Wow, that takes me back!  I read that when I was a kid in highschool.  The book belonged to my dad (wonder if he still has it?).  I didn't know someone had turned it into a film.  It inspired me to write a similar story for the book, "Echoes: An Anthology of Warbirds Fiction" (published back when I was flying Warbirds, and before AH).  It tells the story of a German pilot during the battle for France, in the form of diary entries written to the pilot's son.  I posted the fictional diary entries during a multi-day scenario of the Battle of France, one entry each day.  They were actually accounts of my own missions during the scenario, but I posted them without any explanation.  The best compliment I ever got was when someone posted a comment in the thread, which read, "Wow, it's really amazing to read an actual account of the battle.  What ever happened to this pilot?"