This is mainly a question for the globeheads because I don't really see any interest in this from flat-earthers.

My question is this: Where are the experiments that prove that g decreases with altitude? I searched for them and all I see are people doing equations on white boards and notebooks and some stories about a tuning fork inside a Concorde or some crap (excuse the French).
I understand fully that I can do an equation that will predict that g at the top of Mount Everest is supposedly 9.77 m/s/s, but where is the experiment that shows this? I have no bias against the claim that g decreases with altitude, but I need to see the experiments... Equations alone aren't good enough... Show me the experiments. Even if g decreases with altitude (which I'm inclined to believe myself), how do you know that reality matches the prediction? Can't wait to see your replies.