The Flying Soldiers are enemies that appear in scene 3-1 that appear as a miniboss.
The flying soldiers are very much alike to the regular Soldiers you see throughout the entire game except they now have a propeller for them to fly.
The flying soldiers first appear as you get to the middle of scene 3-1. They fly over you and try to land bombs on you by going left and right. All you have to do is try to hit above them when your in alignment with them. In total you have to face against three of them.
In the Japanese version, it's much easier to defeat them because you can use the Headcase that's near by. The Headcase was removed in the International version, making this miniboss much more harder to defeat.