"Above and Beyond" with Lloyd Nolan and William Holden. They got access to Edwards AFB during the Golden Age of X planes for goodness sakes! The story is a thinly disguised version of (a famous test pilot)'s exploits if memory serves. Note: I had originally typed the actual name of this famous pilot, who broke the sound barrier, and when it posted to the board the name had been removed automatically. I happen to know the story behind this, but that automatic change is hilariously inappropriate in the context of this post's mention of a 1950's film)
Speaking of William Holden, how could you guys have forgotten to mention "The Bridges at Toko-Ri"??
My hat's off to the person who was thoughtful enough to mention "633 Squadron"...bravo!
Although not an aviation movie specifically, one classic should be mentioned if for only one memorable scene: "It's a Mad Mad Mad Mad World". The gentleman who flew the Twin Beech through the sign was later my first flight instructor, so I have a personal connection to that movie. (well, two personal connections, but that's another story).