I remember doing a patrol off of Malta before, and coming upon a large cargo. As I'm lining up my shot on her, I hear plane engines. Of course I cheated a bit and used the external camera to sneak a peek at them. I don't recognize the insignia so I crash dive. Turns out they were a couple italian planes on patrol! It was fun to watch them attack.
I did tell my watch officer to shoot the bastards down if they sunk the ship and stole my tonnage!