Thanks, I only find the background distracting on the 4th one where the top of the canopy blends in with the snow. Otherwise there is decent isolation especially number 2 against the cloudy sky..
Great shots. Photographing airplanes is hard, as you rarely get to see them close while in their element. Maybe an even narrower angle would really draw the eye to the plane instead of around the contrasty snow and bare earth (but I can see that would be incredibly difficult at best).