pilot flag

例句：

1. 1. The pilot flag is a crucial part of the navigation system.
   飞行员旗帜是导航系统的重要组成部分。
2. 2. The plane's pilot flag was raised to indicate that it was ready for takeoff.
   飞机的飞行员旗帜被升起，表示飞机准备起飞。
3. 3. The pilot flag is used to communicate with other aircraft in the airspace.
   飞行员旗帜用于在空中空间与其他飞机进行通信。