Plane development problems 'still to be solved'

China must resolve a host of technological and technical difficulties before it can develop a reliable short takeoff and vertical landing aircraft, aviation industry insiders say.

"STOVL aircraft use some extremely sophisticated technology and techniques," said Song Xinzhi, an aviation equipment expert in Beijing who served in the PLA air force for more than three decades.

"Even the US, which boasts the highest level of aviation technology, has spent about 20 years on its Lockheed Martin F-35B project."