Completing the Non-precision approach as a Visual Approach

"Steven P. McNicoll" wrote in message
ink.net...

"John Clonts" wrote in message
...

The gist of my question involves either or both of these aspects:

1) Does "having the runway environment in sight...make a normal
landing"
in 91.175 mean its ok to descend below MDA, fly a couple more miles to
the
airport and then fly the pattern (circle to land), as long as the runway
is
still in sight.


Yes.


Thanks, this is as I hoped. Somewhere along the way I had picked up a
suspicion that I couldn't legally descend from MDA until aligned with the
runway.


2) Once I get to class G airspace on my approach and am clear of
clouds
in
1 mi vis, can I then descend below MDA by doing something like declaring
myself visual, contact, or canceled IFR.


No, you do not get to Class G airspace at any point at or above the MDA.



Ok, if not on this particular example, let's say it was
http://www.myairplane.com/databases/...l/BWD_vr17.pdf
where MDA is 434 haa/hat, and class G up to 700? Do any new options open
up to me once I descend out of controlled airspace at 700 agl, clear of
clouds and 1 mi vis? E.g. I could cancel IFR at that point...

Thanks again,
John

"John Clonts" wrote in message
...

Ok, if not on this particular example, let's say it was
http://www.myairplane.com/databases/...l/BWD_vr17.pdf
where MDA is 434 haa/hat, and class G up to 700? Do any new options open
up to me once I descend out of controlled airspace at 700 agl, clear of
clouds and 1 mi vis? E.g. I could cancel IFR at that point...


Yes, on this approach you enter Class G airspace before reaching the MDA.

John Clonts wrote:

snip

Somewhere along the way I had picked up a
suspicion that I couldn't legally descend from MDA until aligned with the
runway.

I've seen this recommended as a conservative rule to keep yourself safe on a
circling approach, but it's not regulatory. On some approaches it will be just
about impossible. You'll find that in order to descend using "normal" maneuvers
you'll need to start your descent before alignment with the runway.

Consider what happens if you are circling with visibility near the minimum for
the approach and don't descend from MDA until you are aligned. Will you be able
to get down?

OTOH, whenever you decide to descend below MDA, you are giving up the obstacle
protection that the approach designers built in, and substituting your own
visual obstacle avoidance. It's a tradeoff.

snip

Dave
Remove SHIRT to reply directly

"John Clonts" wrote
Thanks, this is as I hoped. Somewhere along the way I had picked up a
suspicion that I couldn't legally descend from MDA until aligned with the
runway.

This is often taught as normal procedure but (1) it's not regulatory
and (2) on most circling approaches to minimums (meaning visibility
minimums) it's either dangerous or just plain unworkable.

Look at it this way - the visibility min on most circling approaches
is 1 sm. That means that in order to keep the runway in sight, you
can't ever get more than a mile from it. That means that your pattern
will be 3/4 mile wide, max, if you're not going to exceed 1 sm from
the runway when turning base. That means that when you turn final,
you have 3/4 of a mile to get down, max. On a 4 degree glideslope
(which is about the steepest I would recommend in low vis) that's 300
ft. On a 7 degree glideslope (which is normal power-off 10:1 glide
for a light single) that's barely over 500 ft. Circling minimums are
usually higher than 500 ft. Does that mean you're going to slip down
final with a mile of vis? Are you planning on trying this trick at
night too?

Personally, I recommend starting the descent early enough that you can
maintain a constant and comfortable 3 degree descent (about 500 fpm at
90 kts) all the way to touchdown.

When the sky is blue, it's no big deal to pull the power to idle, roll
into a maximum effort slip, get down, roll out just before the flare,
and put it on the numbers. Any reasonably competent VFR pilot should
be able to do it. When visibilities drop below 2 miles, especially at
night, with rain and mist, or both, it's really not a good idea. The
subtle visual cues that form the true basis for "seat of the pants"
flying are gone. As a rule of thumb, if you wouldn't maneuver that
way in IMC, don't do it when the vis is less than 2 miles.

2) Once I get to class G airspace on my approach and am clear of
clouds
in
1 mi vis, can I then descend below MDA by doing something like declaring
myself visual, contact, or canceled IFR.

If you are actually in Class G and have 1 mile and clear of clouds,
you can cancel IFR. IMO this is a suboptimal procedure.

For example, suppose that an airplane is holding for release. The
moment you cancel IFR, the controller will release it. If you are
operating at low altitude in minimum visibility near the airport, do
you really want company?

A visual approach requires VFR minimums to be issued. I believe you
need 3 miles of visibility for that.

A contact approach is fine with 1 mile and clear of clouds, and can be
issued in controlled airspace. However, if you can see the runway,
you don't need a contact approach. On the other hand, if you can't
see the runway but can see the ground, are familiar with the area,
know where you are, and are confident you can fly to the airport
visually while remaining clear of clouds and maintaining 1 mile flight
visibility, a contact approach is the way to go.

Michael

"John Clonts" writes:

[...] 1) Does "having the runway environment in sight...make a
normal landing" in 91.175 mean its ok to descend below MDA, fly a
couple more miles to the airport and then fly the pattern (circle to
land), as long as the runway is still in sight. [...]

One thing that troubles me about this is your reference to
circling-to-land. Up here in Canada, the IFR rules say that a descent
from the MDA for circling can only be done at the "final descent for
landing" - basically for the final approach. (I believe there is a
similar restriction for straight-in landings too.)

Look at it another way. If there was no prohibition against
descending below the MDA in this circumstance, what would keep a pilot
from going to 100 AGL at the earliest hole through the clouds, and
skirting the ground all the way to the airport? You are obviously
leaving all the IAP obstruction clearance margins, but are not making
that explicit by requesting a contact approach. That doesn't sound
right.

- FChE

I'm with you on this one Frank. On a circling or straight in
approach, I dont see how a pilot can descend below the mda, to 100 ft
above the airport, level off, and still claim he is "continuously" in
a position from which a descent can be made "at a normal rate". Who
"normally" makes a descent to land at less than, say, 2 1/2 degrees?
The far could be better worded, I admit. However, I've never seen
anyone descend at say 1 degree, which an early descent well prior to a
VDP would entail.

91.175(c)Operation below DH or MDA. Where a DH or MDA is applicable,
no pilot may operate an aircraft ... at any airport below the
authorized MDA ... unless

(1) The aircraft is continuously in a position from which a descent to
a landing on the intended runway can be made at a normal rate of
descent using normal maneuvers...

my ramblings, Stan




On 18 Nov 2003 16:47:32 -0500, (Frank Ch. Eigler)
wrote:


"John Clonts" writes:

[...] 1) Does "having the runway environment in sight...make a
normal landing" in 91.175 mean its ok to descend below MDA, fly a
couple more miles to the airport and then fly the pattern (circle to
land), as long as the runway is still in sight. [...]

One thing that troubles me about this is your reference to
circling-to-land. Up here in Canada, the IFR rules say that a descent
from the MDA for circling can only be done at the "final descent for
landing" - basically for the final approach. (I believe there is a
similar restriction for straight-in landings too.)

Look at it another way. If there was no prohibition against
descending below the MDA in this circumstance, what would keep a pilot
from going to 100 AGL at the earliest hole through the clouds, and
skirting the ground all the way to the airport? You are obviously
leaving all the IAP obstruction clearance margins, but are not making
that explicit by requesting a contact approach. That doesn't sound
right.

- FChE

"John Clonts" wrote in message .. .
1) Does "having the runway environment in sight...make a normal landing"
in 91.175 mean its ok to descend below MDA, fly a couple more miles to the
airport and then fly the pattern (circle to land), as long as the runway is
still in sight.

FWIW, that's my understanding. If you have the vis and you have the
runway environment clearly in sight. Just realize that circling is
tricky, and descending then circling doesn't make it less tricky.
Also, if the cloud deck is ragged and you lose the airport, what's
your plan for how low you will go to stay visual? The "MDA"
gives you a firm floor until you have the airport and the vis.
Once you start your descent, if you're far enough from the airport
that you might realistically lose it if conditions change a mite,
what's your personal "floor" and how did you choose it?

2) Once I get to class G airspace on my approach and am clear of clouds in
1 mi vis, can I then descend below MDA by doing something like declaring
myself visual, contact, or canceled IFR.

Personally, if you have to descend below MDA to stay visual I
think I would vote for "none of the above". What if the cloud
deck is ragged and something rolls in, you have to go missed?
What if there's someone else waiting for the same approach? Or
another IFR waiting to be released?

I don't see what a contact approach gains you.

For visual approach you need 3 miles vis.

FWIW,
Sydney

"Hilton" wrote in message
ink.net...

This was (one of) your (almost) fatal mistake. At 2460' and 3 miles out,
you probably were not at 766 AGL. The 766 you see is NOT AGL as you would
first think. The 766' is the altitude above the airport elevation (for a
circling approach). Note that 1694 + 766 = 2460.

It's probable that a lot of instrument pilots do not know this.


In this case he was probably more than 766 AGL. The FAF IBAVE is right on
the river, which is probably the lowest terrain nearby.

1. You cannot roll your own visual approach. You must have a clearance and the
weather conditions must permit it, as per the guidance in the AIM.

2. What you did is more like a contact approach, which is different from a
visual approach, both, the distinctions of which are well documented and should
be part of your instrument pilot knowledge base.

3. Eventually, such early departures from the IAP not only violate 91.175, they
can eventually result in clipping a hilltop, tree, or tower.

John Clonts wrote:

I'm inbound on the final approach segment of the VOR-A approach at T82
(Fredericksburg Texas):

http://www.myairplane.com/databases/.../T82_vd_gA.pdf

At about 3 miles east of the airport I'm at the MDA of 2460 MSL ("766 AGL"),
mostly in a 700 foot overcast. Through a break in the clouds I clearly see
the airport-- the visibility is about 7 miles.

I descend 166 feet and am able to remain just under the cloud deck for the
final three miles, fly the right hand pattern for runway 14 at 600 AGL, and
land.

Was my descent to about 600 AGL (a) illegal because of 91.175c and/or some
other FAR, or (b) legal because I have now in effect "converted" to a visual
approach and/or am now in uncontrolled airspace (1 mile vis and clear of
clouds).

Mind you I'm not saying I did this last Tuesday, but I might have thought
about it if the conditions had been just so.

Cheers,
John Clonts
Temple, Texas
N7NZ

wrote in message
...

1. You cannot roll your own visual approach. You must have a clearance
and the
weather conditions must permit it, as per the guidance in the AIM.

2. What you did is more like a contact approach, which is different from a
visual approach, both, the distinctions of which are well documented and
should
be part of your instrument pilot knowledge base.

3. Eventually, such early departures from the IAP not only violate 91.175,
they
can eventually result in clipping a hilltop, tree, or tower.


Nothing in his statement suggests he departed from the IAP.