FLCH nose dive

[Aaron737]

First, there are many elements I enjoy about this plane. It's very immersive and fun to hand fly. Great work!
I understand VNAV has its quirks though I am usually happy to manage my own descents when VNAV has problems.
However, when I use FLCH from cruise it doesn't gradually ease into the descent. Rather, it agressivly points the nose about 10 degrees down and then slowly rises to find the speed. Meanwhile the mach has increased significantly and I have quite a few sick virtual passengers in the back. 
Is this a known bug? Couldn't seem to find it on the list.

Thanks,

Aaron

[Litjan]

Hi Aaron,

I have not been able to reproduce this behaviour - it is perfectly normal for the aircraft to dive quite steeply in FL CHG when goverened by Mach speed in the descent, the real plane does it, too - thats why many like to enter the descent more gradually with V/S.

The reason is that to fly constant Mach you need to fly with increasing IAS when descending, so the plane needs to accelerate while going down - often leading to descent rates in excess of 5000 feet per minute.

You will notice though that the plane is trying to fly a constant Mach (as indicated on the MCP) and you as the pilot have every right and authority to dial that one down a notch or two to avoid the dive becoming excessive.

Also note that passengers have no ability to feel vertical speeds - they can only feel vertical acceleration. A steady 20.000 feet/minute would feel totally fine to passengers.

Even body pitch angle is something they can not determine without looking out of the side windows - the feeling of "pitch" is goverened by longitudinal acceleration - accelerating feels like "pitching up" so that the nose-down attitude combined with the acceleration of the plane trying to fly constant Mach somewhat cancels out.

Cheers, Jan