Some 44 per cent of mainland airports are operating at or above their full capacity while a further 34 per cent will reach full capacity by 2015. Diao Yonghai , a deputy director-general of the General Administration of Civil Aviation of China's (CAAC) airport department told a conference in Shenyang , Liaoning province , yesterday that about 60 airports had already reached their full capacity and 13 of those had to cope with air traffic above their maximum capacity, Xinhua reported. A further 36 airports would meet their full capacity by 2010 while 11 more would face the same problem by 2015, he said. Mr Diao warned that the mainland's airports would struggle to cope with growing air traffic. There were 137 airports on the mainland last year, according to the CAAC. China is expected to have a fleet of 1,580 planes by 2010, he said. Building airports in a more resource-efficient way and making them more environmentally friendly were also high priorities, he said, adding the industry was also moving towards more cost-efficient operation. The airport-building frenzy seen on the mainland in the 1990s attracted strong criticism for wasting resources as cities scrambled to build large and expensive facilities. Mr Diao said the new airports would have more advanced facilities and more runways to meet the increasing air traffic. According to the CAAC website, the busiest airports are Beijing, Guangzhou and Shanghai. Gao Hongfeng , a vice-director of CAAC, said earlier that Beijing Capital International Airport had only been designed to handle 35 million passengers a year but had to cope with 41 million passengers last year. There were more than 60 aircraft movements an hour, he said. Officials say the number of mainlanders travelling by air has doubled in the past five years and is expected to do so again by 2010.