Hi,
Having been flying the B757 since Dec 2018, I have recently noticed some serious errors with the FMC/VNAV performance that makes the a/c if not unflyable then not enjoyable. Can the developers please look at the following:

I loaded a flight from EGNS to EGLL. Dep RW26 arrive 27R. FP route TIMIS Q39 NOMSU UQ4 WAL UY53 NUGRA NUGR1H. Cruise level FL290. Complete FMC with say TO1 Flaps 5. Remove any discontinuities.

Now look at the legs in the FMC. Straight away you will see the cruise level is only FL200 when we have set FL290 for the cruise in VNAV. The reason for FL200 is there is a height restriction of FL200 at Topid. (See Navigraph charts). So this restriction overrides the input data. Tobid is a significant distance away, the cruise level of FL290 is easily achieved. 

On VNAV climb page you will see the height restriction of FL200 at Tobid top right. Delete this restriction and you will notice the FMC legs now show a climb to FL290. Let say we then take off and begin the climb to FL290. To keep ahead of the a/c, you select FL200 at Topid. The FMC again changes the cruise to FL200!!
At Tobid the speed for VNAV is shown 296. ATC clear you direct to BNN from Tobid. The FMC now makes VNAV reduce your speed to 220 from Tobid. The 220kts restriction is at BNN. So you will then fly according to the VNAV at 220kts for 205 nm to BNN!! The only way to overcome is to manually control speed and descent.
This has never been an issue. I have used the repair option to no avail. As this is a very new issue for me I cannot suspect the recent P3D V5.3 HF2 if not before.
No such issues with he Classic B737 or B767.

There are some other very odd things happening. Anyone else finding this?

Regards,

Keith

Sorry meant to say I can only suspect P3D etc. Forgotten how to edit.

Keith