That's not an ideal use of an animated GIF. 600+ kb is too large to be useful on a web page.
You might separate the jets from the background. Set the clouds and text as a JPG image in the background. Animate the jets in a GIF file to overlay the JPG file.
Seeing that this is simply a motion from right to left, you could probably also do this with a transparent GIF or PNG file, moved with DHTML.
Marian & Mylenium,
Thanks for the information. I tried to just animate the aircraft and while the artifact issue was solved, the animation simply wasn't smooth enough for my liking. I agree the SWF option is the way to go but due to IT restrictions, that software isn't readily available to the end users. I use Preimere Pro too so creating the files would be a breeze but pointless to do so if the file won't launch. I appreciate you both taking the time to not only answer the question but to explain why going the route I was going wasn't the best option. Cheers!