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Old January 3rd 07, 09:03 PM posted to rec.aviation.ifr
Mxsmanic
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Posts: 9,169
Default Confusion about when it's my navigation, and when it's ATC

Pixel Dent writes:

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.


I presume they don't say it in so many words, if they say it at all.

Small aircraft seem to be easier to get down towards the ground, or
perhaps they just don't have as far to go. In the Baron that I
prefer, there's no automation of descents, anyway. You can set the AP
to a new altitude and the aircraft will descend to it at your choice
of rates, but it's not fancy like a FMC (nor does it object if you
give it unreasonable objectives).

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.


It's hard to slow the plane down, too. With spoilers deployed on a
737-800, I can descend quickly or slow down quickly ... but not both.

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."


That would still help me, I think.

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."


Yes, I've had that. Usually the FMC decides what's best, but at least
I can override that and force a descent at a higher rate (provided
that I can tolerate the airspeed increase).

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.


I have a really hard time just understanding what they are saying
sometimes. I don't know how pilots and controllers manage to
understand each other without making mistakes. Unfortunately, the
same problem exists with virtual flight networks like VATSIM (but for
different reasons).

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