Petty Officer First Class
A Petty Officer First Class is a military rank the equivalent of which is used by the service organizations of many civilizations.
Use in Starfleet
Petty Officer First Class is a non-commissioned officer rank in Starfleet. The Marine rank equivalent to Chief Petty Officer is Staff Sergeant.
A First Class Petty Officer is a senior enlisted person, having generally served eight years in their occupational speciality to advance to this level. First Class Petty Officers may supervise a group of junior enlisted within their same speciality. This is a pivotal time in an NCO's career, the path before them is split two ways: PO1s may take a competitive, fleet-wide exam, and are judged by a board of current Chief Petty Officers to be promoted to Chief Petty Officer; or, in rarer cases, apply for a commission based on their fleet experience thus far, to be promoted to Ensign. Most PO1s remain as a PO1 for five years before traveling down one of these paths.