A Starfleet Executive Officer, alco called First Officer and "XO", was second in command of a ship, station or facility or other unit as well as run the Command Department
On some vessels, reardless of size, the XO would head up another department in addition to Command. Spock served as Chief Science Officer in addtion to First Officer under James Kirk , as did Kiva aboard the USS Lionheart.
Normally Commanders and Lieutenant Commanders held the position, though depending on the size of a vessel Ensign Junior Grades could serve.
- Serve as Department Head for the Command Department as well as oversee the other department heads
- Make sure the CO's orders are implemented
- Adivse the CO, especailly when they are overstepping their authority
- Prepare duty rosters
- Oversee managing the ship's resources along with the OPSO and SUPPO
- Assume command in the CO's absence, death or incapacitation
- Hold briefings and meetings
- Oversee crew training
- If present, work with the Executive Assistant on civilian affairs
- Prepare crew for diplomatic duties
- Act as an officer of the court if none are available