[eyedigress]

and be sure to know ground level horizon as a starting point.

[Tolsti2]

There’s just too many other pictures of contrails that extend to the ground though. It wasn’t at the ground, it was 35000 feet where we see the ‘horizon’ and the contrail intersect.

[TXnMA]

Since I happened to have Canvas X running while I am creating a map, I did a quick sketch to illustrate the apparent size and angular velocity distortion due to perspective.

NOTE THAT BOTH APPARENT OBJECT SIZE AND APPARENT ANGULAR VELOCITY DECREASE DRAMATICALLY WITH DISTANCE -- even though the A/C is at constant altitude and angular velocity.

Note also that the eyepoint in the video was not the surface, but some varying, unknown height ("h") of the helicopter above ground. AND that the lens was zoomed -- thereby further distorting apparent size and velocity.

The arc circumference of the earth is, of course 2 * Pi *R, and the cicumference of the flight path is 2 * Pi * (R+A).

The sketch is not to scale, but I leave the arithmetic as an exercise for the reader. I have already wasted more time trying to squelch this idiocy than is warranted.

If you read that as, "You dummies are not worth any more of my time and effort", so be it...