ATS drops out, unable to re-engage

[MrNelz]

Since the 1.61 update at random points in the flight the ATS drops out and cannot be re-engaged. What's changed with the ATS logic? This did not happen with the previous release.

Also, if there is an ATS disconnect in-flight, how do I re-engage the ATS? Pressing the TOGA button in-flight comes with a heap of problems (including automatically starting the go-around checklist)!

Edited June 26, 2022 by MrNelz
Additional Info

[MrNelz]

Think I've found something. In the descent as the P2 gets to APU/PACKS transition he selects the "BLEEDS OFF" selection on the ENG Perf page, this only leaves TO as the available thrust setting and disconnects the ATS. If I reselect 10TH on the bleed and re-select CLB thrust setting I can re-engage the ATS in SPEED mode. This is very different to how it worked in the previous release and maybe a bug.

Edited June 26, 2022 by MrNelz

[Ev1dentSnow]

I also had this problem on my last flight and I have absolutely no idea what the cause was

[marcvc]

I had it too, right after packs transition during descend.

No way to turn it back on.

 

Incidently, during the flight before, after take-off, I couldn't change power limit to CLB, it was stuck at TO.

Only after packs transition this was possible, but then a few mins later ATS quit as well.

I wonder if something has changed in the interplay between bleeds and ATS...

 

Only two flights so far and I ended up with a broken ATS each time.

Edited June 26, 2022 by marcvc

[Pils]

3 hours ago, MrNelz said:

Think I've found something. In the descent as the P2 gets to APU/PACKS transition he selects the "BLEEDS OFF" selection on the ENG Perf page, this only leaves TO as the available thrust setting and disconnects the ATS. If I reselect 10TH on the bleed and re-select CLB thrust setting I can re-engage the ATS in SPEED mode. This is very different to how it worked in the previous release and maybe a bug.

This is (now) the correct behaviour. From the V1.6 change log:

2884: Don't compute CLB, CRZ and MCT N1 targets when engine bleeds are off
 

You need to follow the checklist and select a thrust rating that isn’t one of the above when it says “N1 TGT”, before the “APU / PACKS TRANSITION” is completed by the Virtual F/O.

Edited June 26, 2022 by Pils

[Pils]

On 6/26/2022 at 9:22 AM, marcvc said:

No way to turn it back on.

Turning it back on (not arming on the ground!) in flight, assuming the ATS mode display is blank, is a case of selecting a valid thrust limit and pressing the ATS button.

Edited June 27, 2022 by Pils

[marcvc]

4 hours ago, Pils said:

Turning it back on in a case of selecting a valid thrust limit and pressing the ATS button.

Thanks - problem solved now.
I run a manual (paper) checklist and was doing the "packs transition" one step out of order and therefore could not set a thrust limit (other than TO).