Odds of Getting In
Up to 70% of applicants will not become certified. Generally, applicants don't succeed because they don't have the intense focus that it takes to perform the job. That's one of the things that an interviewer is going to be watching for, so don't get distracted and start zoning out looking at the nameplate on his desk (even though he does have the funniest name you've ever seen).
If you can't look him in the eyes for half an hour, he's going to assume that the planes under your watch might receive a similar amount of attention.