In article ,
Mxsmanic wrote:

OK. But this is a bit worrisome in that the FMC apparently already
calculates the optimal descent. If I can't start down in time, I may
not be able to make the other altitudes in the route without holding
or some other diversion to provide more time to descend. For some
reason, the FMC seems to be optimistic about how quickly it can force
the aircraft down. I have to deploy spoilers a lot, and that's even
when the descent starts on time.


Well, I don't fly airliners. I fly a single engine prop that rarely sees
anything above 9000'. That being said I fly a lot of IFR and have never
heard a pilot say "Center, my FMC says I need to start descending now."
Somehow in real life they manage it.

If you're having trouble descending fast enough in the Sim maybe you
just need to slow down the plane to give you more time.

Anyway, so I can just say "request descent" when I'm ready to start
down?

Sure. But even if it's approved that doesn't mean you can just descend
at will to the airport. What you're likely to get is something like
"AB123, descending and maintain one two thousand expect lower in 20
miles."

In general what happens is you gradually get "stepped down" in altitude
via a series of descents as you get closer to the airport until the
final approach controller gets you down to whatever altitude is needed
to start your approach (usually something like 2000' AGL). Once you're
given each new altitude assignment the controller really wants you to
hurry down to the next altitude and level off there so you get out of
the way of other traffic. At times you'll even get requests like "AB123
I need best speed down to one five thousand, I have conflicting
traffic."

To really get a feel of how this all works I'd suggest you go to one of
those live atc sites and listen to an approach controller. You'd be
amazed how much you can learn listening to one for a half hour. At first
it will seem chaotic and then you'll realize there are patterns to what
he's doing with the planes.