Able Seaman Boatswains Mate Rory Dow heads towards a floating object sighted from aboard a Rigid Hull Inflatable Boat searching in the southern Indian Ocean for the Malaysian Airlines flight MH370 in this picture released by the Australian Defence Force April 2, 2014.[Photo/Agencies]

Urgent search for missing jet

Searches for the missing Malaysia Airlines flight MH370 came at a critical time, as they must gear up their hunt for the aircraft's black box.

It is presumed that the black box will run out of battery power around April 7, or April 12 at the latest, and its signal will then vanish.

Malaysian Prime Minister Najib Razak is scheduled to visit the western Australian port city of Perth on Wednesday for the ongoing search for missing Malaysia Airlines Flight MH370.

Meanwhile, the designated search area for Wednesday is closer to the western Australian coast, now about 1,490 km northwest of Perth, according to the latest information from the Australian Maritime Safety Authority (AMSA).

In parallel, the intensity of the hunt keeps increasing. British Ministry of Defense (MoD) said Tuesday that Royal Navy submarine HMS Tireless has arrived in the southern Indian Ocean to help with the search.

With its advanced underwater search capability, HMS Tireless, a Trafalgar Class submarine, will be able to contribute to the efforts to locate the missing plane, the MoD said.

The MoD added that, HMS Echo, a British Royal Navy coastal survey ship, is also due to join the hunt soon for the ill-fated Boeing 777 jetliner, which disappeared early March 8 while carrying 239 people -- including 154 Chinese passengers -- from Kuala Lumpur to Beijing.

Seven Chinese vessels and two Chinese IL-76 planes are involved in the search west of Perth, and a three-ship Chinese naval flotilla previously deployed in the Gulf of Aden for escort missions has teamed up with a Chinese patrol vessel to search for the missing plane south of Australia's Christmas Island.

Despite massive multinational efforts, no hard evidence has so far been acquired about the whereabouts of MH370.