Cloud distance and mist layers
The VFR rules in SERA.5001 talk about "cloud distance" for different airspaces.
How about mist layers, do these count as cloud as well?
For instance, last week in Southern England there were relatively thin (~1000 ft) mist layers that allowed for a perfectly good vertical visibility, but once you entered them the flight visibility was _greatly_ reduced.
The other thing is, flying into a cloud under VFR is an obvious no-go. But VFR pilots routinely punch through mist layers, despite encountering borderline or sub-VFR flight visibility.
Raising another question: How do you estimate flight visibility in mist layers and thickness without "having a peek" and possibly entering IMC flight visibility (and the danger of a collision)?
Michael