A multinational armada of aircraft and vessels battled high winds and raging seas Sunday as they intensified their search for a missing Argentinian submarine, after apparent attempted distress calls raised hopes the 44 crew members may still be alive.
There has been no contact with the ARA San Juan, a German-built diesel-electric submarine, since early on Wednesday.
An air and sea search is under way with help from countries including Brazil, Britain, Chile, the US and Uruguay.
Hopes of finding survivors were revived when the navy said on Saturday that its bases had received seven satellite calls attributed to the submersible.
The signals were received at 10.52am and 3.42pm local time, but they did not lock in, thus preventing a full connection.
However, the navy was unable to confirm that those calls originated from the submarine.
“The communications are so short and the signal so low,” Argentinian navy spokesperson Enrique Balbi said, later adding that the military had yet to have contact with, or detect radar from, the sub.
The calls revived hope that the submarine had surfaced, but a powerful storm that has whipped up waves reaching 7m in height, had made geolocation difficult, officials said.
Balbi said weather conditions were not expected to improve before Tuesday.
Despite the bad weather, “10 aircraft, both domestic and foreign, are in a search rotation 24 hours a day, each in a different area”, he said.
There was a feeling of “cautious enthusiasm”, naval expert Fernando Morales told C5N television.
He said the attempt to use a satellite phone indicated that “the submarine had to emerge to a depth that allowed the call”.
The last regular communication with the San Juan was early on Wednesday, when the submarine was 430km off Argentina’s coast in the Gulf of San Jorge.
Rescuers are focusing on an ocean patch about 300km in diameter, radiating from the last point of contact.
US Southern Command has deployed a Navy P-8A Poseidon patrol and reconnaissance plane with a crew of 21, along with a Nasa P-3 research aircraft, and other equipment and personnel.
The US Navy has deployed two unmanned underwater vehicles that use a sonar system to create an image of large sections of the sea floor.
Britain’s Royal Navy said it had sent the HMS Protector, an Antarctic patrol ship. Balbi said it was following the northward course the submarine would have taken toward Mar del Plata.
Relatives of crew members unfurled a flag at the naval base that read: “Be strong Argentina, We trust in God, We wait for you.”
“We will do what is necessary to find the submarine as soon as possible,” Argentinian President Mauricio Macri wrote on Twitter.
All land communications bases along the coast were ordered to scan for any follow-up signals, as family members of the missing waited nervously in the coastal city of Mar del Plata.
Claudio Rodriguez, whose brother Hernan is aboard the submarine, was hopeful, saying the satellite signals suggested the vessel was still afloat and would be found. “They’ve got to be afloat. Thank God,” he said.
Among those on board is Argentina’s first female submarine officer, weapons officer Eliana Krawczyk.
The navy has not ruled out any hypothesis. A spokesperson said the most likely scenario given was that an electrical problem may have unexpectedly cut off the vessel’s communications.
The TR-1700 class submarine had been returning from a routine mission to Ushuaia, near the southernmost tip of South America, to its base at Mar del Plata, about 400km south of Buenos Aires.
It is one of three submarines in the Argentinian fleet.
Sixty-five metres long and 7m wide, it was built by Germany’s Thyssen Nordseewerke and launched in 1983. It underwent a refit between 2007 and 2014 to extend its use by about 30 years.
At the Vatican, Argentina-born Pope Francis said he offered “his fervent prayer” for the safety of the submarine sailors.