Roy Smith wrote
What
happens if I get "Cleared to the White Plains airport, via direct,
cruise 3000, frequency change approved, have a nice night"? For the
moment, let's assume it's 2:00 AM and the tower is closed.

Well, I doubt you would ever get that at HPN (even at night, the area
is pretty busy) but something like that has been known to happen at
Huntsville (UTS) where 2200 is a perfectly valid IFR altitude but
RADAR coverage below about 4000 just won't happen. I like to take
students there (assuming their airplanes are fast enough to make the
trip worthwhile) when we have a stratus layer, just so they can get
that "You are on your own" feeling, and understand what it's like to
do the full approach (and maybe the full missed approach) without
being able to talk to anyone.

Anyway, my point is that I know what it's like to be cut loose 30
miles from the airport, even if I never have heard the magic word
(cruise) because out here it is done. If you pull up the VOR-DME A
approach for UTS (http://www.myairplane.com/databases/.../UTS_vd_gA.pdf)
you will note that it has 3 IAF's. Out there, you don't normally get
a clearance to one of them - you get a clearance for the approach.
Right away that should trip an alarm - the exact route is undefined!
What this means in practice is this - the controller doesn't care.
He's perfectly happy to block out a huge chunk of airspace for you,
because nobody else wants it.

I need 1000 and 3 to fly a visual. 30 miles out, I tune in the ATIS and
hear that the weather is 2500 & 10. I'm currently in IMC. When do I
begin my descent out of 3000 for the visual? I'm guessing I can't and
must shoot an instrument approach?

Why not? Your clearance is good for any altitude between 3000 and the
minimum applicable IFR altitude. As long as you can assure that you
will comply with 91.177, you may descend at your discretion. If
you're on a random route, all you need is 1000 ft above obstacles
within 4 nm (since the terrain is not mountainous). If you're on an
airway, HPN is well within 22nm of CMK, and the MOCA's are all lower
than 3000. That's the whole point of a cruise clearance - you own
everything from 3000 on down.

OK, I decided to shoot the GPS-34
(http://www.myairplane.com/databases/.../HPN_agr34.pdf).
At what point do I stop going direct HPN and start heading to TUGME (the
IAF)?

At any point. You are the only guy around. Nobody else is using the
airspace, or you would never have gotten that clearance. Just make
sure that you can comply with 91.177 on your random route without
exceeding 3000.

And when do I begin my descent out of 3000? I'm guessing only
once I pass TUGME, so let's assume that for the moment.

Well, see above. Maybe yes, maybe no.

So, I start on down from TUGME, and quickly break out right at 2500 and
see the airport. Can I then change my mind about flying the GPS-34 and
switch to the visual? I'm guessing I can, so I make a right turn,
heading 000, to get lined up for a straight-in to 29 (my preferred
runway since it puts me closest to my parking spot).

Sounds good to me so far.

Halfway to the airport, I discover I made a poor choice in breaking off
the GPS approach because suddenly I find myself in a rain shower and
quickly after that, back in IMC at 2000. I'm not worried about terrain
in the immediate vicinity because I know I'm above anything close, but I
figure a climb back to the MSA makes sense anyway, so I do that.

No problem. MSA is 3000 and your clearance is to cruise 3000. Since
you never reported vacating 3000, it's still yours.

Now
what? If I decide to climb to 3000 and head back to TUGME for another
GPS approach, am I still operating within my cruise clearance?

Well, since you have yet to complete an approach, I can't see why not.

I guess the gist of my question is, does the cruise clearance let me fly
a single approach, or does it let me stooge around in the vicinity of
the airport trying multiple approaches until I get in or give up?

I would think the latter. Remember, you got that clearance because
you're the only idiot flying around there. You were given a big block
of airspace, and you own it until you either cancel IFR or report that
you can't get in and need to do something else.

Michael