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Lorn, easy enough to ask for a block to a lower level for descent. If the airspace is clear, you can then descend at a more economical 300-400 fpm. This efficiently converts potential energy (altitude) into increased speed and/or reduced power generation for the same speed. If you are high up and do a 2000 fpm descent, you are effectively wasting most of the energy you expended climbing to the higher altitude....it's like slamming on the brakes of your car when you are doing 70 mph hour versus coasting are little cost to a lower speed---both will get you there and you'll come to a stop, but the cruise descent is much more efficient.
And, as noted, you can cancel IFR and advise that you are descending to some altitude. ATC has their business to take care of...and we have ours.
Chuck Jensen
-----Original Message-----
From: Lancair Mailing List [mailto:lml@lancaironline.net]On Behalf Of
Lorn H Olsen
Sent: Saturday, November 15, 2008 10:07 AM
To: lml@lancaironline.net
Subject: [LML] Re: Preferred Decent Angle (LIVP) for Arrival (using
Chelton)
Jeff,
When I flew a C340 I did most of my descents at 1,000 fpm, when
possible. Ask ATC for lower when you are ready to descend. Most of the
time they will give you the lower altitude. Sometimes, they are not so
agreeable. Last month I was told to be "at or below" an altitude that
would have required a 6,000 fpm descent. When I said that I couldn't
do that, the controller ask me to do a 180. In this particular case, I
told the controller that I knew a trick and cancelled IFR.
I know that if you can't maintain a 500 fpm climb, you need to report
that to ATC. I believe that is the same for the descent.
In my 320, I set my 396 to descend me at 400, 500 or 1,000 fpm
depending on winds aloft. Sometimes I want to stay at 16,000 feet
longer for the tailwind. Sometimes I want to make use of the potential
energy for the speed. I change the descent profile on most of my
flights.
Your question of "what is the most common descent angle" is like
asking, "what is the most common wind aloft". If possible you should
change your descent rate based upon; 1) How hard is the rate to
change? 2) How busy is the arrival airport?, 3) How controlling are
the arrival controllers? and 4) How long do you want to stay at
altitude?
Now for my curiosity, how easy is the descent rate to change on the
Chelton. On my 396 I have about 11 keystrokes to get to the VNAV rate.
Lorn
> From: "Jeffrey Liegner, MD" <liegner@embarqmail.com>
> Date: November 14, 2008 7:09:41 PM GMT-05:00
>
> When anticipating a descent into the arrival airport, often ATC and
> I don't agree on the best solution. They have their traffic
> separation issues and sector hand off requirements, so I
> understand. But this leads to the question of what is the most
> common descent angle that pilots are programming into their Cheltons.
> .
> .
> Thanks.
>
> Jeff L
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