Graphics adapters based on GPUs from ATI have never been very successful in flight simulators from Maddox games. And the primary reason for that was the inefficient OpenGL driver, because these games use this particular API by default. This API provides the best image quality for them.
Well, the new RADEON based graphics cards failed to work wonders here. RADEON X1800 XT and RADEON X1800 XL performed equally fast in low resolutions, which points at a definite issue with the OpenGL driver. However, in high resolutions RADEON X1800 didn’t show anything remarkable. Only in 1600x1200 with enabled anti-aliasing, the top ATI RADEON model manages to perform at least close to GeForce 6800 Ultra. Here I would like to point out that despite their evident defeat, ATI RADEON X1800 XT/XL based graphics cards provide acceptable gaming performance in all resolutions except only 1600x1200 with enabled FSAA and anisotropic filtering.