![WZ-9 helicopters fly at night(6/6)](http://www.ecns.cn/hd/2017/04/19/a704e214093544c680908c881ecf3a45.jpg)
A cadet assigned to a helicopter group of the PLA Air Force Xi'an Flight College checks the airborne equipment in the cockpit of a WZ-9 helicopter prior to a night flight training exercise at a military training base in southwest China's Sichuan Province in mid-March, 2017. (Photo/81.cn)