During the Falklands/Malvinas war, a single Argentine Type 209 managed to elude 15 British frigates and destroyers and the antisubmarine aircraft of two carriers. The San Luis maneuvered into torpedo range of the British fleet and launched three torpedoes, although all three shots were unsuccessful. Early in the conflict a British submarine sank the Argentine cruiser General Belgrano with two straight-running torpedoes of a design that dated to World War II.
San Luis reported two attacks on Royal Navy ships during the war. On May 1, 1982 the ships HMS Brilliant and Yarmouth were sent to hunt down the San Luis operating north of Stanley. San Luis reported firing one German-made SST-4 torpedo at the ship which subsequently missed.
San Luis attacked again on the night of May 10. Alacrity had made passage up Falkland Sound, sinking an Argentine merchant navy ship on the way. As Alacrity left the channel before dawn, its sister ship Arrow was waiting to escort her back to the Task Force. San Luis detected the two ships and fired two SST-4 torpedoes upon them. But the first torpedo didn’t leave its tube and the second one was fooled by the Arrow’s torpedo decoy.
San Luis returned to Puerto Belgrano on May 17 in an attempt to fix her weapons system but the war ended before she could sail again.
The U.S. chief of naval operations at the time, Admiral Thomas Hayward, confirmed this assessment twenty years later. As the Falklands campaign reached its climax, “Britain was on the edge. One more loss” of a naval combat or support vessel, “and Thatcher could not have sustained” the war. A hidden factor was the “brand-new” and well-trained Argentine submarine force. If one of its boats had managed to put a torpedo or two into the Queen Elizabeth or another vessel, “that was it.” But combat revealed a fatal flaw in the torpedo control software system, and the submarines never came into play.
Detail
Frigate Captain Azcueta was ordered to make ready his submarine (ARA San Luis) and sail to the Falklands.
The ARA San Luis was a Type 209 submarine, built in 1974 and it’s condition wasn´t the best: refrigeration ducts and main structure covered with incrustations. Due to the need of getting ready quickly , divers started the cleaning operations because Mar del Plata’s base lack of a dry dock.
When the job was finished, the ship was re-supplied and armed with SST-4 and Honeywell Mk37 torpedoes.
By April 11th ARA San Luis was at the sea, travelling to the Falklands. During one of the exercises the fire director computer broke down. Azcueta informed his superiors, but with the lack of any other submarine (ARA Salta was at the dry dock) the mission had to continue.
The first contact with the enemy navy was in May 1st, when the sonnar detected the presence of one target- classified as a destroyer.
At 1015 hours the San Luis launched an SST-4 to the target, but it failed due to the torpedo-cable being cut. Then the sub was then attacked with depth charges, but managed to escape from its pursuers.
The last “offensive” mission took place May 11 at 0140 when San Luis launched a SST-4 torpedo at one target classified as frigate, but again the torpedo cable failed.
Frigate Captain Azcueta broke radio silence and informed Naval Command of his situation. The order was given return to the base and try to repair the fire director.
By June 14th personnel of ARA San Luis were still trying to fix the sub to return to the Falklands.
The problem with SST-4 was in the fire train , that caused the explosion of the war head and the unrolling system of the torpedo cable.