BUENOS AIRES: A multinational armada of aircraft and vessels battled high winds and big seas on Sunday (Nov 19) as they intensified their search for a missing Argentine 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 sub, since early Wednesday.
An air and sea search is underway with help from countries including Brazil, Britain, Chile, Uruguay and the United States.
Hopes of finding survivors were revived when the navy said on Saturday that naval bases had received seven satellite calls attributed to the submersible.
The signals were received at 10.52am (1352 GMT) and 3.42pm (1842 GMT), 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," Argentine navy spokesman Enrique Balbi said.
If the signals are found to have indeed originated from the search area, "we could confirm that it is the submarine," Balbi added.
The calls revived hopes that the submarine has surfaced, but a powerful storm that has whipped up waves reaching seven-metres high has 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 is a feeling of "cautious enthusiasm," naval expert Fernando Morales told C5N television on Sunday.
He said the attempt to use a satellite phone indicates that "the submarine had to emerge to a depth that allowed the call."
The last regular communication with the San Juan was at 1030 GMT on Wednesday, when the submarine was 430 kilometres off the coast in the Gulf of San Jorge.
Rescuers are focusing on an ocean patch about 300 kilometres in diameter, radiating from the last point of contact.
The US Southern Command said on Sunday that it was sending a second Navy P-8A Poseidon aircraft to join the search. The Florida-based plane and a crew of 21 are to reach Argentina later in the day.
A NASA P-3 research aircraft is already participating in the search, the Southern Command said.
The California-based Undersea Rescue Command also said it was deploying two underwater crafts designed to rescue trapped submarine sailors at different depths, as well as a remotely operated underwater robot known as an ROV.
Britain's Royal Navy said it had sent an Antarctic patrol ship "HMS Protector" to join the search.
Balbi said it was following the northwards course the submarine would have taken towards 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."
'GOT TO BE AFLOAT'
"We will do what is necessary to find the submarine as soon as possible," Argentine President Mauricio Macri wrote on Twitter.
All land communications bases along the coast were ordered to scan for any followup 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, 35-year-old weapons officer Eliana Krawczyk.
The navy has not ruled out any hypothesis, a spokesman said. The most likely scenario given is that an electrical problem may have unexpectedly cut off the vessel's communications.
PRAYERS FROM THE POPE
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 400 kilometres south of Buenos Aires.
It is one of three submarines in the Argentine fleet.
Sixty-five metres long and seven metres 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, Argentine-born Pope Francis said he offered "his fervent prayer" for the safety of the submarine sailors.