More help is arriving Thursday in the search for a missing Argentine submarine with 44 crew members as concern grows that the vessel's oxygen supply could soon start to run out, reports the AP. Britain's Ministry of Defense sent a special helicopter with emergency life support pods to join the hunt that includes planes and ships from a dozen nations. An Argentina navy spokesman said Wednesday that searchers were returning to a previously scanned part of the ocean after determining that a previously unnoticed "hydro-acoustic anomaly" was detected underwater on Nov. 15, just hours after the final contact with the ARA San Juan and about 30 miles north of the sub's last registered position. He said Argentine navy ships as well as a US P-8 Poseidon aircraft and a Brazilian air force plane would return to the area to check out the sound.
A US Navy rep later said the unusual sound could not be attributed to marine life or naturally occurring noise in the ocean. The San Juan, a German-built diesel-electric sub, went missing as it was sailing from the extreme southern port of Ushuaia to the city of Mar del Plata, about 250 miles southeast of Buenos Aires. Experts worry that oxygen for the crew would last only seven to 10 days if the sub was intact but submerged. Authorities do not know if the sub rose to the surface to replenish its oxygen supply and charge batteries, however. More than a dozen airplanes and ships are participating in the multinational search despite stormy weather that has caused waves of more than 20 feet. Search teams—including two US P-8 Poseidons and US Navy sailors—are combing an area of some 185,000 square miles, roughly the size of Spain. (Read more submarine stories.)