A robotic submarine looking for the lost Malaysian jet carried out its second mission on Tuesday after its first mission was prematurely cut short due to the water's depth.

The Bluefin-21 underwater vehicle returned safely to the surface on Monday, after spending six hours scouring the Indian Ocean at depths of around 45-hundred meters in its first mission.

The Bluefin-21 underwater vehicle returned safely to the surface on Monday, after spending six hours scouring the Indian Ocean at depths of around 45-hundred meters in its first mission.

US Navy Captain Mark Matthews said the data collected by the sub was later analyzed and no sign of the missing plane was found. He added that the Bluefin-21 had to end its mission prematurely due to a programming oversight. The submersible was automatically returned to the surface after it exceeded its maximum operating depth. This was due to unexpected depths of water in the search area.

Matthews said the Bluefin only covered 30 percent of the 40 square kilometer search area initially planned for its first mission. No discovery related to the missing flight was made. But from the data gathered, searchers were able to determine that the sea floor was "relatively barren" with only a few rocks, and "the rocks are not the characteristic of what would be an aircraft".

Up to 11 planes and as many ships scoured a 62-thousand-square kilometer patch of ocean about 2,200 kilometers northwest of Perth on Tuesday. The week-long surface search is expected to end in the next two days.