Since the war with UK over the Falklands Islands in 1982, Argentina's potentially capable naval force, the Armada de la Republica Argentina, (ARA) has suffered precipitous decline, as a result of seriously inadequate funding.
Many of its vessels now languish in port for most of the time, with their weapons systems largely inoperative. Missiles are time-expired. Engineering problems are rife. Some unfortunate incidents, including the highly-publicised alongside capsize in 2013 of the mothballed guided missile destroyer Santisima Trinidad, have served to emphasise the service's problems.
Now, the disappearance of one of the ARA's three submarines, has again put the spotlight on the state of the ARA. The 1983-vintage, German-built TR-1700 type diesel-electric attack submarine San Juan has been missing since November 15. The boat was on passage, with a crew of 44 embarked, between the naval bases of Ushuaia and Mar del Plata, and its last reported position was in the San Jorge Gulf, about half way between the two bases, and approximately 250 nautical miles off the coast.
The 2336-tonne, 65-metre submarine, which is equipped with six 553mm torpedo tubes underwent a major upgrade in Argentina between 2008 and 2013, during the course of which the boat was cut in half, and new engines installed.
A major search and rescue operation is underway, in rough seas, and high winds. Participating surface units include the destroyer Sarandi and corvettes Rosales and Drummond of the ARA, and two British vessels, the ice patrol ship Protector, and offshore patrol vessel Clyde.
Aircraft deployed to search include two ARA S-2E Trackers, an Orion research plane, from America's NASA , which is fitted with magnetronic search equipment, and two US Navy P-8A Poseidon long range maritime patrol aircraft.
There has been no confirmation of speculation that a British nuclear powered attack submarine is in the region.
On November 17 the Argentina Defence Ministry announced that investigations had revealed that the lost sub had made, "seven unanswered radio telephone calls", since November 15.
On November 19 the US military's Southern Command confirmed that US Navy submarine rescue assets, including, a submersible rescue chamber, a remotely operated underwater vehicle, and a pressurised rescue module were on the way, by air, to assist. Also headed for the search area is UK's Submarine Parachute Assistance Group, made up of naval medical, engineering and rescue specialists.
There are a number of possible causes for the sudden disappearance of a submarine. These include striking the sea bed, collision with another vessel, structural failure, crew error, and machinery or weapons related on-board explosion, or gas leakage.
A submerged submarine in difficulties might be able to assist searchers by releasing emergency position indicator radio beacons (EPIRBs), possibly attached by line to the sub, and by transmitting on its active sonar.
