Master Chief Petty Officer

A Warrant Officer is an officer in a military organization who is designated an officer by a warrant, as distinguished from a commissioned officer who is designated an officer by a commission, or non-commissioned officer (NCO) who is designated an officer by virtue of seniority.

Use in Starfleet

Master Chief Petty Officer is the most senior regular non-commissioned rank currently used by Starfleet. The Marine rank equivalent to Master Chief Petty Officer is Sergeant Major.

Master Chief Petty Officers generally only serve as department heads; or, more commonly, as the Chief of Boat. They have many years of service and a wealth of experience in their selected field. There is usually only one Master Chief Petty Officer assigned to a starship at any one time, although it is possible to have more then one Master Chief Petty Officer if the other one serves in a department head position. Master Chief Petty Officers are at the top of the Enlisted/NCO ladder and can therefore not be promoted further; although they can apply for a warrant or commission.