Let's do the math:
According to spherical trigonometry, rate of curvature on a ball, using accepted earth radius of 3, 959 miles gives angle of downward curvature of 3.2 inches x miles squared, where miles is distance between two points, A and B.
Distance from Vandenberg to Phoenix equals 400 nautical miles.
400 x 400 x 3.2 = 512,000 inches
Divided by 12 = 42,660 feet
Therfore, the launch should not be visible at all from Phoenix because the curve of the earth would have dropped away by 42, 000 feet beloe the horizon in Phoenix.
You cannot see around the ball.
Yet there is the rocket in the sky, proving with your senses, your eyes, and math, that the earth is flat.