Look, I'll be honest. Your shots not being good has absolutely nothing whatsoever to do with the fact you were using a 70-300, they weren't good because you don't yet know how tho handle the camera. I've said it before and I'll say it again, quit worrying about equipment and go take photos. 70-300, 70-200, IS, non-IS, 50-500, 100-400, it doesn't make the slightest bit of difference in the grand scheme of things. Forget what you have stuck to the lens mount on your camera; whatever it is it will take photos, so go use it! You're NOT going to improve your photography skills by talking about equipment, you ARE going to improve them by going out and taking photos regardless of the equipment you're using.
That one isn't IS, no. Canon make 4 versions of the 70-200; the f/4 IS and non-IS and the f/2.8 IS and non-IS. Th f/4 non-IS is perfectly good for aviation use. You don't really 'need' IS (although it may be handy occasionally) and you certainly don't need f/2.8 for aviation.