This is great!
The first time I played I had no idea what I was supposed to do - I didn't pay attention to the news reel at the start and had no idea what Q-E to switch actually meant.
The first target I fired on was the nearby A-A unit.
However, I tried another go today for the review and figured it out. I shot down all the planes and won the battle.
It would benefit from a map overlay showing the incoming planes and the A-A positions.
Nice job!