In English it's Colonel.

In Japanese, it is captain, but when translated to English, the Japanese term becomes "Lieutenant Colonel." Besides, he's now a colonel...

In the American version it's Lientant Colonol but in the Japanese version it's Captain. But in the Japenese Version, he's a Captain till the end. He doesn't get promoted or anything like that. I'm going by the Japanese version, not the American one so

techniacally it's lutenant cornal mustang...