The game's graphics were done at length and detail. The designers didn't stop at standard surrounding such as mountains, different obstacles, smoke and such. Au contraire, they went one step further and integrated smooth ground texture, clouds you can fly through and objects that suddenly appear. Since Crimson Skies isn't another airplane game, but a game anyone would want, the Microsoft and Zipper designers and programmers spent many hours developing new texturing techniques, so no matter the altitude of the plane the textures look magic and perfect. To fill the terrain, texture quota was reduced and mutually rotated, so the image quality is high.
Many missions require very low flight altitude.
That means the graphic design quality of the ground has to be high. At low altitudes, the impression of speed is higher, and that was taken into consideration. When on a long flight, you'll realize that the distances in Crimson Skies are lot shorter than it would have been expected. The planes can perform air acrobatics that are in compliance with laws of physics. If you get the hang of these acrobatics, dogfights will be smooth like silk.