In Flight Visibility
In reality, In-Flight Visibility (IFV) would need to be taken into account. IFV is the visibilty required to maintain sight of the airport in a rate 1 turn. This is assumed to be 3000 metres. To calculate required in-flight visibilty , multiply the aircraft's manoeuvring speed in knots by 20 e.g 150 kt x 20 = 3000 metres in-flight visibilty.
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