Passengers check in for flights at the Guangzhou Baiyun International Airport in Guangzhou, capital of south China's Guangdong Province, June 6, 2012. China Southern Airlines opens a direct air route linking the southern China metropolis of Guangzhou and London on Wednesday. This is the first direct air route linking the two destinations with three two-way flights a week on the line. [Xinhua/Jin Liangkuai]