Stuck at Cruise Altitude

[misctw]

I just did my first flight (with several years' experience with the Fenix A320). I encountered two problems:

1. At an altitude restriction (15000ft) during climb, the A350 accelerated until it oversped.

2. I pushed the altitude button at the top of the descent after I had set a lower altitude. I saw the button being pushed in, and the PFD changed accordingly, but the plane did not start the descend! It remained stuck at the cruise altitude. The same thing happened when I "pulled" the button. The PFD changed to "open" descend, but the plane remained at cruise altitude.   

Does anybody have an idea?

Thank you!

Michael  

 

[Trevor66]

I'm  having the same issue, aircraft wont descend?

[richboy2307]

Hi,

Please try the following

• Check control bindings related to throttles and unassign from any devices where it should not be used
• Verify you have completed the throttle calibration process on the OIS
• Verify that your AI assistances are disabled: 

 

Also please provide screenshots of your cockpit, particularly showing your PFD, ND, FCU, MFD FMS F-PLN and PERF pages as well as your throttle quadrant for when you're experiencing such issues for additional clues as to any potential issues.

My guess at the moment is that the aircraft was not in the proper ATHR detent, as such there was overspeed or lack of descent as the aircraft is unable to command desired thrust. 

Thanks!

[whitehot43]

I'm having the same problem. Happened a couple of times now. Everything else seems to be working, but whatever I do, the aircraft will not descend. The target altitude on the PFD changes, but the FMA does not go into any descent mode.

Checked throttle calibration and this seems fine. 

Thanks

[richboy2307]

Hi,

  On 3/10/2025 at 3:27 PM, whitehot43 said:

The target altitude on the PFD changes, but the FMA does not go into any descent mode.

Expand  

Please screenshots or video clips of this as it happens will help. The plane does not descend on its own at TOD, you have to dial down the ALT on the FCU and then "PUSH" the ALT selector knob to engage DES mode.

Just for context, haven't observed this behaviour personally in the 300+ hours on A350 in testing nor seen it reported by any of our testers as yet so we need reproduction steps if this is an issue.

Like I said above, my guess at the moment is that the aircraft was not in the proper ATHR detent, as such there was overspeed or lack of descent as the aircraft is unable to command desired thrust, based on this other user report: https://forum.inibuilds.com/topic/25224-autothrottle-wont-hold-descentselected-autopilot-speed/

Thanks!