PERTH, April 22 ― The Bluefin-21, an autonomous submarine sent by the United States to assist in the search for missing Malaysia Airlines flight MH370, has now completed seven missions and scanned more than half of the 300 square kilometres search area, according to the Sydney Morning Herald.

The submersible’s first mission was aborted as the water exceeded its maximum operating depth, which is 4,500 metres; the second mission ended prematurely because of certain technical issues, which were not specified by the authorities. Both operations yielded no results.

Each mission lasts for 24 hours, as it takes two hours for the robotic submarine to reach the ocean floor and resurface, and 16 hours to search the seafloor. It uses the side-scan sonars to obtain data of the ocean floor, which will be stored in a four-gigabyte flash driver.

Four hours are needed to download the data from the submersible, which will then be analysed by officers to create a three-dimensional map.

The Bluefin-21 Autonomous Underwater Vehicle sits in the water after being deployed from the Australian Defence Vessel Ocean Shield during the search for the missing MAS flight MH370 on April 17, 2014. — Reuters pic

After detecting the sonar pings perceived to be coming from the missing flight, the Australian authorities are now more confident that they are scouring the area. The search effort now focuses on an area some 2,080 kilometres northwest of Perth. ― Reuters