In my first post, I made a little oversight there. I mistakenly referred to the return value of the field <Parameter(part.ParameterTypes.Z_AltitudeMSL> as "Pressure Altitude."
As a matter of fact, the quantity of geometric altitude (Z) is given to facilitate the computation of, for example, distance between or height of objects.
So, the value (Z)=5000m needs to be translated into the corresponding geopotential altitude (H)=4996m.
The good news: this doesn't significantly alter the result of my calculation example...
