From the viewpoint of pure special effects..before the era of computer generated stuff..my vote is for "Battle of Britain"..amazing aerial photography..using real vintage WWII planes...at the time the movie was being made, the studio as said to possess the 3rd largest air force on the planet.
My personal favorite is one that rarely turns up on the tube.."The Cruel Sea", based on Nicholas Monserrat's novel..about the crew of a Royal Navy corvette, and battles against U-boats. One of the rare instances where the film was very faithful to the novel, and almost as good.
Both excellent choices.
The ME-109s used in the movie had been surplused out by the Spanish Air Force.
Ironically, one of the mods made over the years was to replace the original engine with Rolls-Royce Merlin engines, which were also originally used in the Spitfire.