PERTH, Australia, April 15 -- The autonomous underwater vehicle Bluefin-21, which was deployed on Monday afternoon for its first underwater search mission, has encountered unexpected depth of waters and ended its mission prematurely, U.S. Navy Captain Mark Matthews told Xinhua on Tuesday.

In an exclusive interview with Xinhua, Matthews said the Bluefin was launched at 5:20 p.m. local time (0920 GMT) Monday evening and was recovered at 1 a.m. (1700 GMT) on Tuesday.

"The area where the Bluefin was programmed for searching ranges from a depth of 4,200 to 4,400 meters, according to the chart. How the Bluefin was programmed was to maintain an altitude over the sea floor of 30 meters. Unexpectedly, we encountered an area that was deeper than 4,500 meters and if the Bluefin would have followed its directions, it would have exceeded its maximum operating depth," Matthews said.

The Joint Agency Coordination Center said on Tuesday that after completing around six hours of its mission, Bluefin-21 exceeded its operating depth limit of 4,500 meters and its built-in safety feature returned it to the surface.

Of the 40 square kilometers of search area initially planned for its first mission, 30 percent had been covered. But no discovery related to the missing Malaysian flight MH370 was made.

"Data from about 30 percent of the search area has been downloaded and reviewed. There was no sign of any evidence of the aircraft in that portion of the search area," Matthews said.

He said the Bluefin has been reprogrammed with better instructions to prevent a similar mission abort and to keep it operating within its operating limitation.

"It will be put back into the water again later Tuesday when the sea state and wave height comes down to allow the safe deployment of the system," he said.