Chief petty officer Chief petty officer ( CPO ) was a non - commissioned officer rank used by the service organizations in various culture s , including Starfleet . The origins of the rank chief petty officer can be traced to Earth , where the title was used by the United States Navy . ( ) In Starfleet , chiefs were subordinate to all commissioned officer s , they had far more experience and practical knowledge than ensign s and lieutenant s , and were expected to act as mentors to them and to the junior enlisted assigned . ( ) As such , chiefs were often among the actual leaders in a Starfleet organization , and could even hold the authoritative position of Chief of Operations . Chiefs served with distinction in most Starfleet branches and specialties , but were particularly visible in engineering and other technical trades . ( ) During the late 23rd century Starfleet chief petty officers where also defined as senior chief petty officer and master chief petty officer . ( – ) When Sergey Rozhenko spied Miles O ' Brien as the transporter chief aboard the in 2367 , Rozhenko was excited to meet another chief petty officer . When O ' Brien introduced himself , he acknowledged Rozhenko as " sir " , to which Rozhenko told him not to call him sir , because he used to work for a living . Sergey ' s wife , Helena , then told O ' Brien that he was just joking and that Sergey ' s proudest moment was when their son , Worf , had earned his commission . Sergey then added , " " Imagine . An old enlisted man like me raising a boy to be an officer ! " " ( ) Several years later , O ' Brien was identified by a Jem ' Hadar as the rank of " chief petty officer , " or " " what Starfleet refers to as a " noncom , " " " adding " " you must have a great deal of experience [ . . . ] that makes you a priority target . " " ( ) In 2374 , Cadet Dorian Collins of the introduced herself to Nog and Jake Sisko as " acting chief petty officer . " ( ) Appendices . Background information . As a traditional naval grade , CPO was senior to a petty officer , and was the highest enlisted grade in organizations like Starfleet and the US Navy . In comparison to infantry ranking systems , this rank was approximately equivalent to the more senior sergeant grades . Personnel of this grade can be addressed simply as " chief " . In , Captain Kirk , saved by an enlisted man from , who intended to assassinate him , was told that " " Mr . Chekov was going to make me a chief , sir . " " In , a chief petty officer contacts the CDO Commander Rogerson , regarding a power drain in the energy systems of the aircraft carrier " Enterprise " . The CPO ' s voice is not heard on screen , but the commander responds to the question " " Yes , chief . We ' re tracking that too . " " Information pertaining to the " senior chief petty officer " and " master chief petty officer " ranks originated from Robert Fletcher ' s personal costuming notes ( p . 9 , seen ) and later confirmed in multiple lots sold in the It ' s A Wrap ! sale and auction . Props designated as " master chief petty officer , second class " were apparently designed and created , but did not appear on Fletcher ' s notes , were also among the costume props sold in It ' s A Wrap ! . Additionally , the revised shooting script for " Star Trek IV " was prefaced with several production notes , including one that stated : " " Please note that Master Chief Petty Officer Rand now first appears in Scene 25 and in all subsequent Starfleet Command scenes , " " replacing the previous script note reference to her being a lieutenant . A similar note appeared during the production of " The Motion Picture " , which originally listed her as an ensign , but was revised to chief ( no sleeve stripes ) , due to her position as the transporter chief .