China's first homegrown aircraft carrier looks set to begin its maiden sea trials after pictures appeared online on Monday of it being towed from its berth in the northeastern port of Dalian. The sea trial of the Type 001A carrier, which coincides with the PLA Navy’s 69th anniversary, is expected to be limited in scope and duration but analysts said it had a symbolic importance as China sought to highlight the advances it had made as a nautical power. The Liaoning Maritime Safety Administration had announced on Friday that three areas in the northeastern Bohai and Yellow seas would be cordoned off for military activity between April 20 and 28. The carrier left its berth in Liaoning province with the assistance of tugboats on Monday at about 10am, according to a photo circulated on Twitter by the official party mouthpiece People’s Daily . Song Zhongping, a Beijing-based military expert meteorological conditions would be a key factor in determining the success of the trial. “The area being cordoned off for the trial is quite narrow and the time period is quite short,” said Song, “Being the first trial, it has symbolic and has important political significance, so the military has to make sure that nothing will go wrong … the coming few days starting from today [Monday] is good timing.” China and Taiwan air forces trade videos warning each other of willingness to protect interests Song said this week’s trial would mainly test the ship’s propulsion and communication systems. Other systems such as its electronics and weapons will be tested in subsequent trials in the near future. A naval source earlier told the South China Morning Post that the maiden trial may just involve turning a circle in Bohai bay and making sure there were no leaks below the waterline. A main engine run was conducted last week and was again on Monday, according to Beijing-based military expert Zhou Chenming. The Type 001A’s propulsion system uses eight steam turbines – a design copied from the Soviet TB-12 engines used by its sister ship, the Liaoning. “Like the Liaoning, the Type 001A is also using bunker oil that can’t be burned completely, so we saw the ship emitting black smoke when its propulsion system was tested today,” Zhou said, adding that a similar phenomenon was seen on April 17 when the giant ship’s engines were first tested. China’s new aircraft carrier may start sea trials this week “But black smoke just appears in the first 10 minutes of the engine test, then it will return to normal.” Zhou said the maiden sea trail on Monday would see the new carrier turn a circle within Bohai, but it could remain at sea until April 28 depending on the weather and ocean conditions. Zhou said the new carrier would be tested for between six and 12 months in different waters and different ocean conditions before it was handed over to the navy. “More equipment on the ship will be tested in the future, including weapon systems, its radar, damage control, electronic systems, and so forth.” The new warship is an upgrade to the Type 001 Liaoning, China’s only operational aircraft carrier, a refitted Soviet-era Admiral Kuznetsov-class vessel. It took nearly six years for the Liaoning to become fully combat-ready after it entered service in 2012. But Song said that the experience gained would allow the new vessel to become combat-ready within about two years.