If you compare the film to the original book they are quite different in many respects. In the book the ruthless ambition of the central character, Bruno Stachel (a pilot in the German Army Air Service) enables him to survive the war while 'better' men are destroyed and, it is implied, that Stachel finds his thoughts and talents perfectly in tune with those of a nascent Nazi leader. The Stachel of the film is killed in the final scene - his ambition destroys him in the end and it is the good men who survive. Perhaps in the 1960s the film world could not quite accept an ending which implied that evil might well triumph after all. George Peppard's Stachel is not quite as successful nor as hard as his model in the written work but Peppard does portray, quite well, this young man's use of the officer corps of the German Army Air Service and his (dishonestly secured) fame as a fighter pilot as a means of escaping from lower middle class mediocrity.
That said this is one of those 'good' flying pictures. OK, we know that some of the aircraft used were Tiger Moths and Stampes painted accordingly though to be fair the film also arranged for replica Fokker DrIs (the famous 'Triplane'), Pfalz DIIIs and Fokker DVIIs to be built especially and they add some solid authenticity (on the other hand, the a/c are camouflaged in schemes that they never wore in service for greater dramatic effect). Nevertheless there are moments in the flying sequences when the camera (and Peppard to be fair) does capture those occassions when (to those of us who love flying) flight can be pure joy.
The very beginning of the picture when Stachel, as an infantryman of the German Army in the trenches of 1916 looks up to see two aircraft dogfighting (and is entranced by the 'silver' spectacle which contrasts with the mud and ooze of his existence), over which Jerry Goldsmith's terrific theme music is slowly introduced, is certainly one of my favourite film moments.