Senior chief petty officer (SCPO) was an enlisted naval rate, a type of military rank used by the service organizations of different cultures. As a traditional naval grade, SCPO was senior to a chief petty officer.
Personnel of this grade could be addressed simply as chief (or more properly, "senior chief"), and sometimes by their job title, such as "senior chief specialist." (DS9: "Shadowplay")
The rank of "senior chief petty officer" was never referenced in dialog, but is rather derived from rank insignia.
O'Brien was referred to usually as "chief" or "chief petty officer." He was referred to as chief petty officer in TNG Season 4 and again in DS9 Season 3 and beyond. Presumably the DS9 Season 2 reference in "Shadowplay" to "senior chief specialist", means the term "petty officer" can be used interchangeably with "specialist". In the US Navy "chief petty officer" can also be used interchangeably with "chief specialist". In Starfleet "SCPO" might be the person's rank, while "specialist" is their title.
See also: Starfleet ranks and Starfleet enlisted personnel.
| Enlisted personnel | Commissioned officers | Flag officers | ||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Fleet: | CRM | PO | CPO | MID CDT OC WO |
ENS | LT JG | LT | LT CMDR | CMDR | CAPT | FCAPT | CDORE | RADM | VADM | ADM | FADM | ||||
| Military: | PVT AMN |
CPL LCP |
SGT | SSGT | MSGT 1SGT |
2nd LT | 1st LT | CAPT | MAJ | LT COL | COL | BRIG | MAJ GEN | LT GEN | GEN | MARSHAL | ||||
| Services: | Andorian • Bajoran • Cardassian • Ferengi • Human (CSA • Third Reich • UE MACO • USA) • Jem'Hadar • Klingon • Romulan • United Earth/Federation Starfleet • Vulcan Mirror universe: Terran Empire Starfleet • Terran Empire MACO | |||||||||||||||||||
This chart shows only general equivalencies based on the ranks used by many governments on Earth, as well as the rest of the galaxy.