Unannounced out-of-competition or out-of-season drug testing for professional athletes to detect prohibited substances.

反兴奋剂机构经常对顶尖运动员进行飞行检查。

An unannounced or surprise inspection conducted by regulatory authorities, typically in industries like food, medicine, or environmental protection.

监管部门对该食品厂进行了突击飞行检查。