First "real" hold (long)

"Barry" wrote
A lot of pilots don't
understand that the rule about going down to 100' on the approach lights
doesn't remove the visibility requirement. If you see only a few approach
lights at DH, you almost certainly do not have the required visibility, and
should go missed.

I don't agree with that at all.

As you mentioned above, slant visibility is not at all the same as
ground visibility. If it were, I would agree. However, in my
experience slant visibility is almost always much worse than ground
visibility (RVR) with the sole exception being ground fog.

At Pensacola, the minimum RVR is 2400 ft. I've seen it as low as 1800
ft for Cat I approaches.

From 200' and assuming no displaced threshold and a typical TCH of 50
ft (as is the case for PNS) it's just under 2900 ft from airplane at
DH (200 ft) to threshold. So of course if you can see the threshold,
you have vis - but if you can't, that doesn't necessarily mean you
don't.

If you see just a few lights from 200 ft, that can mean different
things. Sometimes it means that ground visibility is below mins, and
then you do need to miss. However, more often (at least in my
experience) it means that the VERTICAL visibility is poor - meaning
you can see fine from 100 ft or so, but can't see much of anything
from 200. I've personally experienced approaches where at 200 ft I
could see just a few lights, but at 100 ft I could see halfway down
that (6000+ ft) runway.

Granted most of my IFR experience is limited to the Gulf Coast, but on
the Gulf Coast this situation is VERY common - and very short lived.
Give it an hour, and it almost always clears to VFR.

Michael