Another worst travel fear - bad weather. I had a flight home from FL once, and I swear I thought we were going down. My son was strapped tightly into his seat - we hit an air pocket and his butt was literally six inches off the seat! For about 20 minutes, all you heard was screaming, crying, and praying.
To this day, if there's any kind of inclement weather when I'm flying, I get concerned.