1. Using bond1's animated texture shader, apply a [looping] 'animation' of clouds slowly passing from the end of one large rectangular plane (wider than the aircraft) on either side of the aircraft, to the other end of the plane.
1b. Using bond1's animated texture shader, apply a similar animation to a few various windows on board the aircraft to break up the repetitiveness of the anim cycle on the larger planes outside of the aircraft. Might also help break up the repetitiveness if you pulled some of the shades/visors down on some of the windows.
2. Make a large cylindrical plane that surrounds the aircraft with plenty of room on either side of the airplane to make the curvature of the cylinder less obvious. Use a rectangular texture (4096x512 for example), or a sublte tiled/repeating one, with clouds of the same appearance as your skybox. Animate the cylinder to rotate 360 degrees on a continuous cycle.
2a. Use multiple cylinders, one inside the other, with varying cloud positions and transparency values to get the perfect amount of 'traffic' you want the player to see in the skies when he looks out the window.
EDIT FOR #2: Just realized a rotating cylinder would make the clouds run in the opposite direction on one side of the plane. -.-
SIDENOTES:
-Use a [still] skybox with the look you see fit for your level, and then use similar cloud styles for the textures in the above methods so everything will blend together smoothly.
-A subtle white fog may help blend all of the running animations together in the distance, of course if the fog setting is too heavy, you'll see it on the plane.
-Using bond1's animated texture shader, you can place a thin rectangular plane in the far background, behind some of the transparent animated running clouds, and 'animate' a bird or two flying past the plane behind the cloude.
Sorry everything's a bit unorganized. Hopefully you can whip something up, or come up with a better solution with what's up there.
Kravenwolf
