"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