Robotic submarine completes 7th mission to locate missing jet

A robotic mini-submarine deployed to unprecedented depths has searched approximately 50 per cent of the focused underwater area of the Indian Ocean floor, as it ended its seventh mission on Sunday with still no sign of wreckage of the missing Malaysia Airlines plane

Autonomous underwater vehicle Bluefin 21, a US navy probe equipped with side-scan sonar, has focused the search on an area where four acoustic signals were detected that led authorities to believe that the missing Malaysia Airlines plane's black box may be located there.

"The Bluefin-21 AUV completed mission seven in the underwater search area. Bluefin-21 has searched approximately 50 per cent of the focused underwater search area to date," the Perth-based Joint Agency Coordination Centre said in a statement.

"No contacts of interest have been found to date," said the statement, as the search entered its 44th day on Sunday. The air, surface and underwater search is focused on footage taken by a US navy deep sea drone, which has narrowed its target range to a tight 10-km circle of sea floor.

The current underwater search is centred on an area where one of four acoustic signals believed to be from the plane's black box recorders was detected on April 8. The remote controlled submarine is now in its eighth deep sea mission with no sign of wreckage so far. Up to 11 military aircraft and 12 ships will assist in the search for missing flight MH370.

"Today the Australian Maritime Safety Authority has planned a visual search area totaling approximately 48,507 square kilometres, across two areas," the statement said.

The Beijing-bound Malaysia Airlines flight MH370 -- carrying 239 people, including five Indians, an Indo-Canadian and 154 Chinese nationals - had mysteriously vanished on March 8 after taking off from Kuala Lumpur.

The mystery of the missing plane continued to baffle aviation and security authorities who have so far not succeeded in tracking the aircraft despite deploying hi-tech radar and other gadgets.

Malaysian Acting Transport Minister Hishammuddin Hussein has said the search is at a "very critical juncture" and asked for prayers for its success. He also said the government may consider using more AUVs in the search.

Photograph: US navy photo by Mass Communication Specialist 1st Class Peter D Blair/Handout/Reuters