When descending from cruise altitude using managed descent you have to set each constraint in turn.
With a rnav approach you set the lowest altitude (eg 200 feet above ground) and the plane descends automatically, each waypoint in turn. And this can be over several thousand feet (eg rnav in Queenstown, NZ).
Is there a good reason why descending from cruise altitude can’t be the same?
Richard
From cruise ALT, before TOD, I set the Final Approach Fix altitude, and at TOD push that so that the Fenix manages the descent.
The Fenix descends quite happily, respecting any and all constraints quite the thing, until the FAF where APPR comes in.
Doesn’t matter which Approach type.
How is the Final Approach Fix altitude set in the MCDU? Is this done by clicking on a waypoint at the multifunctionsbutton right of the waypoint and entering an altitude?
The FAF should already be determined in the database for your programmed/chosen Approach. When I say “I set the Final Approach Fix altitude” this means I dial in the altitude in the FCU.
So, say I’m cruising at 35,000ft. The TOD is coming up ahead.
Looking at my charts or MCDU I see that the Final Approach Fix states 3,000ft.
I set the ALT to be 3,000ft in the FCU and when passing the TOD marker, I “push” the ALT button to tell the A320 “hey, you can now descend, and you work out how fast or slow we go down”.
The A320 will respect any altitude and speed (if you’re using Managed Speed, of course) magenta constraints that are in the MCDU plan.
Eventually we get to the FAF waypoint, and to give the A320 permission to go lower to land, we need to use APPR and be lined up (and tuned in for LOC/ILS) to capture the Glideslope (ILS) or Glidepath (RNAV).
This all, at the moment, assumes you’re not using ATC.
For ATC you’d be dialling in each ALT, speed or HDG instruction as given by a controller (and probably using Open Descent too)
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