...it's this one, NO HIGHWAY IN THE SKY. To me, it seems his best, my new favourite (of his). Jimmy plays an absent-minded scientist, who mathematically predicts that a wonderful airplane will get metal fatigue after exactly 1440 hours of flight and lose its tail and crash! So then he is sent off to Montreal to investigate a crash...only to discover that he is a passenger on just that airplane, and it already has logged1422 hours!
So the drama unfolds, with the help of splendid supporting actresses Glynis Johns and Marlene Dietrich...a real cliffhanger. And then after a movie came out, it actually did happen that a kind of airplane was crashing tragically from metal fatigue!