A330 - How to get autopilot to follow waypoint altitude constraints?

User Support Hub Aircraft & Systems
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1

I set cruise altitude to 35,000… FPLAN has all the waypoint speed/altitude data, INIT complete for fplan/fuel/weight/wind/takeoff. (No waypoint constraints exceed cruise altitude)

I set autopilot to managed mode on alt/hdg/spd and it follows the speed/heading constraints of the flight plan, but it WON’T follow waypoint altitude constraints and they dont show up in magenta on the primary flight display. What the AP does do, is go straight to the designated cruise altitude while ignoring waypoint altitude constraints.

What am i missing? I’ve tried at least 10 different flight plans. (simbrief)

2

In managed mode, the autopilot will never descend below your set altitude, so if you leave it at 35,000 you will never descend. In order to descend, you must change your set altitude to the lowest altitude you want to allow.

So for example, you are cruising at 35,000 and your set altitude is also 35,000. You are directed by ATC to descend to 15,000 feet. Here is how:

  1. First, change your set altitude to 15,000 feet. If you do nothing else, your aircraft will wait until it reaches your TOD (top of descent) then automatically start descending down to an altitude not lower than 15,000 feet.

  2. If you are not at your TOD OR if you want to immediately descent, pull the altitude know to switch from Managed to Open descent. The aircraft will descend immediately but again not to a lower altitude that you set.

Change your set altitude to allow the aircraft to continue descending.

3

A few things I should’ve clarified:

  • The problem I’m referring to is during ascent to TOC. Let’s say cruise is set to FL390 with 5 waypoints prior to TOC, each with incremental increases to altitude below cruise level. (IE 5,000, 8,000, 17,000, etc). The autopilot will ignore the constraint of the waypoint altitudes and go straight to FL390.
  • I set the altitude in the flight plan and on the autopilot altitude knob.
  • ATC doesn’t talk to me. I’m assuming it’s because i’m using simbrief and not the EFB
4

You may not be in Managed mode. You may need to press the altitude knob to enable Managed Climb. There should be a filled dot/circle next to your altitude.

Could also be that the flight plan didn’t import constraints. Check the FMS vertical revisions to see if the constraints are there.

Also, there is a button (CSTR) on the FCU you need to press to show constraints. Have you done that?