The path in the post has nothing to do with the great circle. The shortest path is very similar to how it appears on the Mercator projection (actually slightly bent in the other direction) because SF and Houston are fairly close and in a position where Mercator distortions are less pronounced.
Also, a line is the shortest path when the 2 points are both on the Equator (where the projection distortion is zero)
Worth pointing out too, that the air isn’t “flat” either, you can have headwinds, tailwinds, and turbulence that will affect the shortest and most economical path.
The path in the post has nothing to do with the great circle. The shortest path is very similar to how it appears on the Mercator projection (actually slightly bent in the other direction) because SF and Houston are fairly close and in a position where Mercator distortions are less pronounced.
Also, a line is the shortest path when the 2 points are both on the Equator (where the projection distortion is zero)
Worth pointing out too, that the air isn’t “flat” either, you can have headwinds, tailwinds, and turbulence that will affect the shortest and most economical path.
It’s also good to mention that the projection shown in the tweet wasn’t Mercator either, it was a globe rendered via Apple Maps.