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

"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.

Well, maybe you don't have it at 200', but you might at 100'. In my
experience, horizontal visibility can vary a great deal with the last couple
hundred feet of altitude. That certainly is true when a ground fog is
lifting, as was the case at PNS last Sunday.
--
Dan
C-172RG at BFM

Ask for 6 mile legs.

"Dan Luke" wrote in message ...
"Roy Smith" wrote:
I suppose so. I always have this feeling my old CFII is sitting in the
right seat, shaking his head when I don't do something "by the book."

Single-pilot IFR is all about task prioritization. Take care of the
important stuff, and don't waste time on the **** that doesn't matter.
As long as you stay in the protected airspace, nobody cares what your
holds look like, or how perfectly timed the legs are.

Save the mental effort for important things like making sure your fuel
planning is right, getting a good picture of the weather from flight
watch so you know when to divert (and where), and briefing the approach
you're about to fly.

Good points, I know, but after 20 minutes of holding you've done all that
and you'e really in need of something else to do! The PNS controller was
doing a good job of updating aircraft on the freq. about conditions at
nearby airports, but calling FW would have been a good idea.

"Dan Luke" wrote in message
...

"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.

Well, maybe you don't have it at 200', but you might at 100'. In my
experience, horizontal visibility can vary a great deal with the last
couple
hundred feet of altitude. That certainly is true when a ground fog is
lifting, as was the case at PNS last Sunday.

Yup. Also, a ragged ceiling at 200' might block your view past the approach
lights. But when you get completely below the clouds, the visibility might
be fine. I've had approaches like that.

--Gary

--
Dan
C-172RG at BFM

On Mon, 04 Oct 2004 07:57:31 -0400, Roy Smith wrote:

In article , Scott D.
wrote:

What made matters worst, was the fact that we had around a 42 knot
tail wind on the outbound leg, which made for a 15 second outbound
just for a 1 min inbound. Talk about work!

In a situation like that, you can make life easier on yourself by asking
for longer legs.

You know, honestly that never really occurred to me. That was about
the first real hold that I ever had to do in about 5 years of flying
so my first thought was, am I actually doing this correctly But
that is something to think about if I ever had to do that again.

Today, I was stuck at SAF waiting for the fog to burn off because we
had some avionic/electrical issues on the plane I was flying and I
told my boss that I was not going to fly out of their IFR with some
known issues and that we were going to wait till it went VFR, but in
the mean time, We were out on the flight line when we heard a jet
going missed, we could hear him but could not see him. Then about an
hour later here he came and went again. I knew his pain and felt
sorry for him. Then about another hour later, the fog had lifted
enough and he was able to set it on the ground. It was a Challenger.
I talked to the pilot and asked him how long he had held and he said
that was the longest 2 hours he had ever lived. He said he had enough
fuel for 1 more hour but he didn't thing that "HE" would have made it.


Scott D.

"Gary Drescher" wrote
Yup. Also, a ragged ceiling at 200' might block your view past the approach
lights. But when you get completely below the clouds, the visibility might
be fine. I've had approaches like that.

I have too - but never on an ILS. Just out of curiosity - where have
you seen ragged but defined sub-200 ft ceilings? I'm not questioning
your observation, merely wondering whether there is a part of the
country where they are more common.

My experience more closely parallels Dan's - but given that we both
fly on the Gulf Coast, no surprise there.

I wonder if anyone has ever made a study of low altitude weather. It
would sure be useful to the beginning instrument pilot, especially
given how few training approaches are typically flown to actual mins.
I find if I can get a student 3 actual approaches to near-mins over
the course of training, that's pretty good. A good text explaining
what to expect would sure be a good supplement.

Michael

"Doug" wrote in message
om...
Ask for 6 mile legs.

You wouldn't need a plane if you had 6 mile legs.

Paul

"Michael" wrote in message
m...
"Gary Drescher" wrote
Yup. Also, a ragged ceiling at 200' might block your view past the
approach
lights. But when you get completely below the clouds, the visibility
might
be fine. I've had approaches like that.

I have too - but never on an ILS. Just out of curiosity - where have
you seen ragged but defined sub-200 ft ceilings? I'm not questioning
your observation, merely wondering whether there is a part of the
country where they are more common.

I encountered those conditions one day at FRG (Long Island, NY; 250' DH).
The weather was quite unusual though, with lots of low-level turbulence and
windshear. On my first try, I had to go missed--the only time I've done that
(other than for practice) in my 25 IMC approaches so far.

--Gary

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.

Well, maybe you don't have it at 200', but you might at 100'. In my
experience, horizontal visibility can vary a great deal with the last couple
hundred feet of altitude. That certainly is true when a ground fog is
lifting, as was the case at PNS last Sunday.

OK, but 91.175(c)(2) says you must have the required flight (horizontal)
visibility to coninue the approach below DH, not just at 100' or at landing.

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.

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.

But as I replied to Dan Luke, neither the visibility at 100' nor the ground
visibility can replace the requirement for flight visibility to continue the
approach below DH. I've always interpreted 91.175(c)(2) to mean that you must
have the required visibility at all times below DH. Is there a reference that
contradicts this? In the case you describe, you almost certainly do not have
the required forward visibility at all points along your path. One exception
I can think of would be near the edge of a sloping cloud, but this must be
rare.