"The instructor of a class for people who are afraid of flying learns to relax." Does this sentence mean that the instructor learns the people (who are afraid...) to relax ? Or does this sentence mean that the instructor himself learns to relax, and should one add the word "how" if one wants to state that the instructor learns the people "how" to relax ?
It's the instructor who learns to relax. He teaches people (how) to relax.