Not leveling off at dialled in altitude in profile mode in descent

[WallyWalt]

Since SU15 I have a strange issue. On climb the aircraft levels off at the altitude selected in the MCP. In descent it doesn´t level off at the right altitude but continues to descent towards ground. It happend in three of three flights I made with the A310 since SU15, but I can´t tell if it´s a generell problem with the autopilot (i.e. also happening with V/S and level change) or just a issue with profile.

[richboy2307]

Hi @WallyWalt,

Can you share a screenshot of your PFD + FCU when you are noticing the issue? Also is this happening regardless of which procedure (STAR/Approach) or only on a specific one?

Thanks!

[WallyWalt]

On 6/12/2024 at 11:51 AM, richboy2307 said:

Hi @WallyWalt,

Can you share a screenshot of your PFD + FCU when you are noticing the issue? Also is this happening regardless of which procedure (STAR/Approach) or only on a specific one?

Thanks!

Hi, I am happy to share a screenshot once I find the time to do another flight. Hopefully this weekend. When I am remembering correctly, it was two times an RNAV/RNP Approach and the third time an ILS, but I wouldn´t bet my life on it. I´ll come back on this soon 🙂

[WallyWalt]

On 6/12/2024 at 11:51 AM, richboy2307 said:

Hi @WallyWalt,

Can you share a screenshot of your PFD + FCU when you are noticing the issue? Also is this happening regardless of which procedure (STAR/Approach) or only on a specific one?

Thanks!

Hi @richboy2307,

I could narrow it down: The issue occurs when decending in Profile mode and then manually selecting a speed. The MCP than switches to level change but apparently doesn´t arm the before selected altitude. It doesn´t happen when selecting a altitude and descending down to it with either lvl chg or profile from the beginning.

If I am not mistaken, before SU15 it was possible to manually select a speed and still decent in profile mode? But either way the plane shouldn´t descent below the selected altitude. As the screenshot shows, I have slected 7000 feet but the plane kept descending below 7000 ft (at 6700 ft with 1800 ft/m descent rate). The flight mode annunciator shows SPD and NAV but not the ALT in blue, which it does when descending with level change from the beginning.

Hope this helps figuring out the issue.

[richboy2307]

On 6/16/2024 at 8:44 PM, WallyWalt said:

The flight mode annunciator shows SPD and NAV but not the ALT in blue, which it does when descending with level change from the beginning.

Thanks for the write-up. I've shared with the team for further investigation.

 

[F4b3l]

I found this old thread after I experienced the same problem today.

I was descending in vertical speed mode. As i approached Fl250 i got the ALT* in my PFD. Instead of changing into Altitude Hold mode, it changed into level change (level change button on fcu turned green) and descended through the selected Fl250 without signs of leveling off and returning.

I really dont know what happend and I wasnt even able to replicate it. I tried everything to do it again, but it was impossible to even select level change manually when Alt* appeared on the PFD.

I guess this is something that will ocure rarely but nevertheless i wanted to let you know.