It indicates that fighter pilots acquire information mostly from the OV in VFR (visual flight rules) condition and most of their visual attention is allocated to the outside world.

表明视觉飞行规则下，战斗机驾驶员主要从外景获取视觉信息，他们的大部分注意力都集中在外景。

youdao

The ban applies to private planes whose pilots do not file flight plans and who rely on visual flight rules (VFR).

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