Unclear Clearance

On Mon, 28 Nov 2005 06:35:53 +0000 (UTC), Daniel Roesen
wrote:

* Ron Rosenfeld :
Hm... interesting. "optimum rate consistent with the operating
characteristics of the aircraft". This is fuzzy.

Nothing wrong with giving the pilot discretion over the rate of descent.
However, there is a requirement to notify ATC if climb/descent rates will
be less than 500 fpm.

OK, that makes sense. Never heard of that requirement yet, thanks for
that. Will check our regulations here about comparable requirements.

You seem to be defining "optimum" as equivalent to "economic". I see no
such implication in the US.

Well, what other interpretations of "optimum rate of descend" would
you have in mind? If they didn't have anything specific in mind, they
could have written "any rate consistent with the operating
characteristics". Which would be kinda superfluous as you should never
climb/descend with a rate not being consistent with the operating
characteristics.


I typically climb in the neighborhood of a 1000 fpm and descend
between 800 and 1200 fpm.

If I have a descent to and cross at, I'll adjust the rate of descent
to get me down within a mile or two of the crossing point.
However if I'm kept "up there" too long, I'm not going to blow my, or
my passengers ear drums with too fast a descent.

If I'm at cruise, backing off on the throttle 5" will give me 500 fpm
while the speed stays constant. If need be I can slow down a *bit*
which will give me a steeper descent yet.

However I prefer to keep the descent to about 800 and calculate how
far out I need to start down. If I'm within a minute or two of my
limits I'll call ATC and request to start down.

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com
My definition of "optimum rate of descend" without further reference to
the parameters for determination of optimality would be something along
the lines of "the minimum rate of descend required to reach a destination
altitude complying to all altitude and speed restrictions as well as
maintaining target speed". This rate is of course a function of time,
with the result being roughly what FMS computes for VNAV as well. :-)

Well, Europe has to handle a lot fewer aircraft than does US ATC. So
maybe hat's why they need more regulations. But wait, you stated that
this is an "unwritten rule". So it's not a regulation, but merely an
expectation.

Yep. But compliance with that is quite universally as far as I'm told by
controllers. :-)

The AIM is available on line. Look at www.faa.gov for the publications.
It is not regulatory, but its procedures are generally followed.

Thanks!


Best regards,
Daniel