That's just word salad.It's a simple drop per mile over a horizontal line to the vertical back to the ball/globe, so where does this parabola come into it, and how does that supposedly work on this ball?
I know you're simply parroting an incorrectly applied formula without a scintilla of mathematical understanding,* because it's only ever found being similarly misapplied on every single gormless flat earth site.
You parrot it because you're either mathematically illiterate or disingenuous or possibly both.
I can let you have the correct formula if you wish.
And how are you getting on researching those pesky flight plans?
*for transparency I must point out that I've had help here from a proper and extremely well qualified mathematician.