How long to get down question

A query for folks here. While discussing bad things that can happen
between the chocks, I posited that it's a really bad place to be in
a medical emergency, etc. -- based on how long it takes to get on
the ground.



That brings up the question of how long that time really is....

So:
If you are at cruise in Boeing's finest at FL430 & declare an
emergency; how fast CAN you be down and stopped? (Or Airbus, for
that matter....)

a) Assuming ATC can clear a lane, I assume it's a function of how
steep a decent you can use without exceeding the max IAS. What are
the limits on speed brakes, dropping gear, etc. to dirty things ups?

b) It's a big country. I assume if you're over one coast or the
other, your decent will cover a radius sufficient to get you to a
long-enough runway. But what about over North Dakota, etc? [We'll
skip trans-ocean routes.] Will there be cases where you won't use
a max-rate decent above because there's no place within that range?

I'm looking for realistic numbers here; I welcome any data.


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