A trifle tricky sometimes then if you're using QFE?
Simplicity itself from Australia the land that gave you CS Hames and what are probably still the finest one volume technical manuals to the PPL and the CPL.
This is from Balloon at Brisbane.
https://www.brisbanehotairballooning...ty-height.html
No more on altimeters though. It's far too much of a wind up and probably totally irrelevant, or at the least ignored, in swamp flying.