A pilot assigned to an aviation brigade of the air force under the PLA Western Theater Command climbs into the cockpit of his J-11 fighter jet prior to a combat flight training exercise at low temperature after snowfall on February 23, 2018. Photo:eng.chinamil.com.cn

A J-11 fighter jet attached to an aviation brigade of the air force under the PLA Western Theater Command takes off for a combat flight training exercise at low temperature after snowfall on February 23, 2018.Photo:eng.chinamil.com.cn

A J-11 fighter jet attached to an aviation brigade of the air force under the PLA Western Theater Command takes off for a combat flight training exercise at low temperature after snowfall on February 23, 2018.Photo:eng.chinamil.com.cn

A J-11 fighter jet attached to an aviation brigade of the air force under the PLA Western Theater Command flies over snow-capped mountains to a designated airspace during combat flight training at low temperature after snowfall on February 23, 2018.Photo:eng.chinamil.com.cn