minimum night altitude

例句：

1. 1. The aircraft's minimum nightaltitude is 500 meters.
   飞机的最低夜间高度是500米。
2. 2. The pilot must maintain a minimum nightaltitude of 300 feet abovethe ground.
   飞行员必须保持至少300英尺
3. 3. Due to poor weatherconditions, the flight was forced to descendto a minimum night altitude.
   由于天气条件恶劣，航班被迫降至最低夜间高度。