Bluefin-21 Sub Launches Deep Dive in Flight 370 Search

April 14, 2014— -- Search crews have stopped seeking “pinger” signals in the search for missing Malaysia Airlines Flight 370, instead deploying an underwater vessel to the southern Indian Ocean in a process officials describe as painstakingly slow.

Angus Houston, retired Australian air chief marshal, who is head of the joint agency coordinating the search for the missing jetliner, discussed the updates at a news conference today. Houston said the Bluefin-21 will be deployed, creating a sonar map of the area to chart any debris on the sea floor.

READ MORE: Malaysia Airlines Flight 370 -- What Happens Now?

Crews had picked up a series of underwater sounds in the past two weeks that were consistent with an aircraft’s black boxes. But the black box pingers only have battery life for about a month, and given the plane’s March 8 disappearance, officials believe too much time has passed for any new signals.

"We haven't had a single detection in six days, and I guess it's time to go under water," Houston said.

Officials are hoping to find the black boxes in order to understand what happened to the jetliner, which disappeared with 239 people on board.

Houston warned that the switch to the submarine remains a slow process. The Bluefin-21 will take 24 hours to do each mission, including two hours to dive, 16 hours to search the bottom, then two more hours back up and four hours to download data.

Additionally, the sub will need up to two months to canvass the latest underwater zone. The deepest the sub can dive is 15,000 feet , the depth from which the signals were coming.

Search crews will continue scouring the area for visual debris, with 12 planes and 15 ships involved in today’s efforts.

The Associated Press contributed to this report.