You can find the full overview of EASA’s calculation model here:
What is VLOS?
In the open category, you must operate your drone so that you can clearly see the drone and its surroundings at all times, as well as its direction and ability to avoid hazards. This is referred to as VLOS – Visual Line of Sight.
The VLOS requirement applies to all drone pilots. Whether you operate in the open or specific category, and regardless of whether you have a drone certificate or not, you must know your maximum VLOS distance.

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