Casual Observer pretty much makes the argument, but I'll make my own version:

As you know, LBFM stands for "Little Brown ****ing Machine."

"Hooker" isn't racist. "Lady of the night" isn't racist. "Little Brown ****ing Machine" is racist because it (a) specifies two racial characteristics [stature and skin color] and (b) pairs them with a dehumanizing term [****ing machine].

Ask yourself, would you have been equally comfortable with someone writing that captains just wanted to get to Atlanta so they could see little black Sambo?

I'm sure those who use the term mean nothing by it. They probably picked it up before they became critical thinkers, and they've probably never been challenged on it before. But they wouldn't be pilots if they weren't smart. Upon further reflection, they'll come around.