Don’t forget the effects of gravitational pull from nearby large bodies.............
I knew a guy that was hired by the military in an attempt to figure out why the big ballistic missiles weren’t tracking properly. They do take into account the variable geology and topography and the resultant change in gravity. They thought it might be due to an “anti-gravity” force and he attempted to measure that in various experiments. He said the results didn’t prove anything for or against anti-gravity. I thought it was interesting that the military was interested in it, and he, being a gravity expert, didn’t dismiss the idea out of hand.
As Dolly Parton always says, the right mass distribution can exert a significant attractive force: