Under dark clouds, Chinese naval vessel Jinggangshan is surging through violent storm and roaring waves in the southern Indian Ocean to hunt missing Malaysia Airlines Flight MH370.

The amphibious landing ship is just one of the seven Chinese ships scouring waters west of Australia's Perth for the ill-fated Boeing 777-200, which suddenly vanished from radar on March 8 with 239 people on board.

On Monday morning, the log indicator in the chart room showed that the ship has sailed 7,500 nautical miles (14,000 km) since it joined the search mission 23 days ago.

With 154 of the 227 passengers being Chinese, Beijing has launched an all-out search and rescue mission involving air, sea and underwater forces. The Chinese navy has so far dispatched six aircraft and nine various warships in seven sorties, including amphibious landing ships, supply ships, missile destroyers and frigates.

"From the urgency of the mission, the mutability of available information, and the synergy of all contingents, this search and rescue endeavor is very similar to a real combat operation," said Wang Yongxiang, commander of the Chinese navy's maritime search mission.

The Jinggangshang, which cruised into the Indian Ocean after plowing waters in the Gulf of Thailand, Andaman Sea and Sumatra, and other Chinese naval vessels took part in the non-combat military operation in a high morale for a real sea battle, Wang added.

For normal maritime search operations, the search scope at sea will be gradually narrowed down once an area is locked. But due to uncertain information on flight MH370's whereabouts, Chinese and foreign vessels are continuously expanding their search areas.

Just as Mark Binskin, vice chief of the Australian Defense Force, put it, "We are not searching for a needle in a haystack but still trying to define where the haystack is."

The distance and time for this mission are growing beyond expectations, said Yang Liu, a marine in charge of the lookout post.

"Frankly speaking, we feel tired," he said. "But we must keep holding on. Who knows when the target will appear before our eyes?"

Since joining the search mission, the Jinggangshan has been working round the clock with all its monitoring systems running in full swing, including radar, infra-red and optoelectronic searching devices. Two helicopters aboard the vessel also carried out air search.

The high intensity and complexity of the mission is a severe test to both the ship and its crews.

On Monday, the weather at the new target sea area of 72,000 square nautical miles, located at 28-34 degrees south latitude and 92-96 degrees east longitude, was rough with wild winds and huge waves, thus offering poor visibility.

"Today's search will be led by the ships at sea, but we'll also get ready for air search if needed," said Wang Jingbin, deputy chief of a helicopter regiment of the South Sea Fleet.

The Chinese navy has employed nearly all its means to hunt all possible traces of MH370, including floating objects, oil slicks and life jackets.

Yuan Guangxue, a marine who participated in earthquake relief efforts in China's southwestern province of Sichuan six years ago, said that no matter how complicated and arduous the mission is, the Chinese rescuers will not give up any hope.

"That disaster relief mission let me keep a principle in mind: We should never stop trying easily," he said.

(Xinhua News Agency March 31, 2014)