Real U-Boats also had a problem with aircraft so it is suppose to be that way.
You have no Leonidas orders so dive before the plane gets anywhere near you.
Your job is to stem the flow of supplies to the evil and most fowl English and later Amerikaneren Schwein! (To be said with the accent of a German in an old 1930's anti-Nazi movie)
Hurry up with your training and make the Irish happy by killing the English.
Wulfmann