The Senior Staff is comprised of the Commanding Officer, the Executive Officer, and the department heads of each area within the starship or installation. In most cases, the CO will confer with this staff on matters of importance (such as a First Contact situation, battle plan, or other emergency situations) before making his own decision. All other crew members of the starship or installation report to at least one of the Senior Staff. Senior staff positions are typically filled by officers at the Lieutenant rank or higher, but can be filled by an Ensign or Lieutenant, JG in rare cases.
Possible Members of a Senior Staff, showing the chain of command:[]
Note that unless otherwise noted, "Chief" positions are typically equal in terms of authority. The exceptions to this are as follows:
- In matters affecting the entire ship, seniority or a prior-appointed chain of command takes effect. For example, if both the CO and XO are incapacitated, the Second Officer (generally one of the Department Heads) will take command, becoming the CO for the duration.
- When a pre-determined chain of command has not been established, the most senior officer will take command. For example, a Lieutenant Commander would have seniority over a Lieutenant.
- If two officers are of the same rank and department, the officer serving the longest at that rank would be the more senior. For example, a Lieutenant Commander that has just been promoted to that rank would be inferior to one that has served for a year.
- In emergencies involving a specific situation, where the normal chain of command is not clear, the most appropriate officer will take command. For example, the CMO would be the most appropriate to command during a medical crisis, while the Chief of Security would be more appropriate during a tactical or security situation.
- When a pre-determined chain of command has not been established, the most senior officer will take command. For example, a Lieutenant Commander would have seniority over a Lieutenant.
- Despite their relative equality seniority, it is generally understood that Chiefs of a specific Department will have greater authority over that department. For example, if both the Security and Engineering Chiefs give conflicting orders to an Engineer regarding an Engineering procedure, the Engineer would be expected to follow the Chief Engineer's orders.
- The Chief Medical Officer and Counselor have complete authority in Medical matters, superseding even the Commanding Officer. However, the CMO is typically not in the normal chain of command unless they have completed Command Training.
- The Counselor may or may not be a separate position from the CMO. In many cases, the Counselor may be considered inferior to the CMO, especially if the CMO is of a higher rank.
- The Strategic Operations Officer operates outside the normal chain of command, bypassing the Executive Officer to report directly to the station or fleet's CO.
- The Chief of Security has the authority to arrest anyone if there is reasonable suspicion of a criminal or court-martial offense. This does include the CO, XO, and CMO, but typically requires significant proof or higher authorization (i.e. from Starfleet Command). Making an arrest of a superior officer also bears significant risk to the security officer's career if the arrest is proven to be unwarranted. This authority also extends to anyone operating within Starfleet's jurisdiction (i.e. arresting a known criminal inside Federation space).
- The Chief Medical Officer and Counselor have complete authority in Medical matters, superseding even the Commanding Officer. However, the CMO is typically not in the normal chain of command unless they have completed Command Training.
Additionally, the Chief of Operations and Strategic Operations Officer are typically only found on board a starbase or fleet flagship, with the latter usually only needed during a state of war. Diplomatic Officer are also fairly uncommon, often limited to larger starships or fleets operating in a diplomatic or exploratory role.