logged Aircraft leveling off and overspeeding with IAS/MACH mode engaged

[SteamingSpoon]

Hello,

Been enjoying flying the TriStar but it seems that every time I select IAS and MACH on the pitch mode selector during a climb, the autopilot/FD initially holds the desired speed but then pitches down, causing the the aircraft to accelerate past the speed target and overspeed if I don't intervene with V/S. Over two flights this seems to have happened consistently in both IAS and MACH hold modes. At this point it seems that V/S is the only appropriate vertical mode that can be used for a climb - I can't imagine that this is realistic at all. Has anyone else experienced this?

[Nikita2024]

I have had success climbing in VNAV to a preset altitude with TM activated when the PMS has been fully set up.

[SteamingSpoon]

Hello,

I do understand that flying the aircraft in TM/VNAV could work around the issue, I’d still want the aircraft to function properly in a speed hold mode if I want to manage the climb manually, especially when I’m flying a departure procedure that has multiple altitude and speed constraints that (to my knowledge) the PMS can’t take into account. Even then, there seems to be a bug where the TM A/T mode commands idle thrust without the AP engaged which many on this forum have already reported it seems.

[richboy2307]

Thanks, with 1.0.3 we have made changes to the AP controller, but only added this to "VNAV" for now. We are working to implement the same logic into IAS/MACH modes as well for future update.

If you have any additional feedback meanwhile, specifically to how AP behaves with TM/VNAV , please let us know.

On 4/25/2026 at 8:01 PM, SteamingSpoon said:

Even then, there seems to be a bug where the TM A/T mode commands idle thrust without the AP engaged which many on this forum have already reported it seems.

Yes, see the post attached below. We're investigating the following:

Quote

While it is correct that TM mode requires FD+AP, we'll have another look at what it should do when conditions are not met (i.e. just disengage TM instead of commanding EPR 000/IDLE thrust).