Stress
Imagine going to work every day, knowing that a single mistake could bring down a plane full of people. That's like a McDonald's manager causing the death of hundreds by failing to notice that his burger flipper forgot to add a pickle slice to the last Big Mac.
To make matters worse, your restaurant is making 350 of them a day, meaning you have 350 chances to mess it up before closing time. And corporate just called—now the pickles need to have thirteen ridges on them instead of twelve. Good luck.
Needless to say, working as an aviation safety inspector is an incredibly stressful job. It requires you to be paying attention and focused every single day, regardless of how much sleep you got last night, the fight you got into with your neighbor that morning, or how sleepy that McDonald's Big Mac you ate for lunch just made you.
Tack that onto what's often an incredibly busy schedule with intense oversight and, no, you're not exactly reaching the same plane of Zen as, say, a crossword puzzle writer.