Bering
Bristow offshore take-off minima in UK North Sea is 800m visibility.
How is this measured offshore??
On ETAP with no other rigs close by, or buoys at set distances, or a standby boat that could give you visibility it was impossible to give an accurate visibility it was pure guesswork. I asked for the rig weather station to be modified to give visibility (as the 40s did) but it was never done in my time
HF