MELBOURNE - The underwater search for Malaysian passenger plane MH370, which mysteriously vanished six months ago resumed on Monday, the Australian Transport Safety Bureau (ATSB) which leads the mission said.

The GO Phoenix, a Malaysian government contracted ship, is the first of three vessels that arrived in the vast search zone and the fleet will spend around a year to hunt for the wreckage of MH370 in the area about 60,000 square kilometers.

One of the largest international aviation searches in history had been underway after MH370 disappeared with 239 people on board during its March 8 flight from Kuala Lumpur to Beijing.

However, the multinational search team had to stop the hunt after nearly two months of fruitless work and the related countries began to map the sea floor which was crucial to continue the underwater mission.

According to the plan, GO Phoenix will use an underwater sonar device called towfish to operate 100 meters over the seabed. When the device detects any suspicious wreckage, the ship would put down highly sensitive camera equipments to film it and decide whether it belongs to MH370 or not.

GO Phoenix would stay in the mission area for 12 days before heading to the Australian coast for refueling and supply. Two other ships provided by Dutch contractor Fugro would join the GO Phoenix later this month.

In an interview with the local ABC news, ATSB Chief Commissioner Martin Dolan expressed cautious optimism about the search, saying "all we want to indicate to everyone is we're cautiously optimistic in the course of a year we'll locate the missing aircraft."

"We don't really have any sense of when in the course of that year we're likely to find something," he added.

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