I've wondered why he was called "chief" O'Brien even in TNG. What was he chief of, since Geordi Laforge was engineering chief?
On the Enterprise, he was the Transporter Chief.
Oh, thanks, I didn't realize that.
I had just been having this discussion with my 12 year old, and I explained to her that O'Brien was Chief Engineer on DS9. Then we were watching a TNG episode where someone called him "chief" and I was confused.
See, now that I know, I don't have to be embarrassed in front of my kids anymore.
I feel so nerdy.