I was an air traffic controller for 35 years. I very highly recommend that as a career path for anyone who has the aptitude.
It’s a bit hard to tell whether a person has the aptitude or not without giving it try. But if a person is intelligent and quick-thinking, that’s a very good start. By quick thinking, I don’t mean witty or even good on his feet (in conversation). I mean just being a fast thinker. Flexibility (the willingness to change the plan) is also very important.
With a BS degree he is qualified to apply. No specific training or education is required to apply. Although if he does get the job, I’d recommend learning as much as he can about flying and aviation in general (most applicants don’t do that, but they should). Open bids come out every so often. The last one was about 2 or 3 years ago, I think, so the next one might be soon. They have in the past gone a decade between open bids, so if he’s interested, be sure to jump on the first bid that comes out.
There is a period of training in Oklahoma City, then on-the-job training at an actual facility. If he doesn’t have the aptitude, he will probably fail one of those two training programs. (I say probably because some with very weak aptitude do make it through, unfortunately. If you don’t have the aptitude and you do make it through, you might not enjoy the job all that much.) If he fails then he’ll have to fall back on his degree.
The pay is very good (more than most college graduates), and the job security and pension are fantastic. You work with sharp, fun, and very interesting people. There is never work to take home. When your shift is over, you’re done. The work itself is very rewarding and, for me (and for the majority of controllers who are good at their job), extremely fun. I really, really loved it. If I had to do it over again, and my options didn’t include things like baseball player or internet billionaire, I’d pick the same career.