Visitors gather to watch a helicopter at the Tianjin International Helicopter Exposition in a helicopter base of Aviation Industry Corporation of China in the Airport Area of China Pilot Free Trade Zone of Tianjin, China, Sept 9, 2015. The Tianjin International Helicopter Exposition kicked off in Tianjin on Sept 9. A total of 366 companies from around 20 countries and regions will take part in the event. As many as 56 helicopters will be on display during the exposition. [Photo/Xinhua]