An aviation policeman pilots the police helicopter in a routine patrol aviation for the tightening the orderly security guarding for the grand celebration of the National Day, in Zhengzhou, central China's Henan Province, September 23, 2009. [Xinhua]

Two aviation policeman pilots demonstrate the formation in air prior to their helicopter routine patrol aviation for the tightening the orderly security guarding for the grand celebration of the National Day, in Zhengzhou, central China's Henan Province, September 23, 2009. [Xinhua]