China's aircraft carrier leaves port on Tuesday for a second round of sea trials.

BEIJING - China's aircraft carrier left port on Tuesday for a second round of sea trials, which are likely to include test flights from the refitted vessel.

"Carrier-borne aircraft will possibly take off and land on the vessel for the first time, as these moves cannot be done in dockside tests," said Yin Zhuo, a retired navy rear admiral and military expert.

He said an important component of the trial will be to test the steel cables used to catch the aircraft and decelerate them upon landing. The cables can bring an aircraft from going 300 km/h to a full stop in just a short distance.

Catapults may also be tested to see whether they can help propel various types of aircraft into the air.

"Of course, another task is to test communication between the carrier and aircraft, and whether the navigation system will lead the aircraft to their designated locations," Yin added.

Media reports have claimed that the deck-based J-15 fighter will be deployed on the carrier, but this has not been confirmed by the military.

The Ministry of National Defense said in a statement that the steam-powered aircraft carrier has completed all refitting and testing work as scheduled after its first sea trial in mid-August, and was heading back out to sea for additional scientific research and experiments.

The carrier was originally meant for the Soviet navy, but the construction on it was halted as the Soviet Union collapsed in 1991. Engineers in the Ukraine disarmed it and removed its engines before selling it to China in 1998.

The vessel, an Admiral Kuznetsov class aircraft carrier measuring 304.5 meters long, and having a displacement of 58,500 tons, has been refitted for research and training in China.

Shi Yinhong, an expert on international affairs at Renmin University of China, said the announcement of the vessel's second sea trial is mainly aimed at letting the Chinese people know how preparations for the carrier are going.

"The people are very interested in the carrier, and the military is telling them about its new achievements during its lengthy preparation," he said.

China will be the last permanent member of the United Nations Security Council to operate a fully functioning carrier once the vessel is delivered to the navy of the People's Liberation Army.

The United States, Britain, France, Russia, Spain, Italy, India, Brazil and Thailand operate 21 active aircraft carriers.

The US alone has 11.