=>Easy Completion: On level 2, hold U so that you always face the water, and
you won't have to fight as many planes, but just the boats and subs. You
still have to kill some of the planes, but not as many. If you also move L
and R repeatedly, you won't have many ships to fight, either.
=>Even EASIER Completion: While playing, hold U+R and you will easily fly
past most obstacles. You still have to land, though.