V/S Values
When looking at the V/S values derived from the FR24 data we will need to take into account that this data is not recorded in a way that allows to have accurate data to derive a precise sink rate from the recorded Mode-S data.
Neither the time stamps / intervals nor the resolution is up to that task. Therefore you can see a fluctuation on the V/S data that might not be there.
The track on the other hand clearly shows that the plane was on A/P.