Step Climb / Auto Step Climb Logic in A350 Questions

[Remy Mermelstein]

I just got the A350 last week and have had several very enjoyable flights in it. Some questions though about the step climb logic with auto step climb:

A couple of my flights the Auto Step Climb worked perfectly with the imported Simbrief Step Points; however some other flights where the plane also just decides to not step when it gets to the point and deletes it. 

For eg, right now I am flying NZAA-KJFK. My simbrief FP had an initial CRZ of FL350, but I decided to start at FL330 given performance. So, the steps:

CLB to CRZ FL330

[My own added OPT Step to FL350] FMS decided in 300nm from CRZ.

Then continued with the planned Simbrief Steps:

1. STEP @ 36S152W FL370
2. STEP DOWN @ 27S146W TO FL360
3. STEP @20S144W FL370
4. STEP @07W40 TO FL380
5. STEP @01S139W FL390
6. STEP @BIGBY FL410

The plane correctly climbed to FL350 in 300nm from CRZ.

The plane then did NOT descend to FL360, it deleted this step

The plane stayed in FL350 past the planned steps to FL370 and FL380 and FL390, the FMS deleted these steps from the STEP ALTS page.

The FMS deleted my BIGBY FL410 Step and instead had "OPT 390" in place, with the OPT CRZ showing FL395, the OPT point for CLB to 390 kept going 2nm, 1nm, 0nm, and AUTO STEP would appear as a msg, but the plane will not climb unless I manually tell it to climb.

I tried adding new step points to FL390, FL410, and INSERTED them into the active FP, but the FMS kept then deleting or changing them to OPT and not climbing.

So mixed bag here, and I would love some answers. I have AUTO STEP climb and Import from Simbrief turned on in the OIS. 

Question - can the plane handle descent steps and then climbing back up? Is there a way to tell Simbrief not to do descent steps?

Should the Cruise alt i put in the MCP be the initial, or the final? I assume initial.

Running MSFS2020, just bought the A350 last week, running latest version. 

Thanks in advance,

Remy M.