gravity32,
What puzzles me is what evidence will the calibration chart reveal.
I ask this question because the accuracy of the pressure altimeter is subject to so many variables. The only evidence I can see is evidence that the barometric measurement of altitude subject to an abundance of errors.
The only time that the inherent error is insignificant is when the instrument is at high altitude and every other altimeter at that altitude has a standard reference datum.
Here is a link to a document which illustrates the errors measured by a barometric altimeter. Although the study uses mountain climbing and altimeters to illustrate the problems, it applies equally well to any pressure altimeter.
The use of altimeters in height measurement