One generally needs a 4 year degree somewhere in the process, there are a few stories without one, a few.
The military is usually a great option, for college $$ & better yet flight training, if one is capable and so inclined. There is much more to it that just strapping in a plane and training. It's not cut out for everyone.
At his age he can dip his toe in a few areas. There is a local CAP unit, just to get some feel. He could take a private pilot ground school, minimal expense.
If $$$ is available he could steer towards one of the aviation flight schools, Emery Riddle, UND, Purdue, and a host of slightly lesser knowns.
Where you live can have a bearing on recommendations. It's not the kind of career one can just sit back & let it happen, initiative is needed.