I don't know to explain this feeling but for some reason, every time I take a flight (generally, between the West and East Coast of the US), I have this weird feeling in my gut as if the world ended.
I guess, in a less morbid way, it feels like every time I step onto the plane, a "chapter" of my life is dramatically ending, being wiped away, and I'm being tossed into something completely new. This makes sense for a few flights I've taken in my life, like going off to college, but not most of them.
Sometimes, it takes me weeks to re-adjust back to my daily routine after I land. My head feels all scattered because it feels like everything that ever mattered ended, and I really have to push myself to "get back to work" and back to my routine.