A brilliant movie that has stood the test of time with great actions sequences and a stellar cast of actors. There's no CGI as it didn't exist in those days (1968) so all the flying sequences are mostly real except for the Stukas, planes blowing up on airfields or crashing which are all radio controlled models and full size models. Some of the scenes with planes taxiing were planes that could only move on the ground but couldn't fly.
Footage from this movie has been used time and again in documentaries about the Battle of Britain because the footage is just so good.
Highly recommended viewing.