Nowadays most aircraft fly high, well above the clouds and weather, but their crews are still vitally interested in landing conditions at their destination, i.e. the cloud base and visibility there.

• 如今，大多数的飞机飞得很高，远在云层之上，不受天气影响，但是飞机的工作人员仍然非常关心目的地的着陆条件，也就是，云层底下的清晰度。