Captain (United States O-6)
In the United States Navy, United States Coast Guard, United States Public Health Service Commissioned Corps (USPHS), and National Oceanic and Atmospheric Administration Commissioned Officer Corps (NOAA Corps), captain is the senior-most commissioned officer rank below that of flag officer (i.e., admirals). The predecessors of the NOAA Corps, the United States Coast and Geodetic Survey Corps (1917-1965) and the Environmental Science Services Administration Corps (ESSA Corps) (1965-1970), also used the rank.
Reflecting its nautical heritage, the term "captain" also sometimes is used as a military title by more junior officers who are serving as the commanding officer (CO) of a commissioned vessel of the Navy, Coast Guard, or National Oceanic and Atmospheric Administration ship of patrol boat size or greater, while officers below O-6 commanding aviation squadrons (typically O-5 commanders) will usually use the less formal title of "skipper." (see rank vs. title)
USN, USCG, USPHS, and NOAA collar or shoulder insignia on select uniforms
The eagle, shoulder boards, and dress blue sleeve stripes of a U.S. Coast Guard captain
The eagle, shoulder boards, and sleeve stripes (dress blues + female dress whites) of a USPHS captain
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