15. “If the Earth were truly a sphere 25,000 miles in circumference, airplane pilots would have to constantly correct their altitudes downwards so as to not fly straight off into “outer space;” a pilot wishing to simply maintain their altitude at a typical cruising speed of 500 mph, would have to constantly dip their nose downwards and descend 2,777 feet (over half a mile) every minute! Otherwise, without compensation, in one hour’s time the pilot would find themselves 31.5 miles higher than expected.”

Ok, another one related to the error in points 7 and 12 – not understanding what flat or level means in relation to the gravity of a sphere.

“Level flight” is flight that keeps the plane at the same height relative to the mass of the earth. A plane won’t fly in a geometrically straight line, rising higher and higher in relation to the earth’s surface.

If it did, it would be rising higher in the atmosphere, and this would involve using energy (fuel) to rise higher, which means to overcome gravity. But a level flight line in relation to the earth is a circle, not a straight line. 

Frankly, an author who can put forward such an obviously fallacious argument all claim to credibility.