^ I'll go in order:
1) Its ok, nothing special, but its kinda hard to take pic out of an airplane window and not make it look like an am photo. Try visiting
http://www.airliners.net/ for good airplane photography.
2) Its also nothing really special, but I can't come up with anything else to do with it so I'll keep off this one
3) This one I like a lot. It takes your eyes into the picture as it follows the lines and I get a nice sense of how long this thing is, and the overall atmosphere of the airport. That being said, I think it might be a little better without the guy on the left, but it could go either way. Overall, I think this is my favorite photo out of the set.
4) I like it, but crop out the black tree (?) or telephone pole on the right. Its distracting. Other than that, I like the colours, and the sun's reflections leading your eye straight into the middle could be neat.
5) ?? What's the objective of the photo here? Again, there's not much to it, and overall I don't think you can do much to this photo. Kinda too typical and boring.
Keep taking more pics, especially ones like 3. good luck