"Mxsmanic" wrote in message
Now, my question is this: If the FMC has a programmed descent in its
route, do I let the FMC start the descent where it sees fit, or do I
force the aircraft to maintain FL290 until ATC explicitly clears me
for my own navigation or for a lower altitude?

The profile in the FMS is for efficiency and does not take other traffic
into account. You must wait until ATC explicitely clears you to another
altitude. If you are about to pass the FMS's descent point, politely prompt
ATC for a lower altitude. Going into LAS, you very well may get vectors off
the planned route so that ATC can adequately space the arrival traffic (in
the real world).

And if ATC's last
instruction had simply been "resume own navigation" or "proceed as
filed," would that mean that I'd be free to begin the descent whenever
the FMC (or I) decides it's best?

No. That would be for lateral navigation only unless explicitely cleared for
different altitudes. Here is an example that one of my colleagues recently
received counseling about. He was cleared via the KORRY 3 arrival into KLGA.
He started to descend according to the profile. ATC asked why he was
descending and to call a number after landing (not good). He was cleared via
the KORRY 3, not cleared to descend via the KORRY 3. Slight difference, but
very important for traffic seperation.

In situations where I can begin the descent at my discretion (assuming
that own navigation implies this), should I tell ATC that I'm leaving
my cruise altitude?

Yes, the Aeronautical Information Manual states that a pilot should advise
when leaving an altitude.

If the FMC has a continuously changing estimate
of lower altitudes in the descent profile, what should I give as my
target altitude? The next fix that has a specific altitude? (Such as
a fix in the arrival procedure)

Yes.

Climbing I think I understand. If I'm told to resume own navigation,
or cleared as filed in the first place, I climb per my flight plan/FMC
profile. If ATC says maintain X, I stay at X until ATC tells me to
resume own navigation or instructs me to change altitudes. But the
descent part still has me a bit confused.

Query ATC for the assigned altitude so that both of you are on the same
page. Climbs are the same as descents. 'resume own navigation' is for
lateral flight. Don't climb unless expicitely assigned a new altitude by
ATC.

D.