Simon and I must have attended the same school of deceleration. It's not just
CDAs but also directions like "maintain 170 kts to 5 miles" which have caused
lots of flap over speeds and unstable approaches.Â
A heavy weight arrival to Runways 25 or 24 at LAX will show you how well a
pilot understands the limits of his plane as he struggles to comply with a
tailwind and speed instructions. Ditto with Rwy 19 approaches at DCA.Â
Eric
On Tuesday, March 10, 2026 at 01:58:13 PM MDT, srbrown via Mifnet
<[email protected]> wrote:
Jack
The answer is in my opening comment, ie
 "Most commercial jet aircraft can go down, or they can slow down, but they
don't do both at the same time very well."
A continuous descent approach (CDA) often requires you to do both at some
point. It has nothing to do with what computers can do, or "think" they can do,
but simply the laws of physics. Even the smartest computer programmers and
slickest keyboard warriors on the flight deck cannot change those. Besides
which, I've never considered the Airbus flight management computers to be that
smart at calculating descent profiles accurately or reliably.
CDAs we're always a sop to the noise abatement lobbies yet I've never seen any
evidence they use less power and are hence quieter than the manufacturers'
recommended technique (my emphasis), which is to use minimum power in the
descent and then carry out any deceleration in the level segment whilst still
at idle power. I've seen that in all Airbus flight crew training manuals and
also Boeing ones. I don't know what Embraer, Bombardier or Dornier write in
theirs but I presume their laws of physics is the same.
Many pilots say CDAs are no big deal and sure, you get used to them, but
they're less safe than the manufacturers' recommended technique (funny that)
and they don't reduce fuel burn or noise.Â
I'll take the counter arguments from other pilots who I know will disagree,
possibly because they either know more physics than me or perhaps because they
have drunk more of the Korporate Koolaid than I have.Â
Simon
-------- Original message --------From: Jack Keady via Mifnet
<[email protected]> Date: 10/03/2026 19:10 (GMT+02:00) To: David Wardell
via Mifnet <[email protected]> Cc: Jack Keady <[email protected]> Subject:
[Mifnet 🛰 75627] continuous descent approaches
A respected Mif-Aviator wrote
"Don't get me started on continuous descent approaches"
Keady asks "what's wrong with them? You just dial in the target point and
desired altitude and the computer does the
rest"--------------------------------------------------------------------------
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