a short, impulsive, and broadband signal in a low frequency spectrum not audible to humans. All details and data were available to support the ongoing operations.
Following the SAR protocol established by the Submarine Escape and Rescue Working Group (SMERWG), the USN Undersea Rescue Command (URC) sent two offshore supply ships (Skandi Patagonia and Sophie Siem, both of Norwegian flag) with proper equipment for the operation, dispatched to Argentina in C-5 Galaxy and C-17 Globemaster transport aircraft.
On November 30, at 04:20 pm, the rescue part of the SAR mission formally ended, though decision to continuing search operations with all available means was taken. More than 550,000 square nautical miles in the South Atlantic rough waters were investigated but no trace of the submarine was found.
The international assistance continued and more than 100 underwater contacts were explored. The R/V Atlantis (USA), HMS Protector (UK), Cabo de Hornos (Chile) and Almirante Maximiano (Brazil) carried on monitoring the ocean depths.
Early December, the Russian Navy’s Yantar joined the search. The R/V Yantar carried advanced equipment and has the ability to inspect objects in depths up to 6,000 meters. Russia also provided the Argentine Navy with a Panther Plus remotely operated vehicle (ROV), to be installed onboard a surface ship. For the following four months, the R/V Yantar detected and inspected thirty additional contacts.
Once the international support reasonably ended, search continued only with Argentinian surface vessels until September 2018. Then the Argentine Navy contracted a company specialised in seabed exploration, Ocean Infinity. This firm hired the OSS Seabed Constructor, which was equipped with five underwater autonomous vehicles (UAV) and two additional remotely operated devices. More than 8,000 square nautical miles were swept during 62 days, and 24 new contacts were analysed.
At last, on November 17, 2018, just one year and two days after the date the A.R.A. San Juan went missing, the Argentine Navy announced the wreckage had been found at a place close to that of the hydro-acoustic anomaly, at approximately 900 meters of depth. Also, the first images of the sub were shown. The resistant hull was in a single piece, but damaged and crushed due to water pressure. The rest was scattered in a small area of approximately 80 to 100 meters. The identification was made using a Seabed Constructor’s ROV.
The following day, the President of Argentina finally declared a national day of mourning in remembrance of the 44 crewmembers of the A.R.A. San Juan, now in eternal patrol.
As a conclusion, this unprecedented SAR operation, at least in present times, brought together the efforts of 19 countries, more than 4,000 men and women, 28 surface ships and 9 aircraft equipped with state-of-the art technology. It meant a critical situation for the Argentine Navy, as has not been seen since the Malvinas conflict, and far exceeded current contingency plans. It was also the first time that ISMERLO was actually employed in a real case
Our special gratitude to the Nations and Navies involved, for the efforts and support provided during the SAR operations, as well as the countless expressions of solidarity and remembrance of the 44 A.R.A. San Juan’s submariners.