United Flight 23 to Chicago: The First Airline Terrorism?
In October 1933, a plane bound to Chicago from Newark via Cleveland exploded in the skies over Chesterton, Indiana. It's cited as the first incidence of American airline terrorism... but it's still a mystery.
80 Years Later, Plane Bombing Remains A Mystery
In October of 1933, a United Airlines flight with seven people aboard was blown up with a bomb over Chesterton, Indiana. A young Federal Agent named Melvin Purvis headed up an exhaustive investigation, involving hundreds of leads. But eighty years later, the crash remains a mystery, the first...
Informative link on commercial aviation bombing history.