Submarine Deployed in Search for Flight 370

AT SEA - APRIL 1: In this handout image provided by the U.S. Navy, The Bluefin 21, Artemis autonomous underwater vehicle (AUV) is hoisted back on board the Australian Defence Vessel Ocean Shield after successful buoyancy testing April 1, 2014 in the Indian Ocean. Joint Task Force 658 is currently supporting Operation Southern Indian Ocean, searching for the missing Malaysia Airlines flight MH370. The airliner disappeared on March 8 with 239 passengers and crew on board and is suspected to have crashed into the southern Indian Ocean. (Photo by Mass Communication Specialist 1st Class Peter D. Blair/U.S. Navy via Getty Images)
The Bluefin-21 is hoisted back on board the Ocean Shield. Photo: U.S. Navy/2014 U.S. Navy

The batteries in the black boxes on Flight 370 were expected to die sometime last week, and since no pings have been detected in six days, the Australian official coordinating the search declared on Monday, "it is time to go underwater." Air Chief Marshal Angus Houston said the Bluefin-21, a 16-foot submersible drone, will be deployed from the Australian ship Ocean Shield on Monday night. The vessel will be deployed for 24 hours at a time to map the ocean floor. An oil slick spotted near the search area on Sunday is being analyzed, but the chance of finding clues on the ocean surface has "greatly diminished," Houston said. "I would caution against raising hopes that the deployment of the underwater vehicle will result in detection of underwater wreckage," he added. "It may not. However, this is the best lead we have."