Formula to calculate different coordinates for flight routes in KML

Question

I need to create flight routes in Google Earth. Example from point A to point B, How do i get the equivalent middle point for both and along point A to B, there are also many different coordinates joining so that the line would be a curve.

Answer 1

Generally you should use the great-circle distance to compute the distance of two point on the surface of a sphere, like in this case the Earth. Even WolframAlpha uses this to compute direct travel times.

This would also define the midpoint for you uniquely.