A classificação de Miles O'Brien não foi consistente durante sua aparição nos shows.
De Wikipedia :
During the story progression of TNG and DS9, O'Brien wears black silver-rimmed insignia, or lieutenant junior grade (TNG: "Encounter at Farpoint"), lieutenant insignia ("Redemption, Part II", "Data's Day", etc.), and then black gold-rimmed insignia (DS9: "Emissary"). Sergey Rozhenko calls him a Chief Petty Officer in "Family" (TNG) but he had been referred to in previous episodes as Lieutenant. Eventually, O'Brien receives a distinct senior chief petty officer's insignia and his rank is emphatically identified in "Hippocratic Oath" (DS9).
Em Memória Alfa :
The character of Miles O'Brien, and the exact rank he held in Star Trek, has a history of its own spanning the length of the character's existence.
In thirteen years of the character's appearances, only in the last four was his rank established to be presumably senior chief petty officer (although this term was never directly used on screen). Through various other stages of the character's development, O'Brien was referred to as a crewman, a lieutenant, and various script notes indicated he was a "warrant officer." The novelization of "Emissary" indicated O'Brien held a rank known as "ensign junior grade".
O site, em seguida, fornece um relato detalhado das fileiras que ele realizou nos episódios que ele apareceu; devido ao seu comprimento, eu não o relatei aqui, e encorajo-o a simplesmente ler na fonte.